Discussion about the Korg PolySix synthesizer

Take a look at the traces around IC30, IC 25, R91 and C10.  
Especially the latter two.  If I remember correctly I had to rewire 
all of the traces near R91 and C10 which lead out to the circuits 
that deal with your patch button light (and related) issues.  I'm 
sure others here with a lot more knowledge can be more specific, but 
I had the same issue and it was resolved with the work I did on my 
KLM 367.


--- In PolySix@yahoogroups.com, "analogfuture" <dunker@o...> wrote:
> 
>  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