Roland D-50 not working after replacing key

[bringmetacos]

Hey all, I’m trying to get my D-50 working again after replacing a key. I was able to replace it and reassemble everything properly. Now the display has 16 squares on the left side and it isn’t picking up midi.
It was working before I replaced the key. Any ideas? I tried replacing the battery but no change. Any help would be appreciated. Thanks!

[upunkt]

My first guess is reassembling was not properly enough.

Even if there is no sound information in memory (you still have PN-D50-00 card), the system should boot and give you some scrambled sound names. So the booting process seems to be stuck. It's not a display connection issue since the synth does not respond to MIDI signals.

So, all connectors connected? You can't mix them up, but doublecheck everything is in place. There can be loose wires hidden under the mainboard. I assume you did not try to connect a connector twisted by 180 degrees, guess that's not possible anyway. Reconnect and check you did not bend a pin by mistake.

If it's not connectors, you'll need equipment, a multimeter at least. You could try booting into test mode by holding "0" and "DECREMENT" and switching on but it's not likely that this will work.

Check if CPU (IC25 pin 64) and ROM (IC22 pin 28) receive their +5V on their dedicated pins, and ground. Schematics will guide you. If that's the case check for countinuity on address and data lines. If that is all working and the panel board is connected properly it should be possible to boot into test mode.

[madtheory]

Good advice! It's relatively easy to knock one of the many ribbon connectors in this synth. IIRC you have to unplug some to get at the keybed anyway?

[bringmetacos]

Thank you so much for your detailed response. I really appreciate it!
I will be going back in tomorrow and I will double check all of those things. I’m really hoping this is the case!
Even if I could at least get the midi working then I could use it for a nice controller. Obviously getting it completely working would be even better! I’ll let you guys know what I find out.

[bringmetacos]

Well, bad news. I thoroughly went through each of the connectors and pins and everything was perfectly in place no bent pins. (IC25 pin 64) and ROM (IC22 pin 28) we’re NOT receiving their +5V on their dedicated pins, and ground it was barely 1V. Not sure if there is a way I can turn it into a midi controller only somehow or if I need to replace something to get it going at all?

[madtheory]

Get the schematic, a combo head torch and magnifier (those headband things you might have seen a jeweller use) and trace back to the PSU from those pins. Dry joint, failed cap, or even a failed resistor. Dry joint is the most likely.

[meener777]

I had a similar display issue on an ESQ-1 (half the screen unlit, solid on the other side) and the cause was a bad inverter on the display board which was causing the serial comms from the main board to be scrambled as well as a blown display driver chip. Since there were two display driver chips half the screen wouldnt show anything at all. Not sure at all if that is your issue but its interesting that the symptom on the display looks similar. I think the advice given of checking power back to the psu is a good idea, continuity mode on your multimeter will help track down a bad trace. Power problems are usually pretty easy, be patient and methodical you got this.

[upunkt]

What madtheory says.

First of all, check for 5V in the PSU itself. You can grab it on connector CN3, as shown in the image. Pins 1+2 are ground, pins 3+4 carry +5V. Be careful, don't provoke shorts.

Roland D-50 PSU PCB

If you lack voltage, unplug the synth and first check fuse F2, then IC1 for continuity, then D1, then D3. Carefully reflow the joints of the voltage regulators. They heat up a lot so within many years these joints can crack due to thermal stress. If you still have no clue replace C6, C9 and C11 electrolytic caps with the same rating. Voltage safety maybe higher, but capacity should meet the exact rating.

If you have 5V on the PSU board follow the wiring. If wires are ok (continuity!) then follow traces on the mainboard. Check for dry solder joints at the connectors. If you plug/unplug a lot solder joints could simply break. So reflowing here might be a good idea anyway.