Here’s the documentation he sent me:

rom switcher (like yours) being removed; (soldered the U24 points to the underside of it)

testing out the U24 bends, machine was all garbled, display whacked out, all 25 points were grounding out, id seen conductive paint before but its been silver, the shit sprayed inside here is brown/gray. lucky the roms+pcb are/were all ok. re-stalled everything and fixed some shit id busted along the way.

its a bit tighter in there now with more NON-rainbow ribbon cable folding in on itself.

she come good after those resets. rub a dubbin dirty gutter glitch cut above the rest;

and when you take those U40 bends straight to ouput; the dirty rasta skankyness never known before spews filthy glitch covered rainbow ribbon garble noises.. the core of every good sound excursion. thanks josh.

From what I remember, you have to disassemble the entire machine to get at the button board. The RX5 isn’t as easy to take apart as other drum machines.  I don’t recall the whole process so that part is up to you, but here’s a picture of the disassembled unit:

On the far right you can see the PCB with the button contacts that needs to be cleaned. All you need to do is remove the plastic sheet that’s taped to the PCB, then give the contacts a good cleaning. You’ll probably want to clean both the PCB contacts and the contacts on the plastic sheet. I did this job back in the days before I discovered DeoxIT, so I used 91% isopropyl alcohol instead. It did the trick just fine.

If your buttons are sticky, then you’ll also have to remove them from the board for cleaning. The picture above shows the button board (second from right). From the rear of the board, you’ll see 4 small tabs that lock each button into place. You can just bend these tabs inward to remove the button. They’re spring loaded, so be careful not to lose any of the parts inside the button. I had to clean a bunch of grime off the edges of the buttons as well as the rectangular slots of the button board frame. I used warm soapy water. Now your buttons will work like new.

Here’s a demo of the Gumi-bent Yamaha RX5. This machine is especially good for bending thanks to all of the voice editing functions. This is just the stereo mix from the main outs. Learn how to bend your RX5 here.

The finished circuit bent RX5 with 36 point SPDT patchbay.

Yamaha RX5 Schematic

Here’s a quick demo:

Bob Click’s Fantastic Light Parade

I owe a big thanks to my good friend Mike S. for this. He gave me this RX5 when I moved away ten years ago. Thanks duder, everything works now.

So the first step is to identify which ROM pins are “safe” for connection to one another. This usually means at least avoiding the power pins. A look at the schematic shows us which pins do what. I only wired the address and data pins. So far I’ve had no issues (i.e. crashing the machine), but do this at your own risk. I’ve played it pretty safe here, so if you’ve had luck using any of the other pins let us know.

Schematic showing which ROM pins do what. We'll be wiring the pins marked in blue.

Here's the view of the ROM on the PCB. There are two ROMs (IC45 & 46), but they share the same connections, so you can use whichever IC you want. Connect the dots...

I usually solder my wires to the bottom of the PCB, but in this case it made more sense to use the top of the IC due to the way the RX5 is assembled.

Rainbow wire soldered to the ROM. The wires run to an enclosure on the RX5's top panel, which houses the SPDT patch bay.

And here’s the completed RX5. I went with a SPDT switch patchbay for live use, but of course the design of your bending interface is up to you. A DB25 port and a handful of banana jacks might be handy. The next step is to install mute switches for each voice.

The finished circuit bent RX5 with 36 point SPDT patchbay. Oh, and that switch by the Accent 2 button is just a latch (for Accent 2).

PARTS & TOOLS:

• - piezoelectric transducer element (RadioShack #273-073A is used here)
• - female mono jack (panel mount RadioShack #274-252 or cable mount RadioShack #274-340)
• - small diameter heat shrink tubing, about 5″ long (optional)
• - self mixing epoxy with syringe (optional)
• - soldering iron/solder (not needed if you use a non-solder type mono jack)
• - miniature flat-head screw driver or similar tool
• - razor blade, wire cutters, or similar tool

The first step is to extract the piezo element from the plastic casing. It can be a little tricky opening the case because you have to be careful not to break the piezo element in the process. They are somewhat fragile. You can start by wedging a mini screwdriver into the space where the wires exit the case. Work the screwdriver around the edge of the case while prying upwards. There is usually about 1/8" vertical space between the back cover and the element, so you have some room for prying.

Eventually the back cover will loosen. Pull it off and discard.

Now you have to cut open the rest of the case in order to pull out the piezo element. Use a razor blade or sharp wire cutters to cut a line from the center of the plastic case to the edge. Make sure the plastic is cut all the way through. Once this is done, carefully twist the plastic case until the edges of the piezo element separate from the edge of the case. This might be the hardest part of the project, so use whatever extraction technique that works best for you.

Pull out the piezo element and recycle the plastic casing.

Next, break out a female 1/4" mono jack assembly. Before soldering the wires to the mono jack (upper left in photo), remember to slip the mono jack case (upper right) over the wires first, or else you'll have to resolder. You can also use a panel mount mono jack.

Panel mount mono jack.

Now solder the wires to the mono jack's solder tabs. The black wire goes to the sleeve (ground). The red wire goes to the tip (signal). With some mono jack assemblies it's hard to tell which tab is connected to the sleeve and which is connected to the tip. Use a multimeter to test continuity if you have one. If not, you'll have to experiment, but at least you have a 50/50 chance of getting it right first time. If you have no soldering iron, you can use a non-solder type mono jack assembly instead.

Now bend the strain relief tabs over one another and pinch them with a pliers to form a secure grip around the wires. Use an open flame or other heat source to shrink the entire length of the heat shrink tubing. Screw the mono jack into the mono jack case.

At this point your contact mic should look something like this. Test the mic by plugging it into a mixer. You'll probably have to turn the gain up pretty high. Tap the mic and you should hear the sound. If there is no sound, first make sure the mic is connected to the mixer properly. If you still get no sound, check the solder connections on the mono jack and resolder if necessary. Also make sure the bare red and black wires aren't touching one another or shorting out anywhere on the jack.

In order to make your contact mic more robust, apply a large dab of epoxy to the top of the element. This will prevent the piezo disc from damage and keep the wires from breaking off. Let the epoxy flow evenly to the edges of the element, but don't use so much that it flows over the edges. This process is easiest if you use a self-mixing epoxy syringe because you can apply the epoxy directly to the element while maintaining control of the flow. Allow the epoxy to dry and you're ready to begin recording and triggering.

As always, I may have made a couple of mistakes here. I wrote this up by memory and according to the voice board schematic. I’m a little unsure of the Clap components I’ve marked in the labeled schematic, but since it already has its own output you probably don’t need to worry about swapping it. If you spot any errors, please post here and I’ll make the corrections.

Swapping the voices is just a matter of re-routing the signal from one location on the voice board to another. I’ve found it’s easiest to just disconnect one side of the voice’s “last” resistor (before going into the voice group’s op-amp), solder a wire onto the free end of that resistor, then run the wire to the desired location on the PCB (into the new voice group’s op-amp).

Below is an example of swapping the Toms with the Clave. R38, R35, and R39 are the Toms and Tom Noise. De-solder the ends of the resistors (marked in red) and solder them to a wire. Then run this wire over to the empty hole of R106, which will be de-soldered in the next step.

Now de-solder the end of R106 (marked in green) and solder it to a wire. Then run the other end of this wire to one of the empty Tom locations (R38, R35, or R39).

The Toms and Clave voices are now swapped. The Toms are now on the Cowbell output and the Clave is now on the Snare Drum output. When you adjust the associated voice group level pot, the volume of the voices will change accordingly.

If you want to swap other voices around the process is the same, you just use different components. Take a look at the labeled voice swapping Voice Board schematic. It shows all of the voice components and locations on the PCB needed for voice swapping.

Note that when you’re swapping voices, you’re also routing them to different op-amps (IC1 and IC5 in the above example). This will effect how the voice sounds slightly. You can experiment with changing the resistor and cap values of the op-amps to match the original tone of the voice.

I found this info in this circuitbenders thread. It was originally written in French. Here is my translation with help from Google Translator:

“To initialize the parameters only: hold down the [ERASE] button while you turn on the power. To clear the pattern/song data: penny voltage device, hold down the No. 1 button and press [ERASE], then [ENTER] twice.” (I have no idea what “penny voltage device” means, but it’s the same procedure as listed on p.21 of the Owner’s Manual)

Note that these procedures will reset all of your custom settings and erase all of your patterns.

I performed both of these procedures on my R-100 and now it’s 100% functional again. The machine became rather confused after I tried installing a global pitch mod and mucked around with the 16MHz xtal. The sequencer was locking up and the display was showing crazy characters and pattern parameters. This solved the problem.

My TR-707 had a broken slide pot for the Mid Tom. It wouldn’t change the tom’s volume and the voice was very loud and a little distorted from both the main and individual outputs. When I tested the pot with my meter, I got a sporadic reading of several hundred k anywhere in the slider’s travel. When I removed the pot from the board, I noticed that the slider’s shaft was a little loose in its track (i.e. I could wiggle it up and down slightly).  Then I noticed I could get the normal resistance range (0R to about 40k) if I pressed down on the slider’s shaft while moving it. To fix the problem, all I had to do was lightly pinch the tabs of the slider’s case, which reseated the slider snug into its track. Now it works like new. Here’s a quick how to:

1) Remove the offending slide pot from the PCB.

2) Test the resistance with a meter, sliding the shaft as you normally would. If you get seemingly random readings, this might mean the shaft is loose in its track.

3) Try pressing downward on the slider’s shaft while moving it and test the resistance range. It should go from 0R to around 40k (or at least that’s the range of all the sliders I tested on my 707). If so, this fix will probably work for you. If not, the problem might be someplace else, though you can try cleaning the contacts with DeoxIT, which might help.

4) Look at the rear of the slider’s case and note the four tabs holding it together (marked in orange below):

5) Lightly pinch these tabs into the case using a needle-nose pliers or similar tool. Be careful not to pinch too hard. If you do the slider can become stiff/sticky at the top and bottom of its travel. If that happens you can just pry the tabs outward again and start over. You can try just pinching each tab a little at time until you get smooth action and solid resistance readings:

6) It wouldn’t hurt to clean the slider with DeoxIT as long as you’re here, eh?

7) Once the slider is tested and functioning normally, solder it back into the PCB. That’s it.