Korg Poly61-M Issues and troubleshooting


#1

I have a Poly61 that currently doesn’t make any sound and the joystick frequency rate is the only thing lighting up and able to be adjusted. I have identified and changed out a few caps that each had single legs corroding near the cap itself, I have also changed out the battery with a new replacement. I’m still checking continuity on a few more molex connectors but have yet to get any signal. Any advice would be welcomed.

thanks


#2

If the old battery leaked and caused corrosion - a common issue with the Poly-61 and PolySix - then there could very well be PCB traces that need repair. It can affect components also, like ICs. If you had caps that had one leg dangling and corroded, I would strongly suspect that the PCB may be damaged from the corrosion, and the behavior you describe fits right in with this scenario.

The fix is pretty tedious - you have to test each trace on the board in the corroded area, and then repair any bad ones.

Just to be sure, when you replace the battery, you have to either use the same type of rechargeable battery (which is prone to leakage), or replace it with a lithium battery and modify the circuit a bit to disable the charging circuit (we sell a kit for this). Don’t use the wrong type of battery!


#3

Hey Sam, thanks so much for the reply.

Discussing this with a friend he suggested based on the issue that I double check the voltages coming from the psu. Up to that point I had already replaced the battery (which really hadn’t started to leak yet), several capacitors and one suspect resistor. After all that didn’t work I replaced the +5 voltage regulator (a LM7805) and everything powered up nicely.

Any suggestions on repairing tiny traces on the main board of a MicroKorg?

Thanks again


#4

If the trace has been cut somehow, you’ll need to scrape off the coating with a razor knife until the bare metal of the trace is showing, then solder a thin strand of wire to jumper over the break in the trace.

The other way to go is to locate a solder point (pad) on each side of the break, and then solder an insulated wire from one to the other.