Discussion about the Korg PolySix synthesizer

On Mon, 24 Nov 2003, toorglick wrote:

> Are there trace maps available anywhere? I was looking at Old Crow's
> site again and saved some of the shots of the trace maps he uses in his
> guide to fixing the battery damage. I already noted an error in the
> prior repair done to mine and a few traces that need repair but weren't.
> I think I can get by with the shots from Old Crow's, but a complete map
> would be handy.

The trace diagram is in the service manual. It does not copy well
unless you use a good greyscaling copier. The parts of it I show I did
just by photographing the page.

> Questions: here's my inexperience showing through, but, where the
> traces switch from top to bottom (or bottom to top, as it were), a lot
> of those solder points had corrosion on the top of the board. Now, what
> I did was first clean the board with alchohol, then I slapped some
> baking soda paste on that section of the board, let it sit, then
> scrubbed (lightly) to clean it up and neutralize any remaining acid.
> Most of those solder points clean up well, but I'm wondering if I need
> to drop some fresh stuff in those holes, or if I can just reflow them?
> Would I do either from the top or bottom of the board?

Check to see if they conduct first. If they do, don't add any more
solder. If they don't, you will want to solder in a small piece of wire
to close the circuit.

> What functions do ICs 30 and 31 handle? Are either of these
> the "programmer IC?"

Those chips are just bus drivers so that signals can be sent a few feet
(to the front panel) without overloading the CPU. The "programmer IC" is
IC22, a microcontroller that is pre-programmed to operate the KLM-367 as a
patch manager.

If someone has a broken IC22 I can program a new one for cheap.

> The legs on both are definately in tact; they seemed to have survived
> the acid bath fine (I think IC 31 was replaced because it looks more
> "fresh" than the other ICs and a trace was removed from underneath it),
> so there's no reason to remove them, yes?

Shouldn't be, as long as there are no missing connections/traces.

Crow
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