Discussion about the Korg PolySix synthesizer

Hi Don,

You almost certainly have track disconnections. Try and focus in on two
places of the Œ367. First the data bus DO0-DO7 and the multiplex address bus
INH1-3. Using your scope scope ensure that you have at least what look like
Œtrains¹ of data pulse when you operate the controls. I find when dealing
with multiple problems like this it pays to select one of the problems and
focus in on it. Usually everything else will start to become apparent as you
make progress. Before you start, however, are you able to perform the reset
calibration procedure correctly? If you can verify this then we can proceed!

Cheers,
Andy

On 16/01/2010 13:56, "longenough2002" <backshall1@bellsouth.net> wrote:

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> Just got a Polysix in with some bizarre symptoms. It had an old battery
> in it that looked like it had just started to leak. Only a couple of
> traces had some black spots and still checked out okay with an ohmmeter.
> I put in a cr2032 and diode and it is saving patches okay. It's not
> until I twiddle some knobs that things start to get weird. Here is what
> works: Output, Bend, Tune, VCO, VCA, Arpeggiator, Key Assign, Programmer
> sections all OK. Problem sections: MG, VCF, EG, Effects. By Section: MG
> - Frequency, Delay and Mod work, but Level seems to be controlling VCF
> Cutoff, not modulation intensity. VCF - Cutoff does nothing, Resonance
> works when set between 5 and 10, but seems to control Attack when set
> between 0 and 5, EG Intensity does nothing, KBD Track works. EG - Attack
> does nothing, Decay works, but in reverse, as if EG Intensity is in the
> negative range. Release works between 5 and 10 but seems to do nothing
> between 0 and 5. Effects - switch works, but Intensity does nothing.
> It would seem the D/A is having serious problems, and I can't get LEDs 1
> and 8 to light up during the reset procedure. I get 1 and 5. I wish the
> service manual had some voltages to measure, instead of just watching
> lights. The +/-15 and +/-5v supplies look good. Anybody have ideas where
> to start debugging this? I have a scope and multimeter, but no logic
> analyzer. Thanks for any assistance you can provide. Don B.
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