Discussion about the Korg PolySix synthesizer

This is not an unusual pattern: your polysix
suffers from battery leakage, you repair it,
but some functions do not work. If you
investigate, you find that even more pcb traces
were affected by the battery acid. It is very
important to clean the pcb thouroughly. I use
alcohol for this purpose. Only when you are
really sure that all acid is gone start building
up the pcb. Additionally I route wires on traces
that are still intact now but have this ugly
dark look. You can expect them to fail within
a short time. The acid crawls under the solder
mask along the traces and is still there.
---
So I wish you the best in finding ALL affected
traces and lines.
It certainly is not a DAC problem when you can
here your other patches (from memory) normally.
It couls be a problem of the analog multiplexers
found on KLM-369, KLM-370. You can check this
easliy: put a scope to IC27/pin1. The schematic
says that there is a test point but I cannot
find it on the PCB drawing. Trigger the scope
with the signal from test point "Clock" near
IC22. You can se now the multiplexed analog
control voltages as output by the DAC. Now
move the probe to CN11-pin2 (this is called
"data" in the schematics). Here you can see
the multiplexed CVs as they come from the
control panel. In MANUAL mode the individual
CVs' levels must be the same. The signal will
look different timing-wise as the DAC also
"converts" all other data bus activity.

Good luck,

Johannes


--- petercaja <pero@radiocity.si> wrote:
> Guys, thank you for replays!
> 
> After spending a little more time with PolySix, i
> discovered one more 
> broken trace, caused by battery leakage, i found out
> that i can 
> acctually copy preset from let's say A2 to A1, so
> write is working, 
> however, i can't write from MANUAL mode.
> If i set a patch in manual mode and then write it,
> the preset is 
> overwritten, but not with the patch it should but
> with - something.
> I also found out that if i make drastic changes to
> the sound and 
> rewrite the patch, there is a difference, but it's
> far from the sound 
> from MANUAL mode :-)
> 
> Could it be a DAC problem? 
> Another thing that i'm not sure about is Reset
> Circuit calibration.
> According to the manuals, BANK A-D, MANUAL, TAPE
> ENABLE and PROGRAM 1-
> 8 leds should be lit, what about HOLD, CHORD MEMORY,
> UNISON and POLY?
> If i set VR1, sometimes POLY led goes out and UNISON
> led become lit, 
> sometimes all four leds are lit (during the
> calibration process).
> 
> So, to be short: I can COPY preset from one place to
> other, but if i 
> write from MANUAL mode, the values stored are
> different from those 
> set by pots :-)
> 
> Best regards,
> Peter
> 
> --- In PolySix@yahoogroups.com, The Old Crow
> <oldcrow@o...> wrote:
> > 
> >   Oh, Greg has a point; if the write enable is not
> actually getting 
> > through, then it won't write anyhting.
> > 
> > /**/
> 
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