Discussion about the Korg PolySix synthesizer

Hello,

I have spent the better part of the day sifting through old posts to
this forum, which proved very useful... I suffer from a certain
degree of phobia and ignorance when it comes to digital circuitry,
but it looks like I have no choice but to befriend the KLM-367
somehow, since most everything important goes through there. My first
analog synth, and the major problem is positively in the digital
section of it...somehow that doesn't surprise me. Anyway...

A number of people describe problems that (from my memory) I have
with my Polysix:

-Octave selector not working
-Waveform selector not working
-Sub osc. selector not working
-MG "MOD" selector consistently modulates VCO pitch regardless of
setting
-General patch memory problems

In addition, mine some times will "crash", and messing with the
tape enable/write enable selectors brings it back to life.

It seems common for these malfuctions to be part of the problem of
a failing KLM-367. Even so, major parts of the analog synth
(virtually all pots) work okay, so the damage is likely to be
somewhat limited, at least confined to the 367 board.

Clearly the stock battery in my P6 was replaced before the board
suffered serious damage, so I have some hope of being able to sort
this out.

It's going to be a few days before I get an opportunity to get back
to my shop to work on the machine, so I'll stay tuned here for
further input and go on reading old posts to prepare me for the
upcoming job.

Regards to all, from

Thomas/analogfuture

Have faith! My experience was that while it looked good initially,
only after removing the board and taking a look at it with light
shining throught the back was I able to notice the damage that was
done.

I would expect to have to rewire all of the traces to IC31. Check
the legs of IC31 as well. I found that particular IC was cheap and
readily available in my area in case it needed to be replaced.

Just take it easy and expect to spend several nights on KLM 367
alone. The results are *well worth it*!

Oh, and for what it's worth, I didn't have to replace any of the
buttons and pots in the end, they just needed a cleaning.

--- In PolySix@yahoogroups.com, "analogfuture" <dunker@o...> wrote:
>
> Hello,
>
> I have spent the better part of the day sifting through old posts
to
> this forum, which proved very useful... I suffer from a certain
> degree of phobia and ignorance when it comes to digital circuitry,
> but it looks like I have no choice but to befriend the KLM-367
> somehow, since most everything important goes through there. My
first
> analog synth, and the major problem is positively in the digital
> section of it...somehow that doesn't surprise me. Anyway...
>
> A number of people describe problems that (from my memory) I have
> with my Polysix:
>
> -Octave selector not working
> -Waveform selector not working
> -Sub osc. selector not working
> -MG "MOD" selector consistently modulates VCO pitch regardless of
> setting
> -General patch memory problems
>
> In addition, mine some times will "crash", and messing with the
> tape enable/write enable selectors brings it back to life.
>
> It seems common for these malfuctions to be part of the problem of
> a failing KLM-367. Even so, major parts of the analog synth
> (virtually all pots) work okay, so the damage is likely to be
> somewhat limited, at least confined to the 367 board.
>
> Clearly the stock battery in my P6 was replaced before the board
> suffered serious damage, so I have some hope of being able to sort
> this out.
>
> It's going to be a few days before I get an opportunity to get
back
> to my shop to work on the machine, so I'll stay tuned here for
> further input and go on reading old posts to prepare me for the
> upcoming job.
>
> Regards to all, from
>
> Thomas/analogfuture

Hi,

Check the line "P24" from the patch CPU (pin35 of IC22 on KLM-367). It
is the clock line for the latches for these signals (Octave, etc.)

"crashes sometimes": perform the "Reset Circuit Adjustment" as given
in the service manual. Check the TAPE ENABLE switch and its line to
the programmer CPU (pin 6 of IC22).

General: check all the lines from programmer CPU (IC22) to IC30/31
(data bus buffers), IC26/24 (adress latches, IC24 is errornously
labeled "IC34" in the schematic), IC32 (RAM), IC28/29 (digital control
latches), IC34/35 (digital control latches), and IC18/19 (analog
demultiplexers). From experience IC31 and IC30 are often affected
from battery acid eat-up, as they are located close to the battery.

Do all checks using an Ohmmeter.

Be patient and insistent - you will fix it and it is worth!

Good luck!

Johannes


analogfuture wrote:

> Hello,
>
> I have spent the better part of the day sifting through old posts to
> this forum, which proved very useful... I suffer from a certain
> degree of phobia and ignorance when it comes to digital circuitry,
> but it looks like I have no choice but to befriend the KLM-367
> somehow, since most everything important goes through there. My first
> analog synth, and the major problem is positively in the digital
> section of it...somehow that doesn't surprise me. Anyway...
>
> A number of people describe problems that (from my memory) I have
> with my Polysix:
>
> -Octave selector not working
> -Waveform selector not working
> -Sub osc. selector not working
> -MG "MOD" selector consistently modulates VCO pitch regardless of
> setting
> -General patch memory problems
>
> In addition, mine some times will "crash", and messing with the
> tape enable/write enable selectors brings it back to life.
>
> It seems common for these malfuctions to be part of the problem of
> a failing KLM-367. Even so, major parts of the analog synth
> (virtually all pots) work okay, so the damage is likely to be
> somewhat limited, at least confined to the 367 board.
>
> Clearly the stock battery in my P6 was replaced before the board
> suffered serious damage, so I have some hope of being able to sort
> this out.
>
> It's going to be a few days before I get an opportunity to get back
> to my shop to work on the machine, so I'll stay tuned here for
> further input and go on reading old posts to prepare me for the
> upcoming job.
>
> Regards to all, from
>
> Thomas/analogfuture
>
>
>
>
>
>
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