[sdiy] Korg Polysix Problem

[Chris Manders]

Hi

I just wanted to thank everyones input and help given
to me, on what might be the cause of my ailing
Polysix.

It is now fixed!
Strangely, I tracked down the fault and it was caused
by a loose/damaged TAPE switch. The Polysix was
permanently in tape mode - When you are panic stricken
at a gig, you forget to look at little things like the
tape switch light which was permanently on! I must
have thought it was all part of the problem with it
'crashing' on me, so to speak.

Still, during this repair / fiddle with the beast, I
did get the KLM-367 CPU board out once more and
examine my previous (good) repair handywork on the
battery damaged tracks.
I also did the nice little 'D to A' calibration on
this board, which I have never accomplished before. I
am glad I did too, as it was quite 'out'.
One thing I MUST say in the defence of the Polysix, it
is an engineers dream to work on!!!! Pop open and the
case, swing back the top lid and all the gubbins is
there for you. Individual LEDS on the sound board for
each voice JUST FOR THE ENGINEER!! to see which voice
is firing.
On the negative side, the patch buttons really are
naff. They feel awful, and I know are prone to wearing
out.

I got GIVEN this Polysix around 1995 in BITS. I mean
TOTAL BITS, in two black bags.
I would guess that the previous owner had certainly
had it die from the battery damaged board, and had
ripped it apart for some reason.
I put it all back together and the only thing it
really needed was one of the SSM filter chips
replacing, a few of the plastic patch buttons
replacing and of course the battery damage repair as
mentioned.

The only thing I have not repaired on this Synth is
the SUB OSCILLATOR - It does not work at all.
I have tested the Suboscillator switch, and tracked
back all the lines to the KLM-367 board as best I can,
and everything seems OK. The next thing would be to
replace IC29, a 4042 IC which present the data of the
switches on to the Data bus when called for.

I have yet to really use my Polysix in anger. During
my gig, I was going to use it for a PAD on one of my
songs.

All the best
Chris

http://www.myspace.com/uberlasermusic


--- Tom Wiltshire <tom at electricdruid.net> wrote:

> 
> On 2 Feb 2007, at 17:28, Oakley Sound wrote:
> 
> > Battery leakage is not always cleaned up in one
> job. The corrosion can 
> > still continue undetected inside the chips, or in
> the vias. I would 
> > beep out the lines again and see if you can find
> the discontinuity. 
> > Look again at the usual suspects all around the
> cell location and 
> > those two 74LS chips.
> >
> 
> I'll second that. They sometimes give up again later
> - mine did. That 
> it should happen when you're just about to start a
> gig should come as 
> no surprise...
> 
> 
> 
> 
> ++++ Electric Druid ++++
> Web Design & Development
> http://www.electricdruid.net
> 
> 
> 



 
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