Discussion about the Korg PolySix synthesizer

The intense feeling of wanting to smash the thing will pass when you
eventually discover the problem, I promise! Have you tried swapping both
IC32 and 34 from another voice as a pair? Can¹t remember if we tried this?
Also can you verify that VR9 is still a 1M trimmer and has a range which
adjusts accordingly. Mark the position of it¹s current setting before you
start. This pots have a horrible habit of going dead where the wiper sits on
the carbon track for nearly 30 years!

If I have some spare time (ha!) I¹ll go into the lab and takes some readings
on one of mine...

Cheers,
Andy


On 24/02/2010 15:25, "Alexis V. Rogers" <alexis.v.rogers@gmail.com> wrote:

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> Okay, I've checked everything on the voice and here are the discrepencies.
> There is -1.2V at the junction of R218, R217, C50, and IC 35 pin 1. There is
> -1.2V across R217 to IC24 pin 1. There is also -1.2V at IC35 pin 2 and across
> the series of resistors connected to that pin from R141, R142, R143, R135 and
> the base of Q6.
> 
> When I hit a key to trigger this voice, D10 lights and the -1.2V on IC35 pins
> 1 and 2 goes up to -0.9V.
> 
> I removed IC35 from the socket (with the synth off of course) and performed
> additional measurements. With no IC in the socket I get -5V on pin 1 and a few
> mV on pin 2.
> 
> I'm not sure what to make of all this.
> 
> Thanks for any help.
> 
> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , Andrew
> Jury <andy@...> wrote:
>> >
>> > Oh dear! Guess you are going to have to make exhaustive comparative checks
>> > between working and the non-working voice to get to the bottom of this one.
>> > It would be interesting at this point to ensure C50 is OK and that the
>> > filter cut off bias voltage at pin 13 of IC32 doesn¹t vary to wildly from
>> > the others.
>> > 
>> > Cheers,
>> > Andy
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