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

Another session yesterday. Cleaned all pot/switch boards in control
panel. Gobs of filth came off, still haven't gotten the stink of old
nicotine out of my hands. The rest may in fact have been coke,
judging from the stickiness of it. Some job!

There are still some problems with the KLM-367. I still get the
intermittant uh...altered state, characterized by the following:

∗Signal amplitude (EG INT?) drops a lot.
∗Waveform distorted ("glitches" on any waveform)
∗Pitch instability

The synth may suddenly pop into this state without my touching
anything, other times it happens while turning a knob or working the
keyboard, apparently as a result of some data going in wrong places.

In the "normal" state, all above symptoms disappear and when setting
to "manual" all data throughput and controls seem to work 100%, VCO
waveforms look good, level and pitch stable. I have studied the
schematics some more and assume the DAC and the analog demuxer to be
OK. Will continue to look for problems around IC 26, 34, 31 and 30.
(Probably will mount sockets and fresh CMOS chips anyway.)

LEDS 'Bank D' and 'Program 4' are still more or less permanently
lit, the patch memory selection is generally screwy, as well as HOLD
and CHORD MEMORY buttons not working. LEDs "D" and "4" are totally
unaffected by adjustments to the reset pot and the DAC trimmmers.
(I'll take a closer look at the tact switches (test for shorts), and
look more closely at DO0-DO3. Wouldn't be surprised to find a short
from +5V to some wrong place.)
With switch set to "test" and adjusting VR7, I can't get LEDs 2 and
7 to light up, will get 8 to change to 7,6..., but LED 1 stays lit.

analogfuture