Roland U-20 Synthesizer Key Contact Repair

Roland U-20 RS/PCM Synthesizer

Yesterday, I was given a Roland U-20 by one of the sales clerks at a local Hard Off store here in Japan. Only one key was working and rather than just selling it as junk, he decided to just throw into the bag along with my guitar strings that I purchased…laugh. I told the guy that it was a very common problem with the Roland U-20 that the keys were bad so perhaps I might be able to find more info and try to fix it. He said “Good Luck” and I was off on another project. With the success a day earlier with the Yamaha SY77 in my previous post, I was looking forward to the Roland U-20 challenge. This article talks about some things that did not work and some repair methods that worked 100% in fixing the key issue. Below are some points to remember about the Roland U-20 problems.

1. The Roland U-20 is a easy, but time consuming to take apart. You pretty much have to unscrew everything and move the PCB boards out of the way in order to get the keys out of the U-20. It’s very simple to do, but a pain to have to remove everything. I actually just removed the screws and shifted them around to make clearance so that I could slide the key assembly around. The components, especially the ribbon cables are delicate so be careful and take your time.

2. There is a flimsy ribbon cable attached to the key assembly ( see photo below ) which I did not remove. I’ve heard one shouldn’t remove this cable because it “could” result in the removal of some of the traces. If that happens, it’s easy to repair, but I found that I didn’t need to remove the cable. Instead I removed the key assembly and while balancing it in one hand, I reached over and placed the metal bottom cover back on. I then carefully placed the key assembly on a work towel on top. The ribbon cable is just long enough to rest the keys on the bottom of the synth to work from. The reason for doing this was so that I could test each key with the power on when ready. There was NO WAY I was going to put all this back together only to find out one key didn’t work. The keys were going to work perfectly before I reassembled the U-20 and so it was paramount that I could test the keys during my repair. Resting the key assembly on the bottom of the synth meant I could cover the PSU and not worry about bumping any of the other components during the repair process. I worked with the power off until I was ready to test the Silicon rubber contacts.

Ribbon Cable Roland U-20

3. The Roland U-20 also has the dreadful red epoxy problem. You can see in the photo that the epoxy is already starting to break down. Usually I soak and wash the keys in a special solution that removes the red epoxy. This can take several days, so for a quick fix that works well, I simply apply some rubber goop cement that actually acts as a sealant to prevent the red epoxy from escaping. Since the epoxy is at it’s earliest stages of breaking down, I found the quick fix to be enough to cure the problem. Now if the weights were falling off and the keys were sticking together, I of course would opt for the full cleaning workout.

Red Epoxy Roland U-20

4. The Roland U-20 suffers from the reduction and/or obstruction of the carbon Conductive contacts/prints on the PCB board and Silicone Rubber pieces. In the photo below, I used a product called Caikote 44 which allowed me to apply a thin Conductive Silver/Carbon Coating over both the Silicone Rubber contact AND the carbon print contacts on the PCB board. IMPORTANT!!! In the photo you will notice I did a rather messy job of applying the conductive coating onto the PCB board carbon prints. This is WRONG! I had a “DUH” moment and realized that you MUST apply the conductive coating on each individual carbon contact without touching the others. I later went back with some alcohol solution and removed the excess in between the contacts. Each key has 3 or 4 individual carbon prints to coat.

Some people just clean these with alcohol cleaner and put the key assembly back together. I find this didn’t work at all for me and I felt it was a bit unreliable as well or at least could be. Instead I found with past experience that on the Korg PolySix, Caikote 44 was THE BEST solution for cleaning this annoying problem without ever having to think about it again. This is laughingly why I caked the stuff on the first time because boy it works wonders. My Polysix has been playing beautifully ever since I slapped that Conductive Silver/Carbon Coating on it. I can tell you it works awesome for the Roland U-20 as well. Note, you may need to use a toothpick or something thin in order to apply effectively. When I tested the keys with the slop job I did above, none of the keys worked. I then knew I was suppose to apply the Conductive Silver/Carbon Coating to each contact individually. This makes sense and I don’t know why I did it the messy way…laugh. Actually I’m being hard on myself in that I really wasn’t sure, so I suppose I now have the experience of knowing otherwise.

Conductive Silver/Carbon Coating Caikote 44 Roland U-20

After putting the Roland U-20 back together, everything works perfectly. It simply sounds great and all of the keys work 100% as they should. I can also rest assured that with the application of the Conductive Silver/Carbon Coating, I won’t be waking up on a cold morning to discover one key is now dead. It should continue working “hopefully” for years to come. I will say again though as I’ve said it in past articles. You really need to keep playing these synthesizers to keep them in shape. Letting them sit for years on end will not keep them in good “working” condition. They need to be played, especially synths with key issues.

The Roland U-20 is a fun little synth. It has some great sounds on board that don’t seem to exist in later Roland models such as the JV-1080. Some of the Roland U-20 sounds are pretty unique. Furthermore, the U-20 has TWO programmable chord memory buttons instead of one that many other synths have. This allows for some creative playing which I enjoy. There is also an arpeggiator that can also be applied to the chord memories. Plus there are a couple of assignable slider controls. The U-20 has six parts and an additional rhythm part for external sequencing. There is a transpose button, joystick with modulation, and jump button for easier editing of sounds. It’s about the size of a Nord Lead and it’s very light weight. The keys actually feel pretty good once you have them in shape. Mine don’t clack or trip my fingers up at all. There are some classic sounds on board and the effects sound wonderful too. Yes it’s old, dated, and limited a little bit, but it definitely has a bundle of character. Yes, it’s a rompler but the kind I don’t mind having at all. It will do the job just fine.

Yamaha SY-77 No Sound Output Solved – Battery Check!

Yamaha SY-77 Synthesizer

Sitting in a store right down the street here in Japan were two Yamaha SY77 synths that were for $10 and $30 respectively. Both were in minty condition and had a note on them that said “No Sound”. The note confirmed that both would power on but had no sound coming out of the outputs. It seemed the problem could be a bad output board, except it still was possible the batteries might needed to be changed in these. I decided to wait until I could come up with some additional space. Both had been in the store for several months which lead me to believe that they could have some major issues. I waited and pondered whether I should gamble or not with these synths.

Well it wasn’t long and I got the itch to take on another project so I went back and bought one of the Yamaha SY77’s in the store with no output. I bought the $30 one because it came with a case, no chipped keys and overall looked in near mint condition. The other $10 one had a chipped key and no case, but it also was in excellent condition. When I got home I found inside the case had the manuals and an MDC64 memory card. I thought if I couldn’t get the SY77 working, at least I’d score on the memory card. I powered it up and sure enough no sound, BUT, I got a delightful message saying the battery needed to be changed. With my past experience at these stores in Japan, the sales clerks most of the time call that “broken” or “junk”. I had suspected that could be the problem because with my first SY77 I had to change the battery and had all sorts of issues which weren’t resolved until that was done. I also took a look at the bottom of the SY77 and clearly it had never been opened. To me this is often a sign that any sort of problem “could” in fact be battery related.

Thus I changed the battery and did the reset procedure. Presto! The Yamaha SY77 came back to life and check out with flying colors. I then threw a disk into the floppy drive to have a laugh because in almost every case they are broken with bad belts. To my surprise, the floppy disk drive worked without a hitch. I was able to format and save data to the floppy. I probably shouldn’t be surprised in that the inside was absolutely spotless with no dust and almost like new. There were a few label stickers on the outside which suggested the SY77 was used in a studio and likely not stored under the house…laugh.

As a result, case closed. The Yamaha SY77 is working great. I suspect the other one at the shop is the same, although I simply don’t have storage to bring in another tank such as the SY77. It’s a great synth but they are big and heavy. I’m sure another tech will snag it sometime.

With my two SY77 synths I can say that the batteries were the root of all issues including the lack of audio output. The battery is soldered in there and my holders don’t fit, so I usually have to solder in custom wiring. If anyone has troubles with their Yamaha SY77, be sure to check the battery and replace it properly. After resetting, you shouldn’t have any further issues.

Last night I played the SY77 for about an hour with some custom patches. It sure sounded wonderful!! It’s amazing how the SY77 was like 3 grand when they first came out.

Nice video here form Youtube: Yamaha SY77 Digital Synth Sounding Very Analog like

Roland Juno-2 Won’t Power On – Repair Adventures

Two Roland Alpha Juno-2 Synths

Hi everyone,

Recently I acquired my 3rd Roland Juno 2 synth for free because it simply wouldn’t turn on. The owner said it worked before putting it into storage, and then about a year later he turned it on and nothing happened. He gave it to me because he already had too many door stops…laugh. I thought maybe I could fix it, but it’s proven to be quite stubborn. Above is a photo of my work area where I’m currently testing the broken Juno-2 (bottom one) with a fully operational one above (top).

The Roland Juno-2 basically has never been opened. I open a lot of synths and I can tell that I’m the first one to crack it open. The Juno-2 is in excellent condition all around. When you flip the power switch it’s completely dead. No flicker, no heat, no noise, nothing. It’s like the power doesn’t even get to first base or even into the machine. I do try to repair my own synths, however I usually leave the Power supply area alone as that is not my strong point. Inside the Juno-2 seems pretty basic, so I thought I would scout around and see if I could find the problem in the hopes that it might be a simple fix.

I opened up the synth and inside everything seemed clean and connected. The power cable was fine, the switch looked good, along with everything else…BUT… the Electrolytic Capacitors looked funny to me on the Power Supply Board. Usually if they are bad I notice a bulging at the top, however the three capacitors on the power supply board look fine on top. The bottom however look like they could either be leaking or perhaps surrounded by a glue of sorts. I’m not sure which, although my guess it’s a leak. It’s kind of dull and crusty while glue is usually shiny and smooth.

My thoughts are that if the Electrolytic Capacitors are bad, that might be the reason the Juno-2 is not turning on, OR getting power to the rest of the synth from the Power Supply board. Otherwise, I have no idea why the Juno 2 will not power on.

Any ideas would be greatly appreciated.

Here are some photos.

Roland Juno-2 Electrolytic Capacitors

Roland Juno-2 Electrolytic Capacitors

Roland Juno-2 Electrolytic Capacitors

UPDATE #1:

I wrote a comment below about the switch looking bad. Here is a photo. The wires are loosely soldered to the two plugs attached to the switch. The two plugs wiggle. On my other working Juno-2, the switch, plugs, and wires are rock solid with zero play.

Roland Alpha Juno-2 On/Off Switch

UPDATE #2:

After using a Multimeter and checking for continuity all over the Juno-2, I’m finding zero problems. It really has me stumped. The only area I can seemed to properly check is the Power Transformer shown in the photo below. This sits in between the Power Supply board on the left and the Fuse board to the right. Both the Fuse and Power Supply Boards are 100%. Still when I turn on the Juno-2 below I get zero power past this Power Transformer. Could that be the cause? Not sure.

Juno-2 Transformer

********** UPDATE #3 ***********

I’m getting close!!

I have discovered through swapping everything around with a working Roland Juno-2 that there is a definite problem on the MAIN BOARD. The battery has been changed and reset procedures have been done, but there is still no sign of life. There must be a broken connection somewhere and so I’m now consulting the Service Manual. Stay tuned!!