Alesis HR-16

Circuit Bending and Modifying the Alesis HR-16

UPDATE 2013 Sept
Added pitch mod info, bunch of new photos, etc.

UPDATE 2010 Nov. 26
- Upgrade your HR-16: sample and OS chips are for sale.
- HR-16 custom sample ROM software is available for free (non-commercial) download!
CEG v 1.4.2 (windows) Setup_CEG_V1.4.2.zip

Like most digital drum machines from the 90s, the HR-16 is great for circuit bending. However, it can be a bit unstable, even when unbent. Take a look at the service manual- it is a long list of repairs and upgrades. I wouldn’t recommend it as a first bending project. If you get into bending HR-16s, you will most likely end up having 3 or 4 HR-16s in various stages of disrepair, scavenged for parts for your one working HR-16.

Common repairs are: replacing the internal battery, SRAM chip, volume and data faders, LCD screen, and repairing the button conductivity. Eventually, I’ll post more detailed info about these repairs…

Sample and OS ROM Upgrades


The original grey HR-16 came with acoustic drum samples. Alesis later released the black HR-16:B which featured more “modern” electronic samples. The HR-16:B also came with an upgraded operating system, 2.0, that was more stable and had new features like SYSEX MIDI dump. Some musicians still preferred the original acoustic samples, so Alesis released a version of the 2.0 operating system for the original HR-16. The label confusingly reads: “Alesis HR-16:B & HR-16.” The startup screen does not display an OS version number, but as far as I can tell, it is more or less identical to the HR-16:B OS 2.0, except it is compatible with the original acoustic HR-16 sample ROMs.


An HR-16 or HR-16:B can be upgraded or “downgraded” by replacing the OS and sample ROMs. Alesis was kind enough to put the OS and sample chips in sockets for easy removal. If you have an EPROM burner, you can burn the rom files below onto EPROMS to upgrade or downgrade your HR. For OS chips, use a 27C256 EPROM. For sound chips, use two 27C040 EPROMs.

The SR-16 is based on the HR-16. You can almost think of it as HR-16 v3.00, but it is not compatible with the HR line at all. I’m including the SR-16 ROMs here in case anyone wants to compare them with the HR-16. Since both the SR and HRs use the same size sample EPROMs, you can try swapping chips between machines to get some weird sounds, if that’s your kinda thing. ;]

HR-16, HR-16:B, SR-16 OS and sound ROMs:
HR16_V2_0.BIN : HR-16 OS V2.00 “HR16:B & HR-16″ (most current)
HR16_V1_09.BIN : HR-16 OS V1.09 (outdated)
HR16_V1_07.BIN : HR-16 OS V1.07 (outdated)
HR16_U15.BIN : HR-16 sample ROM: IC U15
HR16_U16.BIN : HR-16 sample ROM: IC U16

HR16_B_V2_00.BIN : HR-16B OS V2.00
HR16_B_U15.BIN : HR-16B sample ROM: IC U15
HR16_B_U16.BIN : HR-16B sample ROM: IC U16

SR16_V1_04.BIN : SR-16 OS V1.04
SR16_U5.BIN : SR-16 sample ROM: IC U5
SR16_U6.BIN : SR-16 sample ROM: IC U6

Custom sound chips:

I was able to reverse-engineer the sample data, and I burned new sound chips with custom samples!

They are available for sale here:
HR-16 Custom Sample ROMs

And I’ve posted detailed DIY instructions here:
HR-16 DIY Sound ROM Tutorial

Adjustable Pitch Mod

It is possible to add global pitch control to the HR-16 by installing a high-speed clock circuit. One common circuit uses an LTC1799. They are sometimes available at circuitbenders.co.uk and at getlofi.com. Below is a photo of the basic circuit you need to build- you have to add a limiting resistor and a capacitor, as well as wires to connect to power, control potentiometer and clock output.

LTC-1799 clock circuit

You may think that you need to replace the crystal, X1, as with other pitch modifications, but that will adjust the clock speed for the whole machine, including tempo. A better method is to replace the clock signal that controls how fast the samples are read from the EPROMs. That signal can be found going into pin 37 of the ASIC chip, as seen in the photo below, courtesy of Squidfanny. You will need to cut the trace that goes to this pin and solder a new wire that will send our new clock signal to pin 37. You can choose to ignore the original clock and replace it with your adjustable clock, or if you want to be able to snap back to the stock pitch you can use a switch to toggle between the new signal and the original signal from the cut trace.


You may prefer to solder all your wires to the bottom of the board, as seen below. On the left, you can see the connections to the address and data lines of the sample chips for circuit bends, which are explained later… Towards the bottom, you can see a wire connecting directly to ASIC pin 37, and another going to the cut trace that originally connected to ASIC pin 37. Towards the right are two wires for power to the LTC1799. One connects to the ground found near the sample ROMs, the positive wire connects to the 5V regulator. The small orange wire was there originally, probably from when the machine was serviced last.


Circuit Bending the sound ROMs

UPDATE: Stay away from the “PCM54HP” chip! A couple people have said they did damage to their HR-16 when trying to circuit bend that chip. Gordonjcp says: “The PCM54HP is the DAC that turns all those numbers into sounds. It may well have fairly high voltages on it – not dangerous to you but well above the 5V that the logic chips expect!”

The HR-16 and HR-16B are great drum machines on their own, but there are tons of wonderful PCM-scrambling bends hiding inside. The sound ROMs are the two 32-pin chips. They are read-only versions of the 27C040 4-meg EPROM:


Connecting different combinations of pins on the sample ROMs yields flanges, distortions, gating, ring mods, etc. Some pins even output synth-like tones when you connect them to an audio amplifier. You’ll want to stick with only the address, output and GND pins. Avoid the VPP, VCC, /CE, and /OE pins.

<a href="http://burnkit2600.bandcamp.com/album/digital-drum-destruction-derby-demos-vol-ii-alesis-hr-16">HR-16: loafyness by Burnkit2600</a>


circuit bent HR-16B

The hard part is coming up with an interface that lets you use the bends effectively. This HR-16:B was a commisioned piece i did for Sam Spiegel (N.A.S.A., etc). He wanted something crazy that utilized as many combinations of bends as possible. I used 4 pairs of 6-position rotary switches.

circuit bent HR-16B

Each pair is wired together, for a total of 6X6=36 bends per pair.

Each pair can be turned on or off with the 4 toggle switches. It starts to look like some WWII-era German Enigma machine when you calculate the total possible configurations this thing can be in. According to my math, the total possible configurations is 1.78 MILLION! The LEDs indicate what bends are active, and plus they just look rad.

circuit bent HR-16B

There are countless options for interfaces! I’ve re-wired old TV remotes and video game joysticks so that each button, including up, down, left and right will turn on a different bend. The joystick is connected to the HR-16 via an RCA patch bay. I like this method also, because you can “play” the bends, instead of just putting the HR-16 into different modes.

Other Pages


    i’m interesting about bending my hr-16b.
    i saw your website and may be you can tell me more about this bending job.
    i’m a french electronic newbie but i read about circuit bending and they say thats it not so difficult to realise.I just don’t want to burn my hr16b and i’m looking for some precious advices about it.
    May be you can help me ! ? !
    I think i should know which pins of the two 32pins chips can be connected together without troubles.
    If its possible just let me know some tips and tricks about these 32pins

    Thank you
    Best regards

  • hi, jeremy-
    i’ve been working on an hr-16b for the past couple weeks.
    A few pin combinations will crash the machine, but do no permanent damage. Of course, once i crash the machine, i immediately pull the wire away. I’ve also been superstitiously avoiding the smaller pins at the corners of each chip. Be sure to connect the pins on the 2 sound chips ONLY.

    [EDIT] Yeah, i would stay away from pin1(program supply) 22(chip enable) 24(output enable) and 32(+5V)

    Good luck and happy bending!

  • justin you sunuvabeat you did it.
    youve turned your drummachine into a 8bit sample banger.
    excellent work. how many chips you burn up?

  • heh. i burned thru 4 chips. So now it’s time to get an eprom eraser. But in the meantime, i still have 2 fresh ones- Gonna see about piggybacking them ontop of the original chips, and wire the CE (chip enable) pins to switches so i can switch between the old and new sounds. I wonder how many chips i can stack this way….

  • you’re probly only limited by the case depth!
    you could piggyback an an ic holder to the outside of the instrument so you dont have to open it up every time you rip off a new set of aphex sounds.

  • Yeah, that’s similar to what Jesse wants to do. He wants to make a cartridge port, and then make up new carts.

    Haha. yeah, the aphex was just the samples i happened to be using when i got it right. I’m not sure what samples i’ll put on the first REAL roms. I’m thinking some roland 606, 808, amen breaks, maybe some blippy NES samples…. Maybe i’ll chop up some burnkit samples. =]

  • It *should* be pretty simple to figure out the data width of the samples.
    Assuming the DAC is 16 bits wide, how are the two EPROM data lines
    connected to the DAC? I assume it would be 8 bits from a low ROM and
    8 bits from a high ROM, but depending on how many pins are on the
    ROMs, I suppose it’s possible they are 16 bit wide ROMs instead of the
    more common 8-bit wide ROMs. Another way to tell is if the address
    lines on both ROMs are all common. The square chip is a gate array I
    assume for providing the clock signals to the ROMs. The CPU is the
    8031 chip in the 40 pin package.

  • Jesse Smith has the service manual on his site:

    The DAC is 16 bits.
    According to the manual:
    “The mask ROMs contain all of the sample information. The 18-bit
    addess buss allows for 2 megabytes per mask ROM. Address line A19 from
    the ASIC is actually used in conjunction with Q15 to switch the MAsk
    ROM /CE lines (pin 22) such that only one device is enabled at any
    given time.”
    And then it goes on to say that even tho the ASIC outputs 18bits, the
    DAC is still 16bit.

    So… the address lines on the 2 roms are common, yes? Each chip has
    half of the samples on it. They must get enabled and disabled real
    fast when samples from both chips play at the same time.
    They are 32-pin. I think this is the pinout:

  • Nice, though no schematics that I could see.
    It’s curious that they chose this addressing scheme. Maybe due to lack
    of pins on the gate array (ASIC). Theoretically two 512k x 8 eproms
    could be operating in parallel feeding the 16-bit DAC. Anyway, one
    would need to find the locations in the EPROMs for the sound start and
    end. You’ll need to load the EPROMs into an eprom programmer in
    split mode and reassemble the 16-bit words. Then you might be able
    to chart the sounds to find the start and end points (since it’s sound data,
    the magnitude should go up rather quickly and then “fade” out).

    One thing I noticed with Alesis is they may have scrambled the data lines.
    you look at the main LCD you can read the words displayed (obviously)
    but if you look at the 8031′s EPROM contents, the words cannot be
    found. So I wonder if the data lines to the LCD were scrambled or if
    the LCD data was encoded some way. It’s one thing I might look into
    some day. So if Alesis scrambled LCD data, the odds are good they
    would do the same to the sound data.

  • Well, i can find the start and end points of the sample data on the
    sound ROMs. I was able to replace all the sounds on one rom, so far.
    What i’m not sure of, is how the 8031 addresses the sounds, and
    handles the LCD data(drum names). Do you need a decompiler to view the
    code of the 8031? I think Jesse Smith mentioned something about a
    decomplier, but i’m not sure.

  • Thanks for posting this, I’m thinking I will buy one of these things armed with this information. Very cool.


  • you’re welcome.
    I should also mention, for anyone else looking for these things, that there are 2 very common problems with the HR-16. The buttons wear out, and by now the battery memory is dead. Buttons can be repaired easily with one of these kits. And you can get a new battery from mouser electronics. I dont have it in front of me now, but it’s a 3.6V lithium.

  • How did you wire those LEDS to the rotary switch? Did the switch come with them pre connected?

  • No. the rotary switch is a double-pole. So one pole selects the 6 bends, and the other pole is connected to the 6 LEDs. I just found a point on the board where there were a few volts, and ran that to the switch.

  • Nice, very suave design. If i understand correctly you just put one bend per “notch” on the roatery switch?

    How did you wire those middle toggles to disable the pairs?

    Thanks justin!

  • Also i was wondering if a patch panel set-up would be a good idea for this?

  • The way a 6position rotary switch works is it has one center point, and that gets connected to any one of the 6 outer positions. So if you only have one rotary switch, you are limited to only 6 bends, and they all share a common point. But if you take ANOTHER rotary and use THAT as the center point, that gives you 6 possible “common points” instead of just one. So you have one group of 6 points, and another group of 6 points, and you can connect any point from group A to any point in group B. So that gives you 36 possible bends. The toggle switch breaks the connection between the 2 rotaries.

    Yes, a patch bay would be a good set up for something like this too. My latest HR-16 uses a combination of rotaries, toggles, and a patch bay.

  • thanks alot … i just got my self a roland 626. i will implement some of these styles into it.

    thanks for the help.

  • awesome. you’ve seen our tr-626 section, rite? There’s discussion right now on the tr-707 yahoogroup about custom roms for the roland machines. Apparently, they are a lot trickier than the HR-16 in that regard, but still very bendable.

  • Yea that looks alot more involved to burn custom roms… i will probably stick to just rom bends.

    Great idea with the NES sounds for your HR 16 … be sure to post a clip of that!

  • Hello!fantastic your idea for burning hr16-rom simply and fantastic it’s crazy ! i have bent many hr16 and it’s my favorite bent gear, i want to burn rom and built hr16 with cardbridge ( i think to mastersystem cartbridge but one question it is necesary to change the two ship or you think just one ship is cool? for have half original sound and half personal sound ?

  • You can change one ship, if you like, or both. ;p
    Yes, a cartridge system would let you swap roms. However, i think the design i’ve settled on is an internal rom-switching board. I can fit 3 or even 4 sets of rom chips that way. I will wire all their /CE pins to a rotary switch (or 2), and i’ll be able to switch banks, maybe even while the machine is playing.

  • Hi Folks, I have a couple questions that I was hoping you guys could answer. I have a HR-16, it has a couple issues. In trying to fix it I found out about the bending potential. Thats good stuff, you guys do good work.
    If you are not too busy, or just feel like helping a brother out, let me ask you this.
    1) Do you know the details on the internal battery. I would say this thing needs replacing, because occasionaly it just looses its memory.
    2) Do you have further details on the nintendo joystick controller you mentioned on the site, is there a seperate site that you could refer me to?
    3) For bending. I got the general idea. I opened it up and looked at the two chips involved. All you are doing it soldering wires directly onto the actual legs of the chips themselves. correct? So for example, the if you connect pin 2 to pin 3 some strange noise might happen? On your site you mention the 4 sets of 2, six posistion double pole switches. Is this a prefered method or do you have other suggestions. Could you also help me understand how these switches are wired. I think this is the issue that I have the most need for clarification.

    4) on the site there was a note
    EDIT] Yeah, i would stay away from pin1(program supply) 22(chip enable) 24(output enable) and 32(+5V)
    Is there any further updates on anythign to avoid?

    I really appreciate your time, and also thanks for the excellent resource. If you have any links to point me to that would also be greatly appreciated.
    Have a nice day,

  • 1) The internal battery is the same as the Alesis MMT-8. You can refer to this MMT-8 FAQ for more info.

    2) The mods i did to the joystick can be done to ANYthing with buttons. You will most likely need to cut the traces on the circuit board inside the joystick- because they will probably share a common ground, which you might not want for your bend interface. Then, instead of using the original wire and plug, solder wires directly to the button contacts, and wire up some kind of connector to those wires. I used RCA plugs, one for each button, and use it with an RCA patchbay on the HR16.

    3) Yes, the bends simply connect one pin to another. And you can combine bends. If you wanted, you could simply cut a hole in the HR, exposing the chips, and attack then with a screwdriver, or bits of wire. Different people come up with different interfaces. I explain the rotary switches above.
    There is a modifed NES (which is brilliant, btw) done by Pixelform, and he uses the same idea, but explains it differently.

    4) No, i dont know of any other dangerous points. If you stick to the address and data pins of the two sound roms, you should be fine.

  • Hi

    How do you count the pins on the chip(s) ? clock-wise or counter- ?

    Oh yeah and would it make sense to take ALL the pins to the outside of the machine ? like a megapatchbay
    Or would I just be wasting time because everything does the same ?

    and .. both chips share the same traces per pin (read that somewhere) or.. ?

    thanks, K

  • If you do a search for 27C040, you can find the pinouts. It goes counter-clockwise.

    You don’t want to use ALL the pins- stay away from pin1(program supply) 22(chip enable) 24(output enable) and 32(+5V). Everything else is fair game.

    Yes, both chips share the same traces. (so chip1pin13 = chip2pin13) Technically, only one chip is active at any given moment. One or the other is activated thru the chip enable pin (22). You could only solder wires to one chip, if you want. What i did was solder to even pins on one chip, and odd pins on the other, so that i never had two adjacent pins soldered- that can get messy.

  • Hi, awesome resource. 2 questions. 1. how do you rate the different bend sounds of the hr16 and the hr16b? Is one better than the other? 2. Would it be easier to solder patch bays on the top instead of the rotary dialer? So how would you solder staggered between the 2 chips –the 1/8 ” plugs dont have to be grounded right? Just simply connecting one pin to another? I’m really interested in doing this to my 16b. Also, any suggestions about bending my old roland tr55? It sounds incredible nomral through a big muff and flanger -it’s beggin to be bent.

  • I want your opinion on the hr16 bend done here: http://www.circuitbenders.co.uk/drummod2.html#hr16

    Which method gives you more unique opportunities for creativity?

  • Kimo- that sounds like more than two questions to me! I like the HR-16B sounds better, unbent. So i guess i prefer the HR-16B bent sounds also. I’m in the process of making a rom-switcher board for my HR, so i’ll be able to have A, B, and whatever else i come up with for custom sounds.

    Is it easier to do a patchbay? Not necessarily, no. They seem to be pretty popular, tho. Wintermute over at robots in motion has an elegant solution- replace the volume slider with a pot and use the extra real estate for a 25pin jack. Then you are not limited to only one interface, you can make multiple break-out-boxes and swap them when you want.

    “Stagger solder” the chips- Yes. You can solder to even numbered pins on one of the voice chips, and odd numbered pins on the other, and it is the same as soldering to all pins of one chip (the 2 chips share connections between pins)

    No, your jacks don’t have to be grounded. Just connect their contacts to pins on the chips. You only need one pin per jack, unless you want to get fancy.

    TR55? Good question, i have a TR77 that i want to do stuff to. I know it’s possible to find trigger ins for each of the drums, and most likely pitch, decay and other parameters as well. Look at comments on my synsonics page, as well as Dave Wright’s Hammond Auto-Rhythm.

  • Nice job. I am really liking what you are doing with this… I am going to start experimenting with some bent gear of my own. Could you recomend a drum machine that would have some really good bends (similar in sound to yours), and that is a bit newer? I would like to have more: memory/user banks/more ins & outs/external triggers etc. I am not at the point where I can make those types of mods, so a newer drum machine would be better for me… I am just getting into this, so any help would be greatly appreciated. I’ve got you bookmarked, btw. Again, I really like your work. I’m looking forward to seeing what you do next.

  • Thanks.
    Well, any machine that uses PCM samples will give you similar results. Newer machines may have smaller surface-mount chips that are dificult to solder to, so keep that in mind. The HR-16′s younger sibling, the SR-16 is VERY similar. The 90′s Boss stuff is probably good, too.

  • Thanks for the info.

  • hi, i bought an hr-16 and later found out about the bending scene online. i seem to understand the idea behind it, but am a little concerned about the power source while testing the new bends out. all i can think of is to solder a 9V battery snap’s leads to the circuit board, but is this necessary? thanks

  • Do you think the Boss DR-202 would be a good choice?

  • Beardshop- This is a common concern amongst benders. Ideally, your wallwart AC adaptor should be outputting a safe amperage. But i’ve heard some people say there is still a chance of a failure that could yield dangerous voltage. So I can’t tell you there is no danger. But i can tell you that I have personally had no trouble circuit bending HR-16s while they are plugged in, and i think there is more of a danger of you damaging the HR-16 than yourself.

    [EDIT] I just saw this post on EM411

      A fuse generally does not protect you from mains shock, because it takes ‘a long time’ (even for fast blowing fuses) to melt. Long enough for you to receive a fatal shock anyway. A tripswitch however is designed to flip very quickly, protecting anyone who might be touching metal things, but I havn’t seen these for 9v DC systems…

      What you can do, is attach a led (and series resistor) between the output (9v DC) wires on your wall wart. When you are poking around bending, if you accidently short out the power supply, the led will dim or go out. This is your key to immediately stop bending that spot. Most (probably all) wall wart power supplies can tolerate a momentary short, it takes some moment of time for the temperature in the transformer to rise high enough to melt the wire coils, causing an internal short (possibly to mains, this is why it’s dangerous). With the led giving you a warning that a short has occured, you’ll be able to disconnect the short you just made, before the wallwart melts internally, risking mains shock.

      With all that said however, you should use batteries if you want to be really safe.” – dach

    Stephen- I can’t find any info online about the DR-202, like how the sounds are stored. If it’s PCM, i can almost guarantee it is bendable. Otherwise, you need to find out how to scramble the data lines from the sample data before it passes thru the DAC and gets converted to sound. ;]

  • Thank you so much for taking the time to reply. This website indicates it is PCM –


  • hi, i finally got my hr 16 bent and making crazy noises happen, and then all of a sudden the display turned into garbage and now it is frozen whenever i turn it on! it has crashed periodically but not with this few bends, and would always reset. have i ruined the machine, or is there some solution to this problem? perhaps i have wired it incorrectly? i would appreciate any help with this

  • the first thing you should try, is removing all the bend wires you added (you took notes, rite? or take a photo) Check to see if there are any extra blobs of solder or little pieces of wire shorting something out.

    However, your problem sounds like a bad SRAM chip, which is one of the more common problems with these things. The most common problem is the buttons lose their conductivity. The internal battery expires after 10 years (they have dates printed on them) And, the SRAM goes bad. Anyway, your problem sounds identical to what Wintermute wrote on robotsinmotion.com:

      …”But my HR-16 came with original PSU and everything worked fine except there was no sound and the display showd odd characters :)
      …The HR-16 holds all its Pattern content in a (nowdays) small SRAM that is bufferd by a lithium battery to retain the data. The size of the SRAM is as indicated from its name (SONY CXK58256P12-L) a 32k * 8bit CMOS static RAM with low power standby option. The 12 indicates the speed of the RAM in nS.
      This part is not easy to find anymore since its obsolete at most suppliers. But there was a second version of this IC called CXK58257 that is as indicated in the service manual a 100% replacement part.”

    I managed to find a handfull of similar chips on ebay. My HR-16 didn’t have the garbled text problem, but it wasn’t retaining the settings and patterns, which is another symptom of a bad SRAM. I replaced it, and now it remembers the patterns just fine. You can try to locate one of these chips on your own, or i could sell you one of mine. Email me and we can work something out.

  • Might try the factory reset? it is documented in the lid of the thing, i cant remember it off the top of my head, but its like hold down record and erase, power on.

    i crashed mine a lot and this fixed it.

  • so i was looking in the manual again and saw that an easy fix for this problem might be as simple as replacing C20. does anybody have any schematics of the hr-16, as it isn’t labelled on the circuit board?? thanks

  • This thing is amazing. Can you build me one???
    Let me know :)


  • Stephen have you figured out how to bend the dr202? I read somewhere that it is one of the few midi compatible toys that can be bent easily. Let me know if you have and take some pics of said areas that are bendable

    (although I got mine cheap I dont want to burn (fry?) my money away :-)

    Thx email to kimowasabe@hotmail.com or post here

  • Justin,

    Thank you very, very much for this tutorial.
    Some days ago I burnt my first custom Eprom and right now I’m installing the interface for the bends. I’m absolutely amazed how powerful the HR-16 can be when used with custom ROMs. This will be my setup’s MPC, although an MPC can’t be bent… well, I suppose, it can, but I don’t have one and I’m not keen on getting one either.

    Right now I’m considering to also expand the Pattern/Song/Memory by Piggybacking another SRAM on the existing one.

    How about swapping Samplesets? I ony have finished one so far, but another one will be ready pretty soon.

    cheers and a happy new year,

  • Simon- hey, that’s great that you were able to burn a custom rom. I’d love to hear samples. There has been a recent development in this area. Jan a.k.a Wintermute, from Cologne, has written a program that automates the process! I just posted an interview with him about it, check it out!

    Swapping sample sets is relatively simple. You can piggyback one chip on top of another. You just need to activate one or the other /CE pin (pin22). The inactive chip needs +5V sent to the /CE. I’m in the process of designing a ROM switching board so i can “piggyback” more than just 2 chips…

    Memory expansion sounds like a neat idea. I know it can be done with the casio SK series. I’d be more concerned with making the stock memory STABLE, before we EXPAND it. =] A fresh battery and new SRAM should help, but you never know. These old Alesis machines are notorious for randomly losing their memory. It would be a good idea to come up with an external memory backup. Hell, a cheap mp3 player would do the trick, using the tape backup. If you were crazy enough, you could install the mp3 player INSIDE the HR-16, as an extra data backup. (Having the thing blip out on you just before a gig is NOT fun!)

  • maybe getting a more recent Firmware revision would be a good idea as well (although ‘recent’ is is a pretty strange word for something around 20 Years old). I have 1.06 which is very early and could contain bugs that are removed in later versions. Also in the sevice manual on the stormscorner site there are some recommended Hardware enhancements which maybe would help a little with crashing issues…

  • I have the HR-16:B firmware, and recently replaced the SRAM. It seems pretty stable. OF course it only takes one data crash to mess it up, so i periodically do tape dumps.

  • i found a lot of 27C040-12 EPROM. will they work?

  • sorry, i posted this on the wrong forum. i am asking about the EPROM to use as the DIY rom action. will the 27C040-12 work? i dont know what difference the -12 makes, or what it means. thanks

  • hex- the “-12″ refers to access speed. Low numbers means fast speed. As far as the HR-16 is concerned, you can ignore the speed, since the original chips are older and a lot slower than the ones made more recently. So 27C040-12 should work just fine. Oh, and this IS the right place for discussion about the HR-16, including rom modding. Let us know how you make out. Here’s some more EPROM programming info.

    Also- i just made an interesting “discovery.” It is possible to damage the sound roms. I don’t know how i did it. I brought my HR-16 home from practice, where i had been using it without any problems. But when i turned it on, it sounded bent, even tho all the bend switches were off. I searched and searched for the problem, and it turned out to be the sound chips themselves. All the sounds were distorted and short. I tried erasing the chips, to re-burn them. But they won’t erase all the way. Even with an extra long dose of UV. All the bits are stuck on “BF” instead of “FF.”

    I can only think of 3 possible causes for this.
    1- cold weather. It sat for a while in a cold hallway. It was 17 degrees outside, but it must have been above freezing in the hallway, maybe in the 40s or 50s.
    2- bends. I had some new bends wired up that i used for the first time that nite. But everything was fine until the next day. And when i turned it on, all bend switches were off.
    3- defective chip(s). It would only take one defective chip to make all the sounds messed up. I dunno?

    If anyone can duplicate this problem, and provide me with accurate info that can be duplicated in my machine (i.e. “connect pin 32 to pin 22, turn power on”), then i will send you a set of HR-16 sound roms of your choice (A or B), for free. =] But i have a feeling it’s just a freak occurance.

  • hi, I was wonder if it was possible to hook a 9v battery to the power supply of the hr-16. I don’t see why it wouldn’t work but then again i know very little about electronics and don’t feel like frying my machine. cheers.

  • short answer: no. Long answer: maybe. The alesis power supplies say “output: 10V AC” If that’s correct, there are 10V of AC going to the alesis, instead of DC, like a battery puts out. This seems weird. I know that i’ve only been able to get the HR-16s to work with it’s own PSU. I haven’t had luck with others.

    If you want to run the HR16 on battery power, you will have to build a new power supply. I can’t help you with that, but here’s the Service Manual.

  • I recently broke my volume potentiometer on my HR16B I contacted Alesis and they sent me the wrong pot,looks like it is for the SR-16 ,idiots, is there anywhere that I can buy the original pot or maybe I can just use a round one? like the one you have on yours?


  • You’re talking about the plastic shaft part, right? Those break off easily. Mine broke, and i just left it that way. =] I just leave it at full volume. I run everything thru a mixer. It should be easy to replace with a round pot. I’m not sure how it’s wired up (is it stereo or mono?), i’m sure you can find out by trial and error or by looking at the service manual.

  • Maybe a little OT, but here’s an option:
    I replaced the stereo volume slider on my QY10 with 2 separate mono pots. By panning the sounds in the QY to either hard left or right, you basically have 2 separately mixable outputs for more control. HR must have a stereo slider too.

  • Around 15 years ago my mate Malc’s HR16 PSU died literally an hour before a gig. I made him a new power supply out of an old ZX81 power supply with the rectifier and capacitor removed – ie. just hooked the power lead up to the secondary of the transformer. If you can find a 9v DC PSU that puts out about 1A that will be fine for your HR16.

    Warning – there is mains voltage inside. Applying 240V to your drum machine where it expects 9V will give you one loud, short sound and a bit of a light show.

  • Just to clarify- Gordon’s talking about high voltage being inside a power adaptor, not the HR-16 itself. I wouldn’t recommend power supply hacking to anyone, whether you have 240V or 120V (of course, it’s the amps that will kill you). That said, there ARE voltages inside the HR-16 that could damage the machine.

  • Well, I missed out on the TR626s that were on eBay but I just picked up an HR16 from a shop for 30 quid. Am I going to modify it? Erm, it’s a distinct possibility…

  • Haha, you know you can’t resist! Just be careful, HR16s can be old and cranky. I’ll be updating this page with some basic maintenance info soon… If you try the ROM replacement, i’ll be curious to hear your take on it.

  • Well at first glance at the ROMs, the sounds seem pretty straightforward. As has been mentioned elsewhere, there is that little “tick” to zero every so often. What I think that does is tell the ASIC to shift the output right by one bit. The “16 bit” claim is a bit fake – there’s only 8 bits worth of data but at the loud end of the sound those 8 bits represent bigger numbers than at the quiet end. For a comparison of a similar idea, look at the cymbal generators in the TR909, where the sample is flat along its level (like the 626 sample) but goes through a VCA which is controlled by the upper address bits of the sample position!

    The messages in the ROM do appear to be encrypted, but I haven’t found a good 8051 disassembler/emulator yet. I haven’t looked very hard though. I thought it might just be a data line swap, but some of the assembly language makes sense as-is. There is very nearly 32k of assembly code to go through…

    There *is* a disassembly out there but it doesn’t make a lot of sense – the first instruction is a jump, but it jumps right to the middle of another instruction. I suspect that it will need to be disassembled piece by piece so that we can keep track of odd things like this.

  • Yeah, i wouldn’t know what to do with assembly code….

      look at the cymbal generators in the TR909, where the sample is flat along its level (like the 626 sample) but goes through a VCA which is controlled by the upper address bits of the sample position!

    Do you think there’s any of that going on in the HR-16? I suspect the open/closed/mid hihats are the same sample put thru different envelopes, but i’m not sure. Ive had trouble replacing those samples. And some samples seem to have a bit of non-sample data at the very end, after the sound has faded out, but i’m not sure about that either.

  • Regarding the ‘Christmas Tree” waveforms, it looks like they were careful to avoid letting the waveform hit the “0″ value. That way, they can use a zero to control the way the data is sent to the DAC.

    Since each bit of digital audio is equal to 6db, it looks like the samples are first sent to bits 9 through 16 of the DAC, then each “zero” bumps the data down one bit. In other words, it would go like this:

    Bits 16 – 9
    Bits 15 – 8
    Bits 14 – 7
    Bits 13 – 6
    yada yada…
    Bits 8 – 1

    Does that make sense?

    This (I assume) is how the HR-16 is able to play 16-bit samples using 8-bit data.

    The trick, of course, is to convert your replacement sounds. You could do it in Sound Forge, but it might be a little time consuming.

  • oops, just noticed Gordonjcp’s reply…

  • dave_b: yes, exactly – it’s broadly similar to the mu-law algorithm, except in mu-law the upper bits set an exponent and the lower bits are the mantissa.

    It would *probably* be fairly easy to work out a little proggy to apply the compression for you – something like, find out the average level (not value) of the past few samples, and when it passes the half volume point tick to zero and double the output.

  • I wish i could be of more help in this area, but you guys are speaking greek to me- I have a lot to learn!

    A program to apply the exponential compression would certainly be cool, as it would increase the signal-to-noise ratio of custom sounds…..

    I just thought of something… Assuming we’re right about this, would it be possible to “trick” the DAC into adjusting the volume without changing the data in the sample roms? This would essentially allow you to shorten the decay of the drums. Would that be as simple as bypassing one of the address pins and replacing it with a high or low logic pulse (to “simulate” the zero spikes)? That could be a useful mod, if it is possible.

  • Try it! Wherever you insert a zero, it will ratchet down the sample bit depth and you get half the output.

  • Here’s a quick scribble on how I think the encoding and decoding could be done. Email me at gordon@gjcp.net if you have any comments, or leave them here.


  • The good news is that 16-bit audio files are pretty straightforward if that’s your thing. I was able to dissect one the other day (I used Perl, since that’s what I know). From there it wouldn’t be hard to convert them to an 8-bit Christmas tree file. If anyone wants to give it a go, I’d be glad to talk about the theory. It wouldn’t be that hard for someone who can code. I just don’t have the time.

    Justin, don’t sweat it. You’ve done plenty! :-) Now if we could only figure out where the names and file lengths are stored. I looked at the hex code the other day (yeah, I know) for a couple of hours before my eyes started doing wheelies.

  • The names and sample lengths are stored in the OS ROM. Now that *is* encrypted in some way, and I haven’t got much info on the hardware. I know it’s an 803x/805x-based CPU (think it’s actually an 8032). It might be possible to pick through it and work out how the screen is addressed. It might be possible to slow down the clock and follow it through with a logic analyser, but I don’t want to kill another drum machine ;-)

  • After looking at the firmware and loading the data into Excel, I’m guessing, the names are stored about 6600 bytes into the firmware. I still can’t figure out how it’s encoded, and I’ve screwed with it for a while now. FWIW, the data in that area, up to about byte 9200, is generally in the alphanumeric range, unlike the rest of the firmware.

    I doubt that helps but I thought I’d share it.

  • gordon’s previous comment (#66) was being held in moderation (sorry, spamfilter), it’s there now.

    dave_b- what firmware version are you looking at?

  • Justin: Don’t worry about it, it got there eventually ;-)
    dave_b: I reckon one of the first things it does is write the “boot” message to the screen on startup. If I could find an 8032 emulator/debugger it would probably not be too hard to work out what’s going on. It’s probably some fairly simple code – as far as I can tell the display is just expecting normal ASCII.

  • Gordon: I have an emulator made by FST called Simulator2003, it can be found at http://www.fstsoftware.com/. It will emulate the 8032. I havent had any luck figureing things out, but if you can give me any suggestions I would be glad to look into it. I have had hopes to change the sample names shortly after wanting to change the samples(almost 2 plus years now).

  • Well… after reviewing the 80C32 datasheet (http://www.keil.com/dd/chip/3422.htm), the 80C32 does indeed have the option of encryption as Gordon mentioned last month (sorry if I’m just catching up here).

    I used Excel to go through the firmware again (it’s the v1.09 file, Justin), trying to see if there was a simple ‘offset’ on the ASCII values. That didn’t go anywhere. Looking at how the first instruction jumps into “nothing” it appears encryption is probably the reason.

    I look forward to being corrected. :-)

  • To clarify, this is from the Phillips version of the datasheet:

    “If the encryption table has been programmed, the data presented at port 0 will be the exclusive NOR of the program byte with one of the encryption bytes. The user will have to know the encryption table contents in order to correctly decode the verification data. The encryption table itself cannot be read out.”


  • Let’s not forget what the HR-16 can do without modification (OK, I’m cheating slightly with an HR-16 with HR-16B ROMs…)

    http://www.gjcp.net/~gordonjcp/clattery.mp3 – an HR-16B, a fuzzbox, a tape echo and a swept filter.

  • dave_b: Are you sure it jumps into “nothing”? The disassembly I saw looks like it was produced by firing the ROM dump through a disassembler, which will generally not produce the correct results – if there’s a block of text or data that isn’t “proper machine code” the disassembler will try and treat it as code *anyway* and get itself out of sync. You’d need to follow each jump and disassemble it a routine at a time.

    The fact that the first three bytes are recognisably a jump suggests that at least *some* of the ROM is unencrypted – what are the chances of it encrypting to itself? None, unless you’ve got really crap encryption!

    Another technique we might use would be to search through the ROMs to find identical strings, and employ differential cryptanalysis to work out what’s going on. If we can identify a phrase (say “HR-16″) then we can probably work it out.

  • Just to reply to myself (rather rude, I always feel, but heigh-ho, here we go), on further investigation I’m not entirely convinced the encryption ROM is applicable to the 80C32. The 80C32 is described as ROMless, and the encryption feature is designed to prevent the ROM from being reliably read out after the chip is programmed. Since we have an external EPROM there’s probably not a lot of point in preventing it being read (since we can’t anyway – a simple dump of the ROM would be all you need, you don’t need to understand it).

    I’m fairly sure that any encryption of messages in the ROM are done in software.

  • I know the 8032 is of the same microprocessor family as the 8031, but the HR-16 has an 8031. Does all the above converstaion apply to both microprocessors?

  • Whats the best way to replace the internal battery on one of these things?

    While I’m at it: has anyone been successful at replacing the pads altogether? Mine has the stupid hard plastic ones, not the rubbery ones that everyone seems to hate. Of course any info regarding the pads would be most appreciated.

    My hr16 seems extra grumpy.

  • Whats the best way to replace the internal battery on one of these things?

    “Carefully.” You’ll probably want to do a sysex dump to save all your patches, but once you’ve got that out of the way it’s easy enough. There’s a page elsewhere on this site that details how you can replace internal batteries. I don’t know if you need to do any kind of factory reset, or if the CPU will take care of that for you.

    My HR16 has rubbery buttons for the functions, but hard plastic pads for the drums. Pretty much like any other HR16 I’ve ever seen…

    When you say it seems grumpy, what is it doing, or not doing?

  • BlueRabbit- If you want to save the pattern and song data in the HR16, then yes, you should to a tape dump first, like Gordon suggests. If you don’t care about the patterns, that’s not needed. The battery is a 3.6V lithium. There’s more info on the MMT-8 FAQ. The buttons lose their conductivity over time. Search online for “tv remote button repair kits.” It’s a conductive goop that you apply like paint to the rubber button contacts. Soon, i’ll be updating this page to include maintenance info like this.

  • You can apparently dump the patches using sysex, but I haven’t tried it yet. I used the silver-loaded paint you get for repairing car windscreens to repair the rubber buttons on my mate’s Sequential Sixtrak, but we found that the MMT-8 and HR-16 buttons came up lovely with a good clean.

  • You have to be careful when cleaning the pads because it’s possible to rub the conductive layer right off. Don’t use any abrasives.

  • Thanks for all the tips, everyone!
    Tonight ill be opening this bad boy up again to really have a closer look at the pad contacts (or whatever the term is), to see what their status is. Record and play seem to be the worst offenders at this point.

    (btw, grumpy = just not very responsive. Not the best choice of words, lets try “recalcitrant”)

  • Gordonjcp Says: “dave_b: Are you sure it jumps into “nothing”? The disassembly I saw looks like it was produced by firing the ROM dump through a disassembler, which will generally not produce the correct results”

    Admittedly, that’s all I was looking at (the disassembled file) since I couldn’t find a way to disassemble it myself.
    Sorry to drop off for so long, I’ve been working on a DrumKat that’s perfectly functional. :-)

  • Hi Justin, I was inspired by your use of led’s in your HR-16b above, and incorporated some into my patch bay switch system. they look really good!

    Bod's HR16

    i love bending these machines, i’ve done a few now and i keep finding loads of new sounds!



  • hi justin,

    first : thanks!!! this is exactly what ive been looking for. im using the hr in a project currently (mutating it with as s700) and combining into one box… and would like to add the rotary switch mod to the internal hr sounds. im having a hard time picturing how the switch leads go to the pin leads… can you help? sorry if this is remedial. thaks again!!!!
    shawn rudiman

  • also about the pads.. ive used hard lead pencil shavings (mostly graphite) to recoat the pads with in a pinch.. it lasts usually about a year or so.. shave the lead with a pazor blade then use a qtip to recoat the circular pad contact.. (also works for the function switches as well and the mmt control switches!


  • s. rudiman- wow. I’ve heard: foil and glue, conductive paint, a bunch of microswitches, cleaning, and now pencil shavings! this topic deserves a F.A.Q…

    The rotary switches each connect one middle point to one of six outer points. Actually, i’m using double-pole 6-position switches. One pole is for bends, the other for the LEDs. I have 2 of the rotary switches hooked together by their center points. So now i have 6 bend points that connect to 6 other bend points.

  • justin,

    thanks! ive actually gotten several steps into the process now and am really deep into the hack..the combo of the hr/s700 along with the hr hack i think will be a really cool lo-fi machine. chunky and blippy all at the same time. i have a question though.. is the volume slider on the hr- log or exponetial? also is the data slider the same?? id like to replace them with pots rather than sliders for eas of machining the face plate..?

    (ill put pics up soon.)

  • good question. I’ll have to find out- I’ll be doing a similar re-casing soon, myself. Keep us posted on your project, i’d love to see pics! How are you doing the case?

  • the case will be using the chasis (minus the front intereior housing of the s700 (its a good size and gives room). ive jumper all the old alesis rubber /contacts out to individual old computer keys (fantastic resource for free!!!) soldered them on to bread boards and will have truncs going back to the alesis boards (housed inside and mounted) to use the boards and such but not use the switches also it allows the aesthetics of the user panel to be real mc-4/linn lm-1 ish (LOVEM!)all controls for both and pads will be on that roughly 19.5x 10 faceplate. ive designed it so the 2 16 chrtr displays will be jumped to a thin angled panel (like an mpc 60II) in the middle. then above will be a patchbay for the hr hacks…

  • they will be connected into a “buchla” type cabinet. (slight angle , steeper angle then up and down). i may also add an et/drumpad input to the hr/ it seems the pads and the “velocity” is a brute force enginerring job. the pads can be hacked to accept external triggers in! there a 4 peizio’s on the back of board behind the pads.. just centered between groups of four zones. seems easy enough to tap the circuts of them for the triggers and then tap the piezo crt for the velocity (if needed even) thanks to the hrs (1-8 velocity scaling) so maybe have 8 pad inputs and switches for the top row.. makes it into a cool unit. also enables the hr’s to be made into 16 pad trigger converters!!!!!for almost nothin!

  • then the face plate and mid and patch panel are connected thorouly and then hinged on the back of the old 700 chasis (like an mpc60/dmx/linndrum)for easy matinence hacs/etc. add cherry/mahogany/sepeli sides… wah la… old school. drum computer! ill try and get some pics this weekend.
    let me know if you find out what the style of volume and tata sliders are (log or exp?)


  • By the way,
    HR-16B works with 9V, 1000mA AC/AC PSU. It did not work with DC PSU’s, although the lights lit up (and luckily nothing else).

    I had bad luck trying to find those on some piece of shit Clas Ohlson, I had to cut up the one I got from there to get a proper connector type.

    Hope this helps.

  • Hello!
    Just bought one of these on ebay, and when I turn it on, the screen lights up blank and the ‘PATT’ ‘TUNE’ and ‘SONG’ LEDs blink. That’s all that happens- no buttons respond.

    In you lot’s vast collective experience, what do you reckon might be wrong with it? I’m using a 1000mA 9v AC power supply, if that helps. I know that the P3 power supply is 830mA, but everyone I’ve consulted has said that that shouldn’t matter.

    Any ideas gratefully received!


  • Michael-
    Well, if you just got it on ebay, there’s no way of knowing how much it’s previous owner abused it. That does sound like the right power supply, as long as you’re sure it’s outputting AC, not DC. If you gave it DC, the lights would not light up…

    Those symptoms sound like the 3 flat grey cables inside that connect the button board and LCD screen to the main board might be mixed up. Maybe it’s previous owner opened it up and did not put it back together correctly. There are 3 cables- 3 connectors on the main board, 3 connectors on the button board, 2 possible polarities for each end. That gives you…. um….. 18 possibilites? Good luck!

  • Any of you find any ways to bend the sequencing functions of this guy?
    I’d like to be able to get in and screw with the patterns to make them randomize or trigger different spots in the pattern to add variation to beats.

  • That’s an interesting idea. I’ve only explored the sound chips. Any time I’ve strayed into other areas, i get weird crashes, and I’m too freaked out to look any further. A few people have commented here that they’ve perma-bent their HR-16s, so it’s wise to be cautious.

    Another idea i’ve been thinking of is to find a way to randomize midi data. This could probably be done easily with software. I’ve had good results triggering an SR-16 with midi arpeggios. That’s something i want to look into further.

    But if you want to dive into the HR-16, try messing with the SRAM chip, i think that’s where pattern data gets stored. Do so at your own risk, blah blah blah- I’ve never messed with that, and it may cause the moon to explode, etc. etc.

  • NB: Stay AWAY from the chip to the right of the CPU marked: PCM54HP, i just blew my ROMS with a bend point on that chip.

    Now. Anyone have a dump of the roms so I can burn new chips?

    totally not what i wanted to do tonight.

  • I have the HR16 and HR16B ROMs somewhere, I’ll need to look them out. The PCM54HP is the DAC that turns all those numbers into sounds. It may well have fairly high voltages on it – not dangerous to you but well above the 5V that the logic chips expect!

    In fact, here’s the site I got the ROM images from:

  • hey! and first of all thanks for tips , my first bent is almost ready. i soldered all the wires to my hr16 and all the wires/bends works fine, but now i got this strange little noise, even if no bends wires are connected. its sounds like some bending noise; random glitch/low bitrate noises on low volume… what do you think could be reason for this?? could it be bad solder points or something like that?? im a rookie at soldering..

  • It is most likely a bad solder point somewhere- too much solder on one pin, touching another pin. Or an extra bit of solder or wire that fell onto the board. It could also be interference between adjacent wires if you’re using ribbon cable. Have you wired the bends to switches yet? Another thing that happens sometimes is a switch will go bad and be closed all the time- if you heat it up too much during soldering, or just because it’s a cheap switch. Good luck, hope you don’t join the Perma-Bent Club!

  • Hi Chaps,I have a hr16 and want to save all the stuff i have already programed . Do i store it on a computer and if so, how do i do it. I am not very good with this kind of thing but if its simple enough i can follow intruction.

  • thanks for response, justin. i fixed some solder points and now this backround noise is not so bad, if have to put my mixer pretty loud to hear it. now it sounds more like interference type of noise .. i haven´t soldered switches yet, all the wires are in this connector now. two questions: normally is there any noise in HR? and how did you connectd your wires to the chip socket? picture seems strange .. i soldered wires to the backside of pcb like in vidiodsquad pics.
    thanks for advance

  • and one other question , could it be my powersupply ?? its not original alesis…

  • ok now its perma bent… what i can do now, new chips or what?? i dont really know what the fuck happened ,im sooo angry .. hours of soldering and shit , and this is the thannks i get. GODDAMN!!!
    thanks anyways
    pz out

  • shit, dude. sorry to hear that! I’ve killed no less than 3 HRs myself over the years. I think we need to start a Dead Gear Gallery. The HR’s that died on me had their ASIC chip go, i think (the square one)- which of course is one of the only non-replacable chips in the thing! At least i haven’t been able to find any anywhere… Well, keep checking ebay- every now and then an HR goes for like $50. You might be able to find a broken one (hopefully the owner wasnt trying to circut bend it, tho), and use it for parts.

  • im going to make it work somehow, bends still works , but one of them is constantly on :(… i think i just pimp the box and put some switches there. then when i get new one, i just have to solder some wires.. btw , what kind of wire do you use?? how thick? i didnt have too much space under the pcb, and i think that was on of the reasons for noise i talked about ..
    anyway,i think i keep on bendin :D
    nice site you got !!!
    my music : http://www.myspace.com/levonzoltar

  • Yeah, at least it still makes noise, rite?
    I used ribbon cable and soldered to the bottom of the board. It’s pretty thin and doesn’t get in the way much. I’d recommend rainbow ribbon cable – it’s easier to see what wires go where.

  • yea, otherwise it works like “normal” bent HR. i think i have to get that ribbon cable, insides of my HR are little bit messy…

  • I found my old HR-16 when moving last week, and at first glance it seemed to still be working, but no sound is coming out of it. The buttons aren’t what they used to be, but still functional. I can start patterns, but I don’t know if they contain anything, since nothing is heard when they’re running. And pushing any of the plastic trigger pads does nothing. Battery is probably too old and dead (C1/12/87), but I guess that only affects pattern memory?
    Any ideas?

  • Hi, Covox! The buttons and battery are usually the first things to go. If the battery is dead, there will be no pattern data, so nothing will play back. But you should be able to tap the drums and get sound. Unless the buttons are dead. By default, the HR-16 “pad dynamics” is set to “loud response” which means tapping the drums lightly won’t produce any sound. Go into the menu and turn that to the loudest fixed volume, 9, and then try tapping the drums. If you have a midi controller, you could try plugging that in and see if you can trigger the drums that way. You can change all the channel and note response in the midi menu. Actually, now that i think of it, that’s another way you can test if the buttons are working. Go into the voice menu- the click sound will be listed by default. Press the drum buttons and see if the drum listed changes. It’s also possible that the volume fader is bad, does it sound scratchy when you adjust it?

  • Hey Justin, thanks for the quick reply! I tested the battery and it appeared to have some juice left. Also, the buttons were a bit unresponsive but I could activate them and change their assigned sounds. The volume slider was crusty, but cleaning it with the right solvent didn’t do any good. However, I found the service manual and did a diagnostic on the machine, and it seems the 8031 is busted. The self-diagnostic encounters a “MIDI I/O ERROR” and stops. Do you think it would be enough to just replace it? My local supplier has the P80C31SBPN variant in stock.

  • Did you do the self-test like the manual describes? You have to connect a midi cable between the midi in and out, and a 1/8″ cable between tape in, out.

    If the volume slider is dead, you can bypass it by routing drums to the 2nd output. Try that first.

    In the troubleshooting section, under “no sound at all,” the 8031 is not listed. It lists the ASIC, DAC, 4052, and op-amps (U20, U21). I think all those parts should be replacable, except for the ASIC (but if you find a source for that, let me know!)

  • Oh, totally missed connecting the cables. It passed the tests. Tried routing all sounds to secondary outputs, but still nothing.
    The ASIC and DAC seem to be a difficult find, but I’ll go ahead and replace the 4052 and op-amps at least. I’ll let you know if it changes anything. Thanks for all your help!

  • Ok, today’s lesson: Check your power supply TWICE. Apparently I have two visually identical wallwarts; one that churns out 9V/1A DC, and one AC. I had been using the DC one all along, believing it was AC. Feeling of stupidity outweighed by joy in functioning HR16 though. And I’m glad I didn’t get around to desoldering stuff.

  • Haha!
    Wait a minute…. You were using the DC PSU, and the HR-16 was powering on? It just wasn’t outputting sound? WEIRD!! When i’ve plugged DC supplies into the HR, it just didn’t power on.

    Yes, a good lesson, that I never seem to learn either- ALWAYS CHECK THE SIMPLE THINGS FIRST! Just last week, i did something very similar- I built a firestarter MC2 that “sorta” worked. Got MIDI, but wouldn’t output to the game boy. Couldn’t figure it out- Then i realized i had the power hooked up wrong! I fried 3 chips before i realized what i did!

  • yeah I’ve had the same reaction from it before with DC adapters, but for some reason this quality-one (stabilized Hama) is giving the HR16 _almost_ what it needs. Weeeiird.
    I read about your PIC problems on the mailing list. Super annoying when it happens, but glad it worked out in the end.
    Anyhoo, I’m glad I found my HR16 and your page, it sounds awesome already. I’m definitely going to be using this one.

  • Ok, I finished my HR16! http://fapfap.se/~thomas/hr16.jpg

    I found a cheap stash of 3.5 mm jacks, so I went for patch bay-style. Because the originale flip panel was too thick for my jacks I had to make a new one, and I figured I could just repaint the whole thing while I was at it. Btw, panel is made from plexiglass, paper fixed with spray glue and then covered with the kind of transparent adhesive plastic you put on maps etc.

  • Wow, that looks amazing! Very professional. I like how you kept the branding, but i’m surprised you didn’t put a Covox logo on there somewhere. =]

    So how did you attach the plexiglass panel to the HR? Glue? You must have used a drill press for the jack holes? Or at least a center punch and a hand drill. They’re very uniform.

    I’ll have to look into the adhesive plastic you mention, what’s it called?

  • Yeah, I kind of realised I should have put something like that on there somewhere :) Perhaps for the SK-8 waiting to get bent to hell.

    The plexi panel is glued. I used a powerdrill, which unfortunately wasn’t that exact, although close enough. A drill press would be a dream, but I guess a hand drill will have to do. I’ll get one and try on my next panels (a WSG and a Voice of Saturn). Or I could try and find some CNC geek close by… :)

    I don’t really know what the english name for it is, but I can snap a pic of my roll to give you an idea. It’s not entirely discrete because it was made to be durable enough to protect maps from wear and moisture, although it has a nice smooth texture. Plus it would probably survive even the most harsh liveset.
    I’ve ordered some nifty films from Letraset that I believe could be of good use for making panels. Check out their Safmat film.

  • By the way, how do you guys paint plastics? What kind of paint? Then, the HR-16 doesn’t have that issue, but what about labeling on other machines?

  • hey, does anyone here have a map of what the induvidual pins on the EPROM do? im gonna start work soon, but id feel alot safer if i knew what i was actually conecting to what.


  • Jesse “stormscorner” started a map here. When he says “IC1″ and “IC2,” he’s referring to the 2 sound roms, of course, which are labeled U15 and U16 on the board. But since the 2 roms are connected together, it doesn’t matter which one you try to bend, they should both do the same things.

  • Hello. I am new to this forum. I have a hr-16b that won’t power on
    with the mmt-8 sequencer power adapter. Is the power adapter
    different for the mmt-8 than for the hr-16b? If it is the same, does
    anyone know how I can fix this unit? It will not power on with the
    mmt-8 power adapter but the mmt-8 will power on with the same


  • Jeremy-
    Yes, the MMT-8 power supply should also work with the HR-16s. It should output 9V AC.

    Was this HR-16 ever working since you’ve had it? Are there any signs of life? Any lights that come on?

    Have you looked in the troubleshooting section of the service manual?

  • Hey team-

    I love what you’re doing with the HR-16, and I thought I’d pick one up. The unit works, needs to be cleaned up a bit, but the output level is really low. Does anyone know how I might go about fixing it? I don’t think it’s a faulty volume slider. Other ideas?


  • Check the “pad dynamics” setting, under the MIDI/util menu. Set it to the highest fixed volume. By default, it’s set to “loud response,” which means you have to hit the pads hard to get a loud sound.

    You can also try assigning drums to the 2nd output, which bypasses the volume fader, to see if the fader is faulty.

  • HI!

    Check my Casio Rz1 mod.


  • Neither set of outputs has any substantial volume. Any other ideas?

  • Hi
    i’ve been checking your site for the last year or so and it’s the best of its kind that i’ve seen, i’ve got 2 hr16s that are both giving me probs (psu). 1 i just bought the other i’ve had a while and have seen it work (with psu that i got with it but have now lost)It was interesting to read the probs other people were having with powering up,
    I thought it was sumthing to do with power, cause both were powering up (pattern and/or song light, also lcd lights up but no text on one the other has pixelated black block where there should be writing, kinda tricky to lay hands on british psu seen a few american ones, any ideas for sourcing psus for the hr16s?
    many thanks for all your help and inspiration!!

  • Hey Great job you’ve done there! I currently work on one of these and try to use LEDs aswell……..but I cant find the right points to get them supplied. Have already hooked ‘em up to an external power supply. everything is fine but all points I’ve tried on the board caused either a crash or made the machine behave naughty. Had to reset it for 4 times jet and dont wanna crash it permanently. Got any hints? Cheers

  • clone2-
    You might try asking alesis. I know some of their more current power supplies output 9VAC, so they might have one for you. Otherwise, you might want to try other EFX pedal places. You need something that outputs 9VAC. The symptoms you mention may be because of a bad power supply, or may be because someone opened it up and connected the internal grey ribbon cables wrong.

    Not quite sure what you’re trying to do. But i should clarify- the LEDs in the HR16B on this page are in NO WAY connected to the bends. They are seperate. The rotary switches i used are double pole, so that means i can make 2 DIFFERENT, ISOLATED connections at each of the 6 positions. One pole makes a connection between 2 pins on the sound roms, and the other provides power to one of the leds.

    However, you may also experiment with using LEDs between bend points. WITHOUT EXTERNAL POWER. Data is sent between chips in the form of on/off voltages, so it will cause the LEDs to flicker with the flow of data.

    Connecting points between random places in the machine can damage it! However, it is generally safe to do this with the address and data pins on the sound rom.

  • Unfortunately, both stormscorner and the CEG program websites are down- Which makes the ROM burning tutorial very frustrating!

    Does anyone have a copy of those programs, or is anyone in contact with the authors?

    Thanks kids, keep up the good work burnkittens!

  • I bought an HR-16 last month, and I found this page when searching for instructions on bending it. I’ve checked out your other gear and am now listening to your new album, and it’s _awesome_. I may just have to order the CD, once I get my paycheck. You haven’t been planning to visit Finland, by any chance? ;)

  • can anyone tell me the specs on the rotary switches(which kind to get)

    and how are the led’s hooked up

    email me at synthetic_solace8@yahoo.com

  • Hello all. First off, great website! It has helped me no end with various stuff, especially my hr-16′s! Just a short one about a find I thought you may be interested in. I replaced the crystal in my HR and replaced it with an oscillator (from getflofi, but you could build one yourself) and now I have several octaves worth of pitch shift available.

  • Oooh, neat idea! I’ll have to try that! =] I love the way PCM-circuit bent stuff sounds when it’s really LOOOOOOOOOWWW…

  • yeah, it does sound cool. especially with custom eprom! cheers for that info

  • I’ve finally got myself a couple of these HR-16′s. Both units are pretty knackenred, but between them I’ve managed to build a fully functioning machine (and a ‘pre-knackered’ prototype machine with no buttons or LCD)…

    Anyway’s – couple of quick questions -

    Could you guys point me in the direction of the service manual? (The link to Jesse’s site near the top of the page is busted)

    Where is the crystal located in the HR-16? I’m looking really closely and I can’t seem to see it anywhere….

    Finally – tried playing with the ‘PCM54HP’ IC next to the 2 big IC’s. Bad idea…. As soon as I touched it, got a loud noise and now all the drums are distorted. Tried refreshing the caps, shouting, clearing the memory and even swapping all the removable IC’s around from the other machine. No luck…

    Do you guys have any ideas on how to find and fix the problem? It was pins 5 and 24 which I touched with the wire (and a 1k resistor).

    It’s no big deal, as the whole point of a knackered prototype machine it to try potentially damaging things, right? It’s just a bit disappointing as it was the first experiment I had chance to try!

    ok, cheers again……

  • hi, the crystal is located near the biggest ic on the board it looks like a big blue cap, it is labelled Z1. i’m not sure about the chip problem though. sorry. good luck, maybe you could burn a new one or try and locate a replacement part?

  • Ah ‘big blue’ thing, Gotcha. I was looking for a silver thing.;)

  • Hello, i have a problem with my Hr-16. when i tap on the PATT butom i have the message : SOFWARE ERROR.. what’s this…?
    Can somebody help me please..?

  • Harold and Squidfanny-
    The service manual is in our manuals section.

    Harold, check the troubleshooting section in the back, and see if it mentions that error code.

    Squidfanny, as far as the PCM54HP chip, yeah, maybe you can find a replacement online. I was able to find datasheets on google, so hopefully someone has them in stock somewhere… And you’re not the first to blow that one up, apparently. I should make a new section on this page for the “danger areas.”

  • Hey
    watched the video of your new track, liked it and thanks for your previous help about hr16p.s.u. Have gathered almost everything i need for the rom swapping on the hr16 27c4001 chips, rom burner and i have a lap top and couple of hr16s. I’ve bent one and am trying to access the software for rom swapping, unfortunatly i’m unable to access robots in motion website via your link. Is there any way i can gain this software via email or could anyone help me please?

  • @clone2: it seems that all the sites with HR16 ROM images have gone down. I know I’ve got copies of them on a backup disk somewhere, so I’ll have a look tomorrow and put them somewhere.

    If you want to create custom sample ROMs it’s a bit more involved than just blowing new waveforms in. I’ve written a utility to assemble up new sample banks and alter the titles in the firmware ROM, but it’s a bit fiddly to use. I need to spend a bit of time on it to get it doing the “ticks to -128″ thing to shift down the bits and get better sound quality.

  • Hey gordon
    thanks for your reply, i appreciate what your saying about it being more involved than just putting new waveforms in, i just find it a really good idea and really wanna give it a try but it is a downer the web site is out of action, so i cant even see what is involved. You sound like you are experienced and you say you have written a bit of software, i would like to see this if possible (though if not no worries). If you could help me out in anyway it would be great as i feel as if i have hit a wall, and could do with bit guidance.
    mucho thanks

  • Take a look at the following links:

    Note that I now consider the method described for encoding the “gearshift” marker utterly utterly bogus.

    The long and short of it is this – the HR16 has its firmware ROM scrambled due to a hardware weirdness. This makes it hard to work out things like sample names unless you unscramble the ROM, which fortunately is pretty easy. The ROM also contains the start markers for each sample, so if you want to change the sample lengths then you need to get at the firmware ROM, and if you’re getting at the firmware ROM you might as well change the sample names too ;-)

    If you can hold off for a couple more days I’ll have a better writeup for all this on my website. The actual utility that does the sample-to-ROM conversion isn’t particularly well-documented yet.

  • clone2- It’s unfortunate that the robotsinmotion site went down. I only got to see a demo version of the program. Supposedly a full version was available for a donation. But the author was busy with school for a while, and then he abandoned the project after a while.

    Gordon has made some progress with this, however. And like he said, he was able to figure out how to change the sample lengths and names, which wasn’t possible before.

    Gordon- Looking forward to seeing the writeup!

  • Hey guys
    thanks for both replys, hope i dont sound impatient :), think i may have got the wrong eproms (i got m27c401k-15) they are 4meg so may try them anyway, but have 6 4001 on way that i sourced elsewhere so am only just getting my head round the process before i throw myself into it. Will defo check out the links Gordon, i’m presuming this is your site?, really appreciate you taking the time out, this seems to be the only site on the net that is discussing this, and it seems to go beyond circuit bending. do u guys use the hr16 on many tracks you write?
    keep pushin the boundaries amigo’s

  • Don’t worry about the ROMs – most of them fit the same pinout and only have slight differences in speed and programming spec. We don’t need to care about that here. The only really tricky one is the ROM for the TR-505 – haven’t forgotten about that, Justin – that needs a daughterboard to convert to the standard layout.

    I don’t get any time to work on music these days and I don’t have a lot of energy left to sit and work on things at the moment. Hopefully that will improve soon ;-) In the meantime here are a few things I did ages ago:
    Named after the bottle hit samples, it was done with a tape echo, a fuzzbox and a swept filter from my Transcendent 2000 synth – all the actual sounds were generated by the HR16

    Simple HR16 pattern (you can tell I like those tuned pitch kick drums) through a Peavy Deltafex echo unit with lots of feedback and tight “static flange” delay.

    HR-16 with custom sample set, generated with my utility.

    Feel free to nick samples off any of these. They are under cc-by-sa, like all my samples. If you ask nicely I might let you use them under cc-by ;-)

  • nice samples dude, the bottle has a strange hypnotic quality was this a sound on the custom rom on hr16? and the second is a thumper, my kinda music, shame you don’t have the time to do more, but i know what you mean, i’m just getting back into writing, taken three years out while i’ve been twisting machines circuits and now i feel ready to write again. How do ya upload samples onto this site? would quite like to let peeps hear what i’ve been doin.

    easy now

  • The first two tracks were done using stock HR16:B ROMs in the HR16. There’s an Alesis ROM which is the HR16:B version 2 software, but set up for HR16 sample ROMS so you can upgrade your HR16 to the improved software. Once I get my page about the utility up (I’m working on it, I’m just busier than I’ve ever been in my life now that I’m unemployed, weird that) I’ll explain the differences – you need the HR16:B ROM for the tool to work.

  • And i’ll upload the firmware and sound ROMs here, i’ve been meaning to do that. They’ve been available on other sites, but it seems those sites are down now….

    clone2- you should be able to post a url to your mp3, and it will show up in a little flash player, like in gordon’s comment above. Email me if you don’t have a place to host an mp3.

  • good work, you guys have given me alot of food for thought. I’m bit rubbish on i’net this is thie first forum i’ve replied to, and thats only cause what you guys are doin is so interesting.
    Justin will email you about gettin some mp3′s up-the music to your new video is really good, thought you’ve got a new sound, was quite taken aback when i heard it, really weird in a good way.

    So gordon basically i need to be burning a couple of hr16b roms then i can start to consider maybe using the firmware will keep eyes on your website. HR16b is that the electronic drum set? are the sounds quite different than the accoustic sounds of the hr16-am interested to hear them anyway.

    the input from you both is appreciated THANKS

  • The HR16:B ROMs have newer firmware (can’t remember the exact differences to the user, but in general it seems to have better timing – there are *huge* differences in the internals though), and a slightly more useful sample set with a lovely long 808 boom (RAP KICK, they call it) which is what you hear on the first two tracks (through a fuzzbox on the first one). You need to make a set of all three ROMs, otherwise the samples won’t match the pointers in the firmware and it will just be weird.

  • when you say 3 roms do you mean the firmware as well?, sorry i’m bit confused thought there was just 2 roms…

  • There are two 4Mbit sample ROMs and one 256kbit firmware EPROM. The EPROM is the one with the window, beside the RAM and CPU.

    Incidentally, while bending the HR16 it’s best to just stick to the two big 32-pin sample ROMs – shorting pins on the RAM, EPROM or CPU will just crash the machine and lose all your patterns. Stay off the big square ASIC and the PCM54 DAC too, particularly the latter which has 12v supplies that will zap all the other chips!

    With sample-based “toys” most of the fun bends come from corrupting the way that samples are read from memory, so it’s best to stick to the sample memories ;-)

  • Hi guys. I’m just finnishing off my bent hr-16 and it sounds great….:-))
    Precision oscillator really twists it..

    I’m just wondering if there is a way to change the velocity curve of the pads? It’d be nice to get a little less sensitivity sometimes, as I can’t make too much noise at night in my house.

    Also, have you guys looked for triggers yet? Where would be the most likely place to probe, or is it not applicable in the hr-16?


  • Nice. I recently got a couple of those oscs from getlofi, so hopefully i’ll try them out on the HR-16 soon. I’m messing with the tr-505 at the moment…

    The pad velocity can be tweaked under the midi setting menu. I’d set it to the maximum (so you don’t have to bang as hard), turn the volume down, and listen thru headphones. =]

    Triggers- do you mean in or out? I would just use the midi, personally, because midi is a big part of my setup. If you’re talking CV out, it might be tricky. Take a look in the service manual. I have a feeling it’s not as simple as in the tr-505 (which has 8 separate channels that you can tap triggers from). Since you can assign any drum to any output in the HR-16, i think it’s all governed by the CPU. I don’t think you will find cv triggers for each drum. You’re welcome to prove me wrong, though!

  • The pads are part of the key matrix. If you wanted to add extra triggers you’d need to have a transistor across the keyswitch, or an analogue switch possibly. To trigger, you’d fire the switch and feed a pulse to the analogue input that the piezo pads use to detect velocity.

  • Yea, triggers out. I was hoping to use the hr-16 to sync a squarewave/vactrol synth which I made. I used a 4049 to distort an audio source (drum machine) and used the distortion to drive the synth. It works quite well, but when the bends are active it tends to destroy the sound a little too much to get clean sync.

    I was hoping that a trigger pulse would be cleaner.

    Gordon, I think I understand what your saying. If I did this mod then I’d have a velocity sensitive trigger right? That could be quite a useful mod, but would it let me tap the sequencer?

  • No, that wouldn’t let you control an external device.

    What you could do is use one of the audio outs and set one sample to use it, then detect the audio from that output. Another thing would be to make up a little microcontroller board with a MIDI in and trigger outputs.

  • Hello again. Thanks for all the help and advice, I have now finished my first HR-16. It sounds great and looks pretty sci-fi too.

    Here are some pics. Sorry about the ‘retro’ picture quality, I’m eagerly rinsing the last few drops of life from an old camcorder, so that I can justify ‘bending it when it finally becomes completely un-usable…. Also recording some youtube vids, in case you want to hear the precision oscillator.

    hr-16 4.jpg – 0.51MB

    hr-16 2.jpg – 0.53MB

    hr-16 3.jpg – 0.52MB

    hr-16 7.jpg – 0.54MB

  • Crazy! You can light up a whole room with all those LEDs! Are they connected to the sound roms? I checked out the youtube vids. (when did youtube upgrade to STEREO?) The getlofi osc is a nice addition. I’m curious if the tempo will stay constant if synced with midi, have you tried that? (btw- use html, not BB code to link to images- i fix’d it for you.)

  • Hi, sadly the precision oscillator doesn’t really work with midi. In fact any more than a couple of semitones out of stock and the midi won’t work at all.. Maybe there’s somewhere else on the hr-16 where the oscillator could be fed into, like on the 505?

    The LED circuit is from an old x-mas decoration, slightly re-wired to give a more random effect.

    Thanks for fixing the photos, as usual I got a bit carried away. I guess one photo would have sufficed….

    take care…….:-))

  • That’s because when you slow down the CPU clock, you slow down the UART clock. If the clock was 1% slower then you’d have MIDI running at around 30940 baud – no way is that going to work!

    Perhaps you can clock the ASIC separately, or clock the board from the VFO and keep the CPU clocked at its normal rate.

  • Hey guys a little help please.

    I just got my hands on a hr 16B and i’m having a bit of trouble with it.

    the top row of pads don’t seem to work correctly, the first (tom 1) is functioning as the pay/stop button and the other 7 (ending with perc 2) will not play or respond. UNLESS the sequencer is on/playing then the pads function in a strange way. example: press =sound, press again = no sound. press once more = sound. etc…(bottom 8 pads function as normal always).
    only while a pattern is playing do the top 8 keys behave like this. when the sequencer is idle none of the TOP pads will function save for the first (tom 1) which always functions the same as the play/stop button.

    I own a grey HR 16 and know it pretty much from top to bottom. so i have tried everything i know about it on the HR 16B but no luck, even the fac reset doesn’t seem to have an effect on the top 8 pads. I keep thinking it may be MIDI related but the fac reset returns all functions to normal so that can’t be it.

    does anyone know if this is some feature exclusive to the 16B?
    and if so how to disable it?

    any help appreciated.

  • It’s a bug, not a feature.
    It sounds like either the conductive layer on the rubber pads under the buttons is wearing out, or one of the cables that connect the button matrix to the board is bad or connected wrong. Most likely the latter. (HR-16B was built with better buttons, altho, i’m sure they can wear out.)

    Usually when buttons are triggering the wrong functions, it means something is wrong with the button matrix. It’s very easy to connect the cables wrong, they don’t have tabs to prevent you from doing that, they’re just plain headers. So whoever had it before you, might have opened it up and then didn’t re-connect the cables correctly. Or a cable could be bad. You should test the continuity of each wire.

  • Thanks for your reply. I think it’s a problem with the main board, I have 2 other grey 16′s, so i played a bit of musical parts. nothing wrong with the eprom, sample roms,keypad pcb,ribbon cables. So its the only thing i can think of. I don’t know enough about electronics to try for a repair. so now i have a fully functional 16 and 16B and one 16 with 7 dead pads and 2 start buttons lol. What with the HR’s being completely reconfigurable it’s no biggy since it can still be fully programmed and used as normal.

    hey i posted a question on the tr 626 page, i would a appreciate your help on that as well.

  • Hmm, that’s weird. If you can get your hands on a multimeter, you should test the connections on the board after the ribbon connectors. There may be a broken trace, or something shorting.

    Well, it sounds like you can still control the HR-16 with midi? So it’s not a total loss…

  • Hi, I’m having problems switching eproms. I have one piggy backed on U15, with pins 22 lifted and switched between 5v and ground with a dpdt and it switches fine. When I add IC U16 the sounds from that rom are choppy. If I take U15 out U16 works fine. Hope this makes sense.
    Any ideas?

  • What you’ve done would work if the HR-16 (or other sample-rom drum machine) only had one ROM. But the 2 original ROMs in the HR-16 are piggybacked already! If you look, the 2 chips’ address and data pins share connections. What happens, is their /CE pins are rapidly “flip-flopped,” so that only one ROM is active at a time. That’s why you hear the chopping sound.

    So- pulling the /CE pin HIGH (5V) on the chip you want INACTIVE is correct. But you need to connect the /CE pin on the chip you want ACTIVE to the pin from the SOCKET (not ground), so that the rapid flip-flopping can occur.

    Is that clear? Let me know if you get it to work!

  • Thanks for the reply. I tried it with 2 chips on U15, one the original the other the custom. I used a 1k resistor as the pull up from the 5V. I connected the two wires from the pin 22′s to the 22 of the socket. I used dpdt to control the switching. It kinda worked, but when switched to the original chip some of the sounds from the custom rom still remained, but a bit distorted/choppy, sometimes blending in with the original sounds.
    Am I missing something with how U15 and U16 correlate?
    Cheers in advance!

  • Hmm… Maybe you need to toggle the /OE pin (24) instead/also? It’s been a while since i experimented with this…

  • Hi,
    so several hours and eproms later I’ve got it working.
    The problem seemed to be that I was using the same pull up resistor for 2 eproms. This must have created a short between the C/E’s that caused the screw up. So now I have 4 separate resistors, 1 for each eprom and 2 spdt to determine which eprom is being used. 1 switch for U15, the other for U16. Cool. Cheers for the help!

  • Ah, great! Glad you got it working. If you get a chance, send a pic!
    Also, feel free to send mp3s of the custom sounds, or if you want to share the ROM file too, that would be great! I’d like to post different people’s custom ROMs here.

  • yeah, once it’s enclosed i’m gonna make a video.
    i’ll email you the mp3 and rom files as well.

  • Hi! I just bought a HR-16, but it tells me that there is a software error 01, does anybody know what that means?

    Some other problems for me:
    When I choose a pattern and start it, the clock begins, but no sound appears.
    When I hit the pads the sound works.
    I´m new to midi but when I connect it to my MicroKorg it doesn´t seems to get any midi!

    I haven´t started to bend it yet:-(
    Please help!

  • @Thomas – try doing a factory reset by turning the HR16 on holding down RECORD, ERASE and DELETE. If that doesn’t do it, you may need to change the internal battery. Not a big job, but fiddly enough that you’ll want to be reasonably proficient at soldering.

    You *are* using an AC 9V power supply, not DC, right?

  • So you just bought it and it’s defective? Bring it back and demand your money back :P Uh

  • hey-any peeps soldered terminal wires on an internal battery? how safe is this, anyone lived to tell the tale and still alive to give advice, should i wear a welding mask….

  • I watched my buddy solder wires to 2 AAA batteries and either he sucked at it (he never really did get good at soldering) or its more difficult than it looks because it took him a while.
    I have not had to do it yet, thought i can’t see it being to much of a big deal. nothing exploded anyway lol

  • It should be safe, but tricky. When you solder to some kinds of metals, you’ll need to use rosin flux. Rosin-core solder has some flux in it, but for soldering to things like batteries, you’ll need to use extra flux. I’m not exactly sure why… something to do with an oxidization layer on the metal….

  • thanks for that just waiting for batteries to arrive (direct replacement for hr16 internal batteries is lithium ER14250 i just got 5 for 13quid from toptechbattery.co.uk in case anyones interested, the guy said i would need to order a 1000 if i wanted terminal wires on them lol)
    many thanks for your help guys will let you know how my battery replacement goes..easy now

  • Hey are you sure about that battery?
    what’s the MA rating on those?
    I ask because i would rather purchase the Tadiran TL5101 which is the exact brand and model used by alesis from TSEelectronic (with leads on it) but they suck(TSEelectronic), they have too many rules to purchase from them. I found the model/brand you listed on ebay with leads for about the same price but i have had bad luck with the hong kong guys before. I don’t suppose Burnkit has a couple they could sell me?

  • We don’t have any extras. We’ve ordered from Mouser in the past. Yes, Tadiran TL5101 “1/2 AA” 3.6V lithium. They will only ship US ground, however. Apparently there are some new regulations about lithium batteries on planes, now.

  • It helps if you scrape some of the shiny coating off the ends of the batteries, and use a 25W soldering iron. Don’t heat them up too much, or they’ll burst!

    3V is perfectly fine from two AA batteries, although if you use new lithiums you’ll get something like 3.4V.

  • Hey bent apparatus as far as i know they are a direct replacement for the original batt that are in the hr16 found this info on net (dont have the ma rating of hand. Waiting for batteries at mo will post when i have more details. Toptech battery accept paypal as well. I tried to run memory off two aa batteries and it didnt work. Cheers

  • Greetings…I was trying to find an HR-16 emulator, basically a PC version of the ol’ workhorse, I’ve had mine so long I’ve forgotten how long I’ve had it, I think it was a year after it was released, will hafta check the version next time I power it up.

    I was bummed when nobody has emulated it yet, might be a neat project for some bored programmer (HINT-HINT)!

    I freaked when I actualy found a PDF of the SERVICE MANUAL, just googled “HR-16 manual” and scrolled down a lil.

    One of the mods I was planning (I wouldn’t mind finding an MM-T8) was to mount a piezo or other small low-power speaker and a switch with an LM386 amp chip tapping from the power supply, so wouldn’t hafta hook up an turn on amp(s) just to hear it or for practice.

    Also planned a pair of LM386 chips and a headphone jack, wouldn’t mind finding a couple more HR-16′s (like a B or something), they’re the sweetest DM I’ve ever worked with!

    Just another hint for proggers, challenge to make a freebie EMULATOR, that pretty much looks like top view of the HR-16, and acts pretty much the same, not hard to grab samples, also wouldn’t mind same emulator to have ALL sounds avail (HR-32SW?), meaning more than 16 pads on the front…maybe make an iface for HID’s for custom pads?

    Just an idea! Enjoy!

  • back again with the info, my sweet lil HR-16 is a version 1.09, and the date on it (QC tag on bottom) reads 1989, I think I got it around ’92, had it ever since…hadta clean the pad contacts at least a hundred times, and SO wanted to build an amp into it.

    BTW, it was used for ALL drumtrax on my album (check website), available for free, feedback wanted, keep in mind those were recorded onto a cassette multitrack master mixed to chrome cassette and then after a decade was digitized…

    Since I have the ORIGINAL programming, I have now directly digitized the drum trax into a digital multitrack, will be working later on to add bass, guitars and vocals (PLEASE HELP ME DECIDE WHICH SONG FIRST!), and eventually remaster my songs from the ground up.

    I’ll also hafta relearn how to make new drum trax again, and recently I heard the B’s samples an I -=SO=- wanna make an (PUN INTENDED) “A/B” switch ;)

    Thanks for the service manuals an such from here, muchmuch appreciated!!!

    When I find another job, I’ll want to buy the B sound chips, and possibly even the newer version(s) of the OS chip(s) as well.

    Once again, thanks for this site!!!

  • I like your idea of installing an amp and speaker. And if you’re going to do that, you should make the HR-16 battery powered! I think Graham over in the MMT-8 forum was talking about converting the MMT-8 to battery power a while ago… Both machines take 12V AC power, but apparently, that gets converted to 12V DC somewhere inside, so it IS possible to run it off of batteries with a bit of modding…

    An “A/B” switch is very do-able! One of our visitors, al, just did that with some custom samples. You need to piggyback the 2 sets of ROM chips on top of each other, but connect their /CE pins to a toggle switch.

    Soon, i want to have ROM chips available here, and I’d like to come up with a little board that makes the piggybacking easy…

  • I’ve been bending my SR-16 with glee, but I think I blew the DAC. No matter – I found the pinout for it online. It takes 16 bits and outputs the result as a voltage which is given to it over +Vcc and -Vcc pins. I think Alesis may have opted for a 9v AC supply to make this bit much easier. Now that is only 16 bits on one channel, which may seem strange when you bear in mind that the unit has (and outputs) stereo samples. The signal is then passed to a MOSFET amp then through a 4-channel audio demuxer, for Line Out and Aux Out.

    My plan now is to build a daughter-board which will take the 16 bits and pass them through its own DAC and Demux, at which point I can do other things with the signal. First on the list will be bitshifting prior to the DAC.

    A side plan is to move the sample chips to another daughter-board and burn some fresh ones, with a selector switch, as well as adding an 8-bit ADC (when throwing 8-bit data into a 16-bit system, setting the LSByte to the same value as the MSByte doesn’t hurt!) This app also peaked my interest: http://www.namesoft.biz/sr16editor/index.htm

    I’m going to have to add to the SR-16 case to make it big enough, but that won’t be too difficult. Decoration will be a steampunk theme – brass, big rivets, cogs… Planning to rebox a Zoom RT-123 in a similar fashion with the red LED display behind a round smoked glass lense. I’ll update you when I’m done :)

  • That sounds sweet, Hugh! There needs to be more steampunk circuit benders! =] Looking forward to seeing what you do. Any SR-16 mods should also apply to the HR-16 for the most part. Keep in touch!

  • I’d be interested to see a dump of the SR16 ROM, to see if they do the same trick as the HR16 ROM.

  • Gordon, i can send you that. I had a little success changing sounds around, but it’s not as straightforward as the HR. The SR uses stereo samples, so there are “left” and “right” samples. Also- the SR has pseudo efx like reverb. So there will be a “clean” sample and a “wet” sample that gets mixed in when you select the drums with reverb.

    Are you up for the challenge? =]

  • HR-16 and SR-16 ROMs posted! (see above)

  • Yeah, it looks like it’s Christmastreed like the HR-16 ROMs. More once I get a chance to dig in properly.

  • i def want to bend my hr16 but dont trust myself enough. but i saw that yall are taking on projects and was inquiring about you guys at burnkit could do it up for me. please contact me if you still have my email with pricing and a time frame thanks!

  • Nice job, Dmitri! Where did you get those segment LEDs

  • I’m working on a replacement HR-16OS to better support custom sound roms. So far I have the machine booting a 8051 debugger. Please check my HR-16 page if you’re interested in the details:


    I’ve offered a DOS tool to decrypt the OS rom to change change the exiting one or to create your own.

  • Very cool, Mike! Have you been able to change the drum names or lengths yet?

  • @Mike: might I draw your attention to http://www.nekosynth.co.uk/browser/utilities/hr16utils

    It’s already possible to change the drum names and lengths ;-)

  • Yes, changing the drum names and lengths is fairly simple once the OS is decrypted. My goal is to be able to do this all from the machine and have the OS re-flash itself. The ultimate goal of the bent OS is to have a drop replacement for the old OS which is more “bending” friendly so it’s a lot more than just modifying the values in the old OS.

  • hey,
    my hr16 lost all pattern content after turning off. i´ve changed battery, but nothing happend. Same error. I found the service manual and did a diagnostic on the machine, and it seems all ok. Any idea ?

    cheers, neon

  • Neon- You might need a new SRAM chip. Read this comment for more info. I think i still have a few extra chips. Email me if you’d like to buy one.

  • I am assuming I fried my chips. I did this around 4 years ago without the info I know now on bad points and one day it died.

    The first month of it not working it had an underscore only in the display. And now it has nothing but is lit up.

    Battery reads fine.

    Is anyone selling replacement chips that work? Really love this drum machine and after a year of not having it usable I am going nuts.

  • hi, just got HR-16B for US$5 [with no it's own power supply]

    so i buy 9V 1A *AC* adaptor, and plug it into HR-16B. switch the power on, and…*tada* LCD is blank, all LEDs are lights up :(

    what should i do?

  • [...] I was pretty excited to read this very informative thread which explains just how easy it is to warp the HR-16 / HR-16b to get a huge variety of distorted, [...]

  • Awsome what you’ve done. My HR-16 has been in the garage for many years. I pulled it out and it lights up but no audio. Could replacing the battery fix it or any other ideas. I would love to get it back working, then maybe look into bending ;)

    Thanx much!

  • The battery is only for pattern memory, it won’t affect sound.

    Are you sure it’s playing back patterns? When you test the pads out, make sure you set their velocity to fixed, otherwise, if you tap them lightly, they won’t produce a loud sound.

    Try the self-test mode from the service manual, and tell us what happens…

  • Thanks for the quick response.

    I opened it up and re-seated the multi pin connectors and presto! It works, just no pattern memory. Next, get battery, then get to bending!


  • Hey, just wanted to say thanks for the great info. I’m working on bending an HR-16B, and have run into a bit of a problem. I wired up the 28 non-risky points (as discussed on this page and on Electri-Fire’s site: http://www.electri-fire.com/alesishr16.htm) on the two EPROMs, and it was working fine for a while. Then it started just rebooting over and over. I removed all the wires, but now the machine still sounds bent – the samples all sound distorted/bitshifted.

    My theory is that either:

    (a) I fried the EPROMs, in which case no big deal – I want to burn some new ones anyway;


    (b) There’s a short somewhere. I’ve checked the visible solder joints, and there are no bridges. However, the unit I’m working on is from the CA revision, which is a four-layer board. Is it possible that in the process of wiring up to the EPROM holders, I burned through the substrate and somehow shorted together some of the traces INSIDE the board? In that case, I guess it isn’t coming back.

    I guess it’s also possible that some solder melted through and shorted out some of the legs of the EPROM holders on the component side… again, does that sound like a realistic possibility?

    Any help offered would be greatly appreciated.

    PS – in my efforts to fix the resetting problem, I located the elusive C20 which is mentioned in the service manual. On my unit, it’s a red, sqyare cap, with one side labeled


    and the other labeled


    Looking at the component side of the board, with the jacks facing away from you, C20 is near the bottom left. On my board, it’s immediately to the right of a blue, similarly-square cap, which is labeled C16 on the screenprint on the PCB. Hope that helps.

  • An added note – on my HR-16B, when I’m recording a pattern, the click sounds really distorted and growly. Is the click stored on the EPROMs, or not? If not, would this suggest that the problem might be with the DAC?

    Thanks again!

  • Sked-
    There is a fix for that problem mentioned in the service manual: “7.17 AQ reset threshold.” It happens with the later model boards. I only had to solder a new resistor in parallel with one on the board. This fixed the reset problem, which was happening any time i had 4 or more bends activated.

    The click is one of the drums, you can set which drum in the menu. If it is distorted, you can try adjusting the DAC. This is also covered in the service manual: “7.10 DAC Drift.”

  • Hi,

    I have a Alesis SR-16 and I would like to install custom eproms with own sounds in it.
    However, I don’t have the knowledge for programming the eproms.
    Can somebody burn these eproms for me? I will pay gladly for the service.

    Thanks in advance!

  • Hey again,

    Things got worse before they got better. For a while, I had the dreaded “blank screen with underscore” problem – when I would boot up, all I would see was an underscore in the top left character space of the LCD, and then nothing else would happen.

    Fortunately, I was able to resolve it by removing all my bending wires and then putting the HR-16 into “self test” mode. This involves booting up the machine while holding down the “QUANT” and “MIDI UTIL” keys. The machine boots into a diagnostic mode, and runs through a few tests. You’re supposed to hook up a MIDI cable from the MIDI In port to the MIDI Out one, and an 1/8″ cable from Tape In to Tape Out; otherwise, it’ll give you an error message and freeze. However, even if the machine doesn’t get to the end of the tests, I’ve found that the next time you turn it on it’ll boot fine. Hope this is helpful to some of the folks out there who have seemingly bricked “underscore” HR-16s.

    On a side note, the samples on my HR now all sound permanently scrambled/bent/bit-crushed/etc. Does anyone have any idea what might be causing this? Any idea if I fried the sample ROMs (in which case, say, new sample EPROMS would play normally) or if it’s some weird internal short as I previously speculated (in which case any new sample EPROM would also play bent-sounding), or something else?

    I don’t have an EPROM burner, unfortunately, so can’t sub out the ROMs and test for myself. Might go pick one up, though.

  • Stumbled across this site by accident, but hopefully Justin’ll be able to help me…

    I got an HR-16 a while back, and I’ve barely touched it because of the 2 very irritating problems it has.

    1) The sound is very distorted & quiet. I tried adjusting the internal trimpot like the service manual suggested, but that did nothing. I’d be fine with the distorted sound, if it was at least audible :D

    2) The unit doesn’t turn on unless there’s a lot of pressure applied to the power supply (i.e., the 9V jack on the drum machine itself). I’m thinking a replacement would be in order, but I can’t find any place that sells said power jack (or I’m not looking for the right thing…).

    I’d really like to be able to fix it, so that I can then screw it up & bend it :D Any suggestions? (If anyone;d be able to help, get in touch with me at aroman12345@gmail.com)

  • Alex- about the sound output:
    Have you tried using the alternate outs? Same deal? And make sure you have the velocity sensitivity turned off, and “fixed volume” set to the highest setting when you test.

    About the power jack-
    It probably just needs to be re-soldered. Touch up those connections with some fresh solder.

  • Thanks for the reply, Justin. It’s the same on all outputs, so I doubt it’s a problem with the outputs themselves. After reading the manual again (just for kicks), I think it might be a problem with the DAC chip itself, as that’s the only logical thing that it could be. But I have no idea where to get a replacement; any suggestions?

    I’ll try touching up the solder points, but it might need a new jack altogether. If you know any places to get a replacement for that too, it;d be extremely helpful as well.

  • Never mind; I found a place online that sells them for under $30. Might have to pick one up, in the hopes that it’d solve the problem. (If it helps my case at all, adjusting the trim pot next to the DAC didn’t change anything either.)

  • Ok, let us know if replacing the DAC works. As for the power jack, i don’t know where to find an exact match, but you could try replacing it with a panel-mounted one (as opposed to the board mounted kind). Or, if you’re lazy, you could just hard-wire the power supply to the board.

  • Panel mounted would probably be a much better idea. And I could even replace it with one of those standard Boss adapters; would make my life way easier. As for the DAC, I won’t be able to test that for a good month or so; the only place I found that sells them at reasonable prices seems only to deal with small businesses & industrial people, so it’ll be a while till I find someone willing to get me one.

  • hey ive got an sr-16 on the way and im prepared to hack in some of my own samples. question tho, if the sr-16 has psuedo-fx;would switching reverb on and off switch samples? say if i replace the dry snare with and amen snare and change the wet snare to someone saying BREAK, would they switch between the two?

  • I have to add to this five-year rolling comment party to say that this page saved my sanity the other night. I’d received a 16B, never had one before, and I’d fallen foul of the ‘wrong adapter’ problem mentioned somewhere above. Sure enough, everything was working as it ought to – pad response, sequencer, MIDI – except the sound output, and when I arrived here via Google and read about the adapter error and found the right kind, the sounds appeared and all was well.

    Still, I had some exciting moments with the gain on my mixer ramped up to full, detecting a faint beat behind the fuzz and knowing that if it suddenly started working I’d be deaf for a week.

  • Hi, I got a Hr-16 that is unbent which has a problem when i turn it on. Every time i turn it on and play the drums on the machine within a minute or two theres this loud alarm sound that comes on which is really loud. The only way to stop it is to turn off the machine.

    I did the “Self test” and everything seems to be ok. All the pads seem to be working fine.

  • That’s very strange, i’ve never heard of that happening before. Can you take a video or record an mp3?

  • I think i may have found out the problem. The person i bought it off of gave me a 16VAC adapter. I ordered the Alesis P3 adapter and will be getting it on 09-15 so we will see if that fixes the problem.

  • So the problem is fixed with the Hr-16! The problem was that the 16vac power pack was sending too much juice into the machine causing it to make that alarm sound.

    Now i can start bending it!

  • Someone else had a power supply issue a while back. The HR-16 was acting weird, and it turned out they were using 12V DC instead of AC. Interesting that the HR-16 still functions partially with the wrong PSU.

  • I just tried piggybacking and using CE to select chips.
    It does NOT work.

    The disply indicates that the different firmware versions are being selected, but the sounds does not work.
    I only get some strange and weak sounds which doesn’t sound right at all.

    I broke the CE pins on the ROMS during testing so I’m unable to try other things right now.

  • The reason why it works partially with 12VDC instead of 9VAC is that when you use 12VDC you’ll still get the positive internal voltages, but the internal negative voltages from trhe regulator will not be present.

  • The sound roms have /CE pins, not CE. You need to pull the inactive pins high, and ground the active pins. Check out Al’s comment about how he got it working.

  • Sorry for the typo.
    I meant /CE (low active).

    Someone said that I should rather use the /OE (output enable) pins for selecting ROMs.
    Does anyone know if that may work ?

    I also used the same pull-up resistor for 2 ROMs.
    Gonna try using 4 resistors and a dual switch.
    Have finally got the new ROMs so it’ll be tried out tomorrow.

    But what is the “spdt” that menations in that post ?

  • I miss an EDIT-button.
    What I meant to say was: What is the “spdt” that Al mentions in his post ?

  • Hi does any one know where the Pitch bend is located? I saw on this video at around the :43 seconds into the video they start to bend the pitch of the instruments but keep the tempo the same.


    I got most of the Hr-16 bent but trying to find this one.


  • The pitch is controlled by the crystal. It clocks the samples. It’s a bit hard to find. It should be next to the longest chip on the board. It’s either a small blue or orange component that looks like a capacitor. It’s labeled Z1. It can be replaced with an oscillator such as the LTC1799 from getlofi.

    In that video, it looks like they hooked up a toggle to switch between the original crystal and the new oscillator.

  • Has anyone tried soldering 9 volt battery snap to the hr-16 so it can be portable? Is it even possible?

  • I wouldn’t think it would be possible, since the HR-16 power supply is AC, not DC. But apparently it IS possible, according to this thread. I’m not sure if the info is posted anywhere, tho, the MMT8.com forum seems to be down…

  • Please use your radical skills on an sr-16 and post the results, I cant seem to get my BIN file the same after i export it(yes i am aware this is an hr-16 doc) that would be awesome

  • Heh, ok. I’ve experimented a bit with the SR, but it’s a bit more tricky than the HRs. The process is the same as for the HR-16, but the samples are a bit more complex (stereo samples, reverb only samples, etc). When you play with BIN files, try opening them as RAW files, and be sure you save them with the same settings as you opened them with.

  • Thanks to everyone here for the awesome guidance! I just finished my soldering (chip bends and an oscillator pitch bend). I’m sure you saved me from wrecking my hr16!

  • hey guis,
    so im used to bending equips with a battery power supply and the ground is very easy to find. however, the HR16 is not, and im scared of connecting the + instead of the ground (which would obviously cause some srs problems. i see 3 spots by the power-in, but i lack a multi-meter. can anyone tell me which of these is the ground? also, im building in an external oscillator for a pitch bend that requires +5v, would it be a good idea to use the +5v from the chip for this? would that cause any problems?

  • I would avoid the power jack, since it’s AC, not DC. Ground can be found in many places on the board- pin 16 of the EPROMs, the negative battery leg, sleeve connections on all jacks, etc. You should be able to tap the 5V from the EPROMs, too. Unless the clock circuit draws too much current, but i think you should be ok.

  • Yeah, I used the sleeve connection on one of the jacks which works fine.

    However, I had trouble with the +5V going to the LTC1799 oscillator. There are many places on the PCB where you can tap +5V, but every location I used would cause the HR-16 to misbehave. Mainly the problem was with the LEDs; when I powered up the HR-16 after connecting the 1799, the LEDs would either not light at all, or some would light when they weren’t supposed to. When I disconnected the +5V from the 1799, everything on the HR would work normally again. I know the 1799 was wired properly because the pitch control worked fine when powered by battery.

    Anyway, I gave up for the time being. I know several folks here have successfully added the 1799 pitch mod to their HRs. Any info you can share with us? Thanks.

  • I just aquired an SR16 on the cheap. and I get distorted sounds on every pad,
    I’ve spent about 4 hours trying everything. I have come to the conclusion that
    it needs to be opened up. I was wondering if anyone had any experience with
    repairing these and if so could you point me in the right direction?

    this is the response i got, and i’d liek to know if this sounds right to all of you, and if the sound chips in the SR16 are socketed or if i have to desolder them to clean them?:

    The problem is probably caused by dirt / oxidisation / dust on the sound chips
    causing sample data to be

    decoded incorrectly

    Open up the unit and carefully remove the two large chips containg the sound
    sample data from the sockets. You can

    do this by carefully leavering each end of the chip with the tip of a flat
    screwdriver pushed between the small gap between
    the chip and it’s socket. Once removed, blast the empty chip sockets with a can
    of air duster to blow out any dust. Carefully
    push the chips back into their sockets. Do this slowly, making sure the chip’s
    legs do not get bent. The act of re-seating the
    chips in this way means that any oxidisation, dirt or dust on the legs of the
    chip gets scrapped away and a good good connection
    between the chip’s legs and the holder is again formed. This is a well known
    failing of chip sockets… especially old ones.

    let me know what i should do please

  • Did alesis give you that response? Yes, i would follow those directions. The sound ROMs are socketed, and so are a few other chips. Make sure they’re properly seated in the sockets when you replace them. If they are damaged, i can sell you copies.

    Now- when you say “distorted,” does it sound like the circuit bent examples on this page? Or just really loud, like it’s running thru a fuzz pedal? If it sounds circuit bent, then check the ROMs as described above. But if it sounds distorted, it could be the amp or volume pot. I have an SR-16 with a bad volume pot- i have to turn it all the way down to get a normal signal, if i turn it up just a little, it distorts like crazy. I haven’t fixed it yet, because i sort of like the distortion! And it’s led me to do distortion mods on the HRs as well…

  • I guess I am missing something because the sound chips on my SR-16 don’t seem to be socketed. The volume pot is scratchy already and doesn’t seem to affect the level of constant fuzz going through the signal. No matter what volume level i use, it’s still fuzzed out. I’d like to check the sound chips but they look soldered in to me. I don’t know what to do at this point.

  • Maybe I am missing something but the sound chips look soldered in to me. I don’t see any sockets on the board other than for the pmc54hc chip and the DM3 chip. The distortion is like a fuzz but its not the same distortion that comes from the volume pot. At this point I don’t know what to do. I’d like to check the soundchips but it looks like they are soldered on.

  • That’s strange, on my SR-16, all the larger chips are socketed. Even the OS chip, U3, is soldered? That doesn’t make sense… Sound roms are U5 and U6. Did you try gently prying them up?

    Have you tried using the alternate outputs? Are they distorted as well?

    The PCM54HP chip is the same DAC that is in the HR-16, and people have told us they’ve “perma-bent” their HR-16 by messing with that chip. So there’s a chance your SR-16 was damaged by the previous owner trying to circuit bend it. You could try replacing the PCM54HP. Damn…. they’re pretty expensive. It might be the PCM chip, it might not. Supposedly there are higher voltages in that chip than the normal 5V logic levels, so if someone did try to circuit bend it, voltages from that chip might have damaged itself, the sample roms, or some other component.

  • http://blog.h34th.net/2009/07/circuit-bending-alesis-sr16.html

    that is what the inside of my sr-16 looks like. I don’t see any sockets on the soundchips.

  • Hmm, yes, those are soldered directly. Strange. I wonder if that’s something Alesis decided to do later in production.

    Did you try removing the PCM chip and cleaning/checking to see if any pins are bent or not inserted correctly?

  • I have been puzzling over why oh why i cant get the backup memory to work in my hr16.
    Battery has been replaced but mo life in the beast in the memory department . has anyone else had this issue? Could the memory have failed? any ideas on how to restore its faculties greatly appreciated. I also have the same issue with a Casio RZ1 and have replaced backup batteries before with success..

  • Sounds like you need a new SRAM. We have them for sale here.

    The patterns and settings get stored in the SRAM, and the battery keeps those settings alive when you power the machine off.

  • Thanks for the response. I was under the impression that if the SRAM was gone then there would be no ability to swap between patterns,chain songs of patterns you have made etc when the unit is on. This is not the case as the unit functions perfectly normally when it is on but you lose everything you have composed when you power off.
    The same goes for my RZ1. I have attempted battery replacements in both but no signs of holding memory. The batteries are both fully charged brand new and of the correct type.. Is there anything more i need to do on these units other than just soldering in a replacement? Perhaps the SRAM is the culprit.

  • If the HR-16 works perfectly while it’s on- you can save patterns, move from one pattern to another without losing changes, etc., but loses memory when you power off, then that sounds like a battery problem. But you say you replaced the battery with the correct type. Are you sure you observed the correct polarity?

    I’m not as familiar with the RZ1, if i can find the service manual or schematics, it may have some answers…

  • Yes polarity is correct for sure.. i have re visited this issue a few times without resolution.. I have had the HR 16 since i modded it with a patchbay way back in 2004 refurbished the contacts etc.. but the battery backup has always been an issue with the unit. I have ordered a new SRAM to see if this is any help but I’m inclined to think something else is going on.. all i have done as far is swapped batteries like for like.

  • I just checked the troubleshooting guide in the service manual, and found this:
    “Not retaining memory when power removed. (No battery backup. Battery is not dead.) -> Faulty reset circuit (not going into reset during power down). -OR- Faulty SRAM.”

    There’s also something about a faulty SRAM capacitor- but this causes the battery to drain and die.

  • Hey Justin,

    Yes i re visited the manual and remembered that on testing R 97 i get a reading of 2.1 v way above the 80mv that it should read.. obviously the sram did not help in this matter and the memory still wont function .the battery reads at 3.6v still.the new sram made no changes.. poss a fault on the mem power line… mysterious hope i can eventually solve the puzzle i wonder if anyone else has had similar troubles?

  • I’ve got my hands on an hr-16 with the same problem that someone has already mentioned. Output is SUPER quiet and distorted (in a weak fartish sort of way)Because the service manual lists the dac as a possable cause of such a problem i went ahead and ran the self diagnostic but when it gets to calibrating the dac offset it never tells me its done. Is this normal? should I let it run overnight?

    If I do need to replace it, I think i have another dead hr16 laying around somewhere to swap parts with but honestly I’m having trouble figuring out what the chip looks like. Can anyone tell me where to look on the board or tell me what it should be labled as? I’ll let you know how it works out.

    Wish I had something to add about burning new roms for the thing but I don’t know shit about computers. Anyone have samples of custom roms being bent on one of these things? would love to hear them

  • ok so DAC = pcm figured that out. Switched the chip but it didn’t fix the problem. What I ended up doing is making my own output using ground and searching for a place on the chip that was sending a usable signal. I think the leg I used was 5th from the top right if you are looking at the IC so that the numbers are right side up. So I guess the problem is the op amp or something after the pcm stage? My quick fix is working fine for now but I’m hoping to figure something better because I would love to be able to use the stereo outs.
    Hope this helps somebody with this problem sometime in the future.

  • Hi there does anyone out there know what value pots and limiting resistor values to use with the LTC1799 oscillator and the hr16s clock? I need to buy in some bits for this mod and anyone with previous experience of this mod that can share pearls of wisdom would be great.

    Also i have had a sporadic error message on one of my Hr16s Software Error 1 in conjunction with some erratic behavior.Mostly the machine operates perfectly but it seems to have an occasional meltdown? This machine has no bends attached as yet only a 5v and ground line for led circuit

  • Ok so i went ahead and got some bits and had a play with values and found that a 100k pot does the job just fine.One issue is that i have set up a switch to swap between original clock and LTC clock and it really hates being toggled while running.

    I guess this is because the switch has a break before make action and leaves the drum machine with no clock source connected for a millisecond as it is switched. Has anyone had more success in this regard? Perhaps with a make before break type switch?
    any ideas appreciated

  • Hmm… I haven’t tried a clock mod on the HR-16 yet. What does the machine do when you switch the clock? I’ll have to think about this one, there is probably a better way of switching the clocks using digital logic.

    The HR-16 giving you a software error- what version OS is it running? Have you tried running the self test?

  • When the toggle switch is flipped from original ceramic resonator to ltc1799 whilst on and playing a pattern the machine crashes nastily with a harsh noise and the display turns to gibberish. I have the original clock and the ltc1799 wired to a double throw switch with the clock input wired to the center pole. It is an on on type switch.

    Yes i have run the self test on the machine and all appears to be well it is a weird one really as it happened once or twice went really mad and started playing pattern 00 normally then instead if looping after 16 beats just carries on counting upwards!

    Whilst doing this it appeared to play lots of random snippets of various patterns stored all while supposedly playing pattern 00.. Seriously strange.. Now the machine appears to be absolutely fine after a few of these episodes.perhaps a small short? who knows? Would be great if anyone has a list of error codes as i cannot see them in the service manual?

    I love these machines but just when you think you know where you are with them and their quirks something really weird happens..

  • oh i forgot to mention that the machine with the error code is running version 1.09 a standard grey HR 16..

  • There might be a way to intercept the system clock in a way that doesn’t affect the cpu, only the sample playback. Downstream of the cpu, not directly at the crystal. I’ve done this with the TR-505, but i don’t know if it can be done with the HRs.

    I’m thinking of a way to switch the clocks with logic gates- a couple AND gates and a flip-flop should do it, i’ll see if i can draw something up…

    Yeah, these machines are great, but they have more bugs than a bait shop. If the pattern data is messed up, that points to a faulty SRAM. Either that, or some bad data was written to it. Did you try re-initializing? (back up your patterns first, they will be deleted.)

  • Yes I have achieved altering the clock for the samples without affecting the system speed with a Casio Rz1. It works really well and is much more useful in my opinion. It would be fantastic if we could find a work around for the samples only.

    Well the machine has behaved perfectly for some weeks now. I ran the self test since the errors occured too which re initialises the system I believe as well.

    Perhaps the error was caused by something as simple as a tiny short somewhere on the board which has been dislodged?

  • So would looking for cutting the clock further downstream be the way to go? I have read somewhere that pin 37 on the ASIC is the way to go.. I will have a tentative play and see what happens.

  • Checked the service manual and Pin 37 is the one.. Will test this out.

  • Yep that works nicely! solved the nasty crashing too! there is a really handy track that you can cut. Solder the new clock input from your switch to pin 37 and take the original clock from a handy solder blob on the trace on the other side of the cut..

  • Great job, Will! I’ll have to add that mod to this page. I’m sure it sounds awesome with the bends. (I also need to add a new distortion mod i found…)

  • Distortion mod eh… Sounds interesting?? I will post a vid of my design and mods when i can get hold of a decent camera. My Good friend has modded a micro milling machine for cnc and we have been experimenting with punching out some precision fascia panels for the controls. I have gone for a rotary switch array with each rotary patchable via an 8 port bay, indicator leds for each switch etc… all mounted on a nice brushed aluminum fascia plate. The distortion mod sounds interesting.. keep us posted havn’t found that one… The clock pitch mod is really great for expressive tuning up and down switching between clocks whilst in full swing.. highly recommended.. thanks to all the dedicated people on the forum sharing the love.and big huge thanks to you Justin for all your dedication to helping folks create fantastic machines and eccentric sounds! legendary!

  • I am working on an hr16 b as well at the moment and am not sure how i can cut the clock to the asic as the board is laminated over all the traces.. a real pain .. any ideas? if i scratch away the surface gently will i reveal the trace? Havn’t encountered boards like these before. Any ideas how deeply the traces are sealed?

  • You mean the green solder mask? It’s not that thick, you should be able to scrape it away easily.

    Can’t wait to see your finished machine! Be sure to send links. You’re lucky you have access to a CNC.

    The distortion mod involves messing with the gain resistors of the amp, i think. I’ve found at least 3 “flavors” of distortion there. I use a pot to control the amount. I’ll check my notes and post that info soon..

  • I mean that the board is such that you cannot see any of the traces at all.I am familiar with scratching back to copper and soldering to traces etc but it seems to have a layer of laminate over the entire surface of the board.. I read somewhere in the service manual about a four layer board?? is this what i am dealing with. have you seen a similar board? There are quite a few revisions of the boards that I have come across and even a totally different layout altogether exists on a much larger board.. I have one like this too and it similarly has the traces hidden?

    Yea the cnc mill is something that my friend put together. Bought a micro mill and added steppers to the axis and a control board links up to a computer. lots of fun but not quite up to full speed yet.. has been great for pressing out the holes on the fascia. he has been playing with milling text and logos into billets of aluminum.

  • ok so being a 4 layer board is really really irritating. the surface layer is a ground layer and the signal layer I need to get to to cut the clock trace is sandwiched underneath. cant really see a solution as yet.. very annoying.dont really fancy carving into the board on the chance it works.. even the service manual curses this 4 layer board revision.

  • Hmm, that’s unfortunate. We don’t want to mess with the ASIC. Maybe there’s another point somewhere… I’ll have to probe my HR-16B board… What board revision do you have, CA?

  • Yep its the CA revision… i will have a poke about with the multimeter and try to locate the clock input nearby.. not hopeful though as there really are no tracks that can be cut.. perhaps i could just wire the oscillators output to pin 37 and instead of cutting any tracks for switching i could put a switch on the ltc1799s power to to switch it on and off. not sure if this would really work but perhaps worth a try?

  • Worth a try. But be careful with the DM3AG. I just checked the handful of boards i have, i don’t have any CA, just A and AQ. The AQ has a sticker that says “rev B1.” Yeah, i would see if any other points connect to pin 37.

  • Will report any useful findings. I have an AQ revision board here too waiting to be modded in the future. Hope that one is less troublesome!

  • Ok so after much poking around with the continuity tester I located all I needed to get the clock input to the ASIC on the CA revision board.

    Its quite a fiddly job to find the point to cut though . I will try and describe the process…

    If you flip the board onto its back with all the solder joints facing you locate pin 37 of the ASIC (the manual has pin arrangements listed). Once you have found it visually count four pins to the right and then scan down at a right angle towards the bottom edge of the board until you locate a solder through hole with no component soldered.

    Get out your multimeter and set to continuity buzzer and check for connection between here and pin 37. Once you have confirmed continuity hold up the board in front of a bright lamp. Look at the hole closely and you should be able to make out a thin track buried in the board in the tiny translucent area around it that is not covered by the outer ground layer.

    This is your micro window into cutting that clock input source and adding a switch for the ltc clock. Very carefully with a sharp scalpel cut down into the board just enough to break the track. Check continuity to confirm that the cut has been successful.

    Now we need to locate a point farther back so that we can re connect this point with a double throw switch to toggle between the ltc and the original clock.

    Turn the board back over and look for the small horizontally orientated chip just below the large 8031. It is labelled 74HC04N and pin 5 on this baby should give you the point to solder to…

    Check everything thoroughly with that multimeter before firing it up…

    Really hope this tutorial helps someone out there as It is really frustrating to discover that things are a bit more tricky to achieve with this four layer board..

    Happy soldering!!

  • Hello,
    I am about to get an HR-16 from a classified ad for dirt cheap and am wondering if I can circuit bend on the fly (with a paperclip like the youtube video on the SR-16) without electrocuting myself. In other words a way without soldering.

  • Yeah, it’s as easy as it looks in that video! And I can’t say it’s impossible to electrocute yourself, but you would really have to try hard to harm yourself. You need to worry more about harming the HR16. Just stick to the 2 sound chips

  • Right so i finally got around to getting some shots of my HR-16 design.

    circuit bent alesis hr 16

    circuit bent alesis hr 16

    Hope you guys like… :)

  • vid to come soon

  • Ok so Here is the vid too.. just a couple of variations of the same pattern looping and me just having a bit of a random play..

    The Alesis HR 16 -K by Kymatica from Kymatica on Vimeo.

    thanks for checking it out ..

  • Ooooh, pretty! Looks nice and clean, great job!

  • oops the first image was the blurry one this should be a bit sharper..

  • Hello,
    I recently bought a hr16 version 1.04 and it didn’t saved the beats once i turned it off. when i turn it on within a few minutes there was nothning and al the voices i changed turned back to what it was in the beginnning. I only replaced the battery with a new one but i still have the same problem!? i also have a permanently bended hr16B with a 2.0 version chips that has sounds when i turn it on.. what must i do to make the HR16 save my beats? and can i change the chips from the 16B with the ones in the 16? can someone help me please?

  • Sounds like you need to replace the SRAM. And yes, you can swap the OS and sample chips between the two machines.

  • Thanks, do you know if it’s possible to swap the sram of the 16 B with the one in the 16? ordering is kind of difficult for me as i am from the netherlands..

  • Hello again, I’ve tried to remove the ic’s but there is not any movement in them,
    how do i remove them? sorry for my questions.. but i’m new to this. never bended or repaired a drumcomputer, this is my first time. : ) I’m really liking the things i see here especially the white HR is very cool! Thanks Again!
    Hope you can answer me.

    and if all fails (i checked the link yesterday) i’m going to order the sram.

  • Albert- Yes, you can swap the SRAM between machines.

    Are the IC’s socketed? A previous commenter had problems replacing chips in his SR-16 because they were soldered directly to the board and not in sockets. Take a look at this photo:

    The chip circled in orange is in a socket, while the other chips are not. If your chips are soldered directly to the board, they will be very hard to remove without damaging something.

  • I’ve removed them, they were in sockets, and replaced them with the other srams that were working in the HR16B but my problem remains… still no memory.. i’ve read the service manual but am not getting any wiser..i’ve also have run the self test and it says that everything is ok. also lifted R41.. why can’t i save any beats? do or can i change the 8031 of the 16 B with the 16? does that help?

  • No memory means either the SRAM and/or the battery is dead. Are you sure the battery is good? If the machine hasn’t been serviced in 10 years, the batt is probably dead.

    Does the HR forget patterns only when you unplug the power, or even when it’s still on? If it’s only when you unplug power, thats the battery. If it forgets when the machine is still on, that’s the SRAM.

  • I’ve got It working!!! : ) and I’m Happy!!! the battery i bought new was not full so i got another and it works!! I’m So HAppy!! Thanks For All Your Feedback!!
    i’kll be back when i start bending : )



  • I have an HR-16 & when I turn it on the orange LCD lights up, the top line is just solid blocks, the line below – nothing. The red light above the play button is on but nothing happens if I push any of the other buttons – no other lights go on, the LCD stays the same & no sound from the pads or when I press play – nothing happens. Any idea what I can do or is it beyond repair? Any help would be greatly appreciated – many thanks – Doug

  • [...] The incredible wealth of information about bending it, available at burnkit2600.com. [...]

  • First off, thank you so much to Justin and everyone who’s contributed here, this collection of information has taught me a lot about circuit bending, which I’ve always had an interest in and only now have explored with any depth. I just finished a HR-16 bend heavily inspired by your work here, and posted a long article detailing my process. Thought I’d share it, as I did as I included a lot of photos at different stages and described my various unexpected obstacles and solutions. Hope you find it interesting/helpful!


  • By the way, I was able to use the DECRYPT program you wrote to decode the Quadraverb OS as well! I have to split the 64k OS chip file into two 32k chunks (seems to need 8.3 filenames as well) and did them, then recombined.

  • Interesting! Let us know if you find any easter eggs. :)

  • Jesse Smith recently posted his hr16b eprom generator software. It burns 3 chips, one OS and two sound roms. It allows for custom sample lengths and names.. Booyakasha. http://thegzp.com/stoi2m1/2012/03/09/hr-16-info-manuals-sysex-dumps-soundbanks-firmware-and-editor/

  • Hello,

    i’ve just “mod” my HR-16 with piggyback EPROMS for both U15 and U16. The original HR-16 EPROM is at bottom and HR-16B EPROM is at top. I can select with 2 switchs which EPROMs is played by chip select signals (U15 original A, U15 B version, U16 original A, U16 B version). All works fines except that some HR-16 samples are cutted with click noises. I have put HR-16B OS V2.00 and I know that OS contains samples names and also samples start and length infos.
    My question : is it possible by modifying OS HR-16B V2.00 to be compatible both with HR-16 and HR-16B samples EPROMs ?
    Where are located samples starts and length in OS binary ?

  • You could piggyback the OS roms as well, but you would have to turn the machine off when you switch between them.

  • In regards to modifying the HR-16/B clock using an LTC1799 which is the better option and what is the difference between altering the clock point at pin 37 of the ASIC chip in comparison to altering the clock point/s at pin/s 18/19 of the 80C31 MPU chip?

  • I just spend a bit of time doing the reverse — unscrambling the sample ROM data into clean 24 bit samples. I only did the HR16 and not the HR16B data. Code and unscrambled samples here: http://jens.org/stuff/HR16.rar

    Here is the code (perl) that did the unscrambling in case anyone is interested in having a look at just for reference: http://jens.org/stuff/decode_hr.txt

    Funnily enough I quickly realized the dynamic range of the samples is beyond just 16 bits, even though the machine is called “HR-16″.

    Not sure if this all is 100% correct. Questions or feedback, mail jens@panix.com .

  • Hi justin , hi guys
    I’m working on an hr-16 bending , i bought to you the upgrade os from the hr-b :)
    I understand and really like your multi switch system , i used one on my sk-1 but it’s a really good idea to combine two switches !!

    There’s just one thing that i don’t understand , it’s your led light system ? Do you have a picture of it ?
    Can you help me about the way to wired the led ? To have a continuous illumination just depending of the switch

    Thank u very much for ur help

  • Romain- I used DP6T switches- That means you have 2 center poles and 6 “throws” or outside positions for each pole. For bends- One pole connects to the pole from another DP6T, and all those 12 throws connect to points on the sound ROMs. This gives you 6 points that can connect to 6 other points. I also wired up toggles that make or break the connection between 2 DP6Ts. Another way to turn bends off would be to leave one of the 6 positions empty.

    For the LEDs- Use the 2nd pole of the DP6T. LEDs are separate from the bends. Having 2 poles is like having 2 switches in one. The pole can connect to 5V (all the ICs are powered by 5V) The + lead of the LEDs connect to the 6 throws, their other leads connect to ground. You may need to use current limiting resistors on the LEDs if necessary, i think the LEDs i used did not need resistors. If this is confusing, i can post a video eventually.

  • Thank u very much for ur explanation ,
    Actually it works i almost finished my bended hr 16 i droped led system not due to led system ( i understood that ) but due to the dificulty of drilling perfectly straight 6 leds with 0,5 mm between each ;)

    I’ll post a picture of my finished machine as soon as she ‘s done
    Thanks again for ur help

  • Do you guys have any experience with differences between the original HR-16 circuit and the “rev B1″ HR-16′s that I believe were made from 1988 onwards? I’ve got an original HR (the one from 1987 where there’s no big exposed inductor and there are two additional heat sinks) and that one can have as many bends connected as you can find patch cables, and it’s never crashed, ever. Now I just got my hands on a “rev B1″ HR that has the inductor and only one heat sink – seems a lot cheeper – and for some reason whenever I start connecting two or more bends, the machine crashes! Sometimes it’ll even crash from having just one bend connected, but there’s no regularity to it; the crashes happen sometimes, but not other times, with the same bends. It seems to all depend on the will of the EPROM gods. Of course, when no bends are connected, the HR works just fine. I was wondering, has anyone else has experienced this kind of inconsistency when bending an HR?

  • Yes. I don’t remember the details off the top of my head, but that issue is covered in the service manual. Something about the power reset circuit. The manual mentions that people were having issues when the HR was on the same circuit as night club lights, it would reset if there were power fluctuations. I think it’s just a matter of replacing a component or two, check our manuals section: burnkit2600.com/manuals

  • Thanks so much for that pointer. The problem was that my living room wall outlet is shafty and is always fluctuating in voltage, and the bends made the circuit just unstable enough that the machine kept doing a power reset. All I had to do was change R28 from 3k to 1.5k and now it’s working brilliantly.

  • Great! And thanks for following up with your results. I’ll add this to the FAQ that I am putting together.

  • Hi guys!

    I bought a refurbished HR-16.
    I used the power of the mmt-8 the seller sold me with and got no sound.
    And after a day or two,it put me an “software error number 2″.
    A friend changed the power and now i have the sounds but after touching patt button i still have the error!
    What should i do?


  • Ok,never mind,i didn’t push the record,erase,delete hard enough…

  • Ah, good! If your buttons are wearing out, they can be refurbished by using conductive paint.

  • I’ll get back to you on that lol

  • I was wondering if anyone has ever come across with an HR-16B that turns on but won’t output any sound to a speaker? It turns and I start recording but no sounds comes out. I’ve switched my cables around and I know the speaker works I’m using a 500ma trisonic universal adapter on 110v input and 9v output

    I have another hr-16b that doesnt have this problem but this one does. Is a connection maybe out? I just wanted to see if anyone had a similar experience and see if I can save me some more guessing but don’t bother if you don’t want to help. I don’t want to frustrate anybody. Thank you though for this site and for all doing a great job thank you so much.

  • thanks for everyone’s notes and goodwill on these projects!

    Any word on those distortion mods you mentioned back on Mar 17, 2011?
    *dying for infos!

    Thanks tons in advance!

  • I was considering not bending my new HR just because I didn’t want to kill it, but this site has completely changed my mind. I’ll give it a shot after I master the machine un-bent. I am also curious about that distortion mod, and I hope this comment section isn’t dead because I thoroughly enjoyed reading it. And I’m going to need someone to help with all the problems I run into! :P Warm regards from Ohio.

  • has anyone figured out a way to clean the plastic finger pads? Mine are a bit yellow, I was wondering perhaps a bit of bleach/hydrogen peroxide?

  • I wanted to bring something to the group as I have many questions I want to ask myself, so here are some of my findings.

    I managed to get a pretty decent emulation of the HR and SR compiled and running in MAME/MESS (An Arcade game emulation system) it emulates the whole machine pretty well and includes drivers for the LCD panel so that any output that would have been on the drum machine is displayed on your computer screen.
    I’m hoping some of you will find this useful, I have been using it to test out my eprom images before I get to burning them with good results.
    You can also load/save via casette interface (by loading in wav files into mame)

    I have made a pre-buit installation for you http://muzikliberated.com/alesis.zip

    Key Mappings for Alesis HR-16/HR-16B/SR-16 Drum Machines
    File Created by Brad Holland
    August 20 2013

    ** HR-16 / HR-16B **

    + RIGHT

    COPY C
    PATT P
    SONG S
    TAPE Y
    FILL F

    1 1
    2 2
    3 3
    4 4
    5 5
    6 6
    7 7
    8 8
    9 9
    0 0

    TUNE H
    MIX M

    KICK 1_PAD
    PERC 3 7_PAD
    PERC 4 8_PAD
    TOM 1 F1
    TOM 2 F2
    TOM 3 F3
    TOM 4 F4
    RIDE F5
    CRASH F6
    PERC 1 F7
    PERC 2 F8

    SELECT FADER Cursor Up / Cursor Down

    ** SR-16 **

    1 1
    2 2
    3 3
    4 4
    5 5
    6 6
    7 7
    8 8
    9 9
    0 0
    UP UP
    A A
    B B
    FILL F
    COPY C

    KICK F1
    SNARE F2
    CLAPS F5
    PERC 2 F6
    TOM 1 1_PAD
    TOM 2 2_PAD
    TOM 3 3_PAD
    RIDE 4_PAD
    PERC 1 6_PAD

  • Wow that sounds amazing! I wonder if you can emulate all the circuit bends to the sample ROMs as well?

  • Hi Justin,
    i hope you can help me.
    The Problem:
    my hr 16 sounds, but the Dataslider and the led’s not in Fuction.
    Any Idea to fix that Prob’ ?

    Best regards,


  • Hi Justin,

    i clean the complete unit and check the wires….and now it runs!

  • hello, im new to cb machines and im just experimenting with the hr-16, i hate those pads so im taking them out and building a new enclosure for the rest of the guts and leaving it with the midi and audio i/o’s, all i would need to do is not connect the cable that runs to the pads, correct? or is it more involved than that? i love the sound of this thing but those pads are so horrible.

  • yeah, same problem here. the pads sound terrible. when I power down my machine and press on them I really don’t get a good tone.

  • Hi,

    I have the following problem with my HR-16: when I plug two audio cables into Out 1 left and right outputs, I only have sound on the left output, no sound on right output. When I unplug the left cable, then I get sound on the right output. When I only plug the left cable, I have the same sound as when I plug both the audio cables. Out 2 works as expected, I have sound on both the left and right output in stereo. Off course, I have checked the MIX panning options, and the global and individual pad volume levels. Should be an easy one for HR-16 guru’s :-)

    Thanks for your help.

  • I broke the shaft off of the volume slider when trying to remove the cap.
    Does anybody know the value of the pot or a suitable replacement?

  • @Bernard- If you are certain the mix settings are correct, there may be a bad solder connection or a short on the output jacks.

  • @eric – I measure it at 20K, and it’s a stereo pot

  • @Justin- The problem was a faulty volume pot. The right channel was broken. Moreover, it was not the original pot. This one was 50K pot, and the wiring was wrong too. Well, I replaced it with a new stereo exp. 10K pot and everything is working perfectly now. (a linear 20K pot could have been better, though) – Thanks for you reply.

  • Top two of the burn it yourself ROMS are no longer available!!

    Please repost them


  • Hi

    I have used this website multiple times in the past to help me get to where I have with bending the HR16 but am having problems regarding the pitch bend mod. I unfortunately have the revision of board that has the laminate over all the tracks so following the standard tutorial does not work. I have read through the reply from ‘Will’ regarding this type of board and although it helps I am slightly lost.

    I have found the solder-through point that is explained that connects to pin 37 of the ASIC chip and holding it up to the light I can just about see the start of the track coming off the top of that point. My questions are….

    Once I cut that track how do I wire up the new LTC1799 that I have bought from circuitbenders.co.uk? Do I connect the ‘out’ of that timer directly to pin 37 of the ASIC chip?

    How about if I wish to toggle between the new timer and the in-built timer? Do I connect one side of the switch to the ‘out’ of the LTC1799 and 1 side to pin 5 of the 74HC04N chip mentioned by Will with the centre pin of the switch going to pin 37 of the ASIC?

    Lastly pin 5 of the 74HC04N does not show continuity to pin 37 of the ASIC chip, should it?

    I have not gone ahead and done any cutting of tracks etc yet as worried I am going to screw this up…

    Any help from anyone regarding this more tricky board revision would be appreciated.

  • Planning a patchbay for my sr16 and correct me if I’m wrong but the pin layout for the sound roms is the same for the hr16, in other words the pins to avoid and addresses and what not are the same, correct? Not alot of technical data on the net to be found about the sr16 well not as much as the hr16.

  • Hello everyone!
    I’ve troubles with my hr-16…
    The sound is really too low, any suggestion?


  • I just found a HR16 on a road trip, and was super stoked to get it home and run it.

    I opened it up to just check things out (before starting it up) and OMG!!!!

    The back up batt. EXPLODED in the unit (I don’t know when, some time back I’d imagine).

    I am wondering, is this unit at ALL salvageable? If I spend some time cleaning up ALL the mess inside, clean ALL the board where it leaked on to and is bridging circuits etc.? Is this a common issue with these? Are the chips DONE???


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