Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

Hello guys,

I've bought a polysix in quite a good shape but electronically non functional, so i started to troubleshoot.

At first power, there are 3 voices comming up, sometimes one, at each start and they seem to have the same pitch. Modulation and Bend works. Tune knob works. Except these, the bank lights come up heratically.

Adjusted the power supply to be +15, - 15, +5 on the spot.

I noticed 2 of the 4 latches chip 74ls75 on the panel board were marked by somebody with an X so I figured these need changing.

Keyboard seems to affect the pitch slighly when pressing more than 3, 4 keys.

Arpegiator led is flashing and rate is adjustable.

My guess is the KLM 367 is causing the problems, so i verified the traces around IC 31 and resolder them back in place.

Now, I have no idea how to check wheter the CPU, RAM, DAC or LM13600 are working fine, but I probed the CPU using an Oscilloscope and the clock was there at 6mhz, and on some other pin there seem to be data flowing.

Somebody with more experience to privide guidance ?