Discussion about the Korg PolySix synthesizer

So things are looking a bit worse by now.

I can no longer successfully make the D/A adjustment. This actually had
happened before but the problem had disappeared for a day or so (after
reflowing all possible solder joints). The symptom is that VR6 does not
shift the offset of the left LED. As an example: If I call up the D/A
adjustment routine LED's 4 and 8 light up. By turning VR6 I can make LED 8
move to 7 or 6, but LED 4 stays on all the same. VR7 seems to do what it
should - however I cannot get lower than LED 4 in any case.

Given the other problems the KLM367 has at the moment I'm a bit reluctant
to make a definitive judgement now (perhaps it is just a display problem
and the adjustment procedure actually works?). I've measured all the
continuity around IC33 and everything looks ok; I also swapped IC27 to no
avail.