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

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Subject: Re: Problem with new KLM-367A

From: rnw6ueo2ru3grihf5iabauttna56367yo4n5umk4@yahoo.com
Date: 2017-04-25

Hi Everyone,

I am currently rebuilding my Polysix and have replaced the battery damaged KLM-367 with one of Jed's new KLM-367A boards. Everything worked great for a while but recently the front LEDs have locked on Programs 1 and 8. None of the Bank LEDs are lit, nor is the Manual button, and they do not respond when pressed. I tried resetting the circuit per the service manual, but to no avail as the LEDs will not return to Bank A and Program 1. 

Per this thread I also tried replacing C23 with a 10pF ceramic capacitor. While this did bring the amplitude of XTAL 1 and XTAL 2 closer together, and I was able to confirm a 6MHz input at each point, it did not solve the issue. I then probed TP4 (Clock) and noticed there was a weak signal that did not resemble a clock waveform. Could this mean my RAM chip is defective? Has anyone else experienced this issue before? I have attached photos of the scope readings for reference.

Thank You,
Daniel