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

Hello,

I've did some tests today and here;s what i found:

TO CONFIRM: cpu seems to be working fine since i was able to see the clock on TP4 on osciloscope. Strege thing that somebody mentioned the gap should be 20 ms and i meassured 10ms. Is this ok ? Also the TP2 spot looks ok - The multiplexed signal from the pots it is there.

PROBLEM: there cpu starts randomnly. A few power off - power on cycles are necesary to get the clock there. I this this is related of the bad 4 x 74ls75 found on the control panel board. Two of these latches seem to be dead.

PROBLEM: Altoought there is sound presend, and lfo, cutoff, and all the other pots are working, the sound is non interupted, very loud and at a rather high pitch. voice 6, 5, 4 diode leds are light up, and the sound resemnbles like a few vco beeing active. the other 3 leds, for voice 1, 2, 3 are off. touching the keyboard changes the pitch slighly but then resumes the state before. I'm suspecting the latches: 74ls75

QUESTION: how to test the key assigner cpu ? Is there a method simillar to the uC found on KLM 367 ?

Thanks for support guys.

Razvan