Roland RD300GX Parts

Hello, I just picked up a Roland RD300gx Digital Piano. Some of the keys don’t work but that is a fairly easy fix, however, the LED switches under the display don’t work. Most everything else on this board seems ok and looks ok when I opened it, no obvious problems, all connections are tight. Does anyone know what might cause these switches to fail? Without them functioning, I cannot reset to factory or use any tones below the first tier. Thanks!

I’ll add another note about this keyboard. I attempted to clean the contacts for the dead keys with 91% Isopropyl alcohol and that did not bring back them back to life. Anything else to try? Thanks.

Alcohol can cause the rubber of the contact strips to dry out and crack eventually - it’s better to wash them in warm water with dishwashing soap. It’s okay, I think, to clean the carbon nubs with alcohol on a Q-tip.

You might want to also clean the contact PCBs - if there is some grit on them, it can stop a note from playing. You can bathe them in the same dish water, or use alcohol to wipe the boards down.

Swapping contact strips around can tell you if a dead note is from a bad strip, or a bad PCB contact. The 12-note strips are no longer available from Roland, but we do have a couple of the smaller strips available - that might help some.

For those panel switches, do NONE of them work, never-ever-ever? If that’s the case, it may be a problem on the circuit board, or with the wiring connection. But if some work and some don’t, or if you can get them to work by pressing extra hard or pressing a bunch of times, then it will be an issue with the tact switch, and you can replace those:

Thanks Sam. The LED switches don’t work at all no matter how you press them. The key issue is the killer for this board. I did pull the contact PCB and swapped the pink contact strips. If they were faulty, I would expect new notes to be dead. Not the case. The original notes are still dead. The Dead Notes (Name for a band?!) are A1, C#1, F2, C#3 and A3. I hope my numeric designation is correct. If I can get the notes to work, then I can try replacing the switches.

Sorry not include this in my previous post. I did clean the PCB contacts with alcohol and had some black residue on my cotton swabs. Still nothing. The pink contact strips, as well as, the inside of this board look great. A mystery. Thanks!

There could be other problems with the contact board - a bad trace, faulty diode, or a bad ribbon cable perhaps. Any of those issues could cause keys to be dead. I will check tomorrow to see if those boards are available.

Thanks for the update! I’m guessing this keyboard had some sort of traumatic event to cause these problems!

Only the lower contact board is still available from Roland, and we don’t have any of these boards available used. So it sounds like it’s time to do some diagnosing to find if the trouble is with the contact boards, ribbon cable, or whatever, and then determine if it can be repaired.

Thanks Sam,

How would I get the lower board from Roland? I just got off the phone with a local Roland Service tech who said he couldn’t get any parts. Thanks!

BTW, the ribbon cables, and traces look ok. I don’t have access to a microscope so there could be a break in a trace. Having a schematic diagram for these boards would be a big help but online resources for this particular model are almost nonexistent.

I don’t know if anyone is reading this thread but I found keybed pcbs on eBay. I ordered them and they arrived today. I installed the lower and mid board and no more dead keys! Hoping the LED switches I ordered from Syntaur fix the access to lower tier voices etc (INC, DEC, EXIT, etc). Not sure how to proceed if they don’t but at least I now have all 88 notes working on the primary tone tier.

You can test the switches while they are still installed on the panel board, using a multimeter with a ‘beep’ setting (i.e. it beeps when there is a closed circuit). Just put the meter leads on the solder pins of one of the switches, and press the switch. If the meter beeps when the switch is pressed, then the switch itself is working, and the problems you are having must be elsewhere.

It seems odd that every single switch would stop working completely - but if something got spilled in there, perhaps that could cause it to happen. But it may be that something else is at fault.

It was a crap shoot and I should have probably known it wouldn’t work. It didn’t. Not sure how to proceed. All 88 notes are now good but I only have access to the first tier of tones. The LED switches below the LCD screen are dark. There are diodes next to these switches but at this point, I’m out of my league. Without a schematic diagram there is little anyone could do to fix this board. Roland service centers are only capable of replacing entire boards not components. If I’m lucky I can use this as a MIDI controller but not much else. Without access to the four LED switches below the display one can do very little on this system. Thanks for all who provided assistance!

The left panel board is still available from Roland (it would have to come from Japan), but I wouldn’t pursue that. If there is trouble with your board, it is likely an easy fix - repairing a trace or two would be far easier and quicker than trying to get that board.

Those switches just run directly to the wiring connector which leads to the right panel board, so you should be able to follow traces and wires and then be able to test the switches with a beeper at the right panel board. If that works, then you know the problem is not with the left panel board. You can probably then trace them all the way back to the main board. That will tell you if there is a break in the circuit somewhere (like a bad connector or wiring harness) or, if all that is working correctly, that there is a problem on the main board.

Thanks again Sam! I had good continuity from the switches to the connector on the left panel board and eventually to the connector on the right board. So I guess I can rule out the Left Board. Next I’ll try tracing from the Right Board connector. Going to take a break from this for a couple days. If it’s a problem with the main board, I guess I’m done. That is all SMT stuff. I doubt that board is available anywhere!


Sounds like a practical approach. If Roland did have the main board available, it would likely cost more than the keyboard is worth. Ditto for paying a tech to find the faulty component and replace it. But maybe you’ll get lucky and find a bad solder joint or broken wire on the path to the main board…

I’ve been tracing on the right panel board and it seems there are a bank of 7 transistors and 2 IC’s. I am wondering if any of these components enable the 4 LED switches to allow a user to access the lower layers of tones and system configuration. The two ICs are: HD74HC245P and HD74HC138P. There appear to be two types of transistors with the marking of 2227 8E and C114 ESG. The ICs seem to be available but the transistors seem to be harder to find. I’m thinking since these components are cheap would it make sense to get them and replace the components on the Panel R board. It would be helpful to have a schematic or a block diagram but there is so little information on this keyboard. If the main board is the problem, would it work at all? It is minimally useable at present with 8 first tier tones. It appears most of the panel buttons do work. The exception is the 4 LED switches under the display.

The full transistor designations are DTC114ESATP and RN2227 - hopefully that can help if you need to replace them. It sounds like a good approach, to replace those and the ICs on the right panel board. At least an inexpensive approach… If that doesn’t solve the problem, at least it builds character!

Thanks Sam! Those numbers are mighty helpful! You wouldn’t happen to have a block diagram or a schematic of this board would you? If the ICs and the transistors don’t fix this then I’ll hopefully still be able to use it as a MIDI controller, unless the INC and DEC buttons are needed to use that mode.