Discussion about the Korg PolySix synthesizer

Hi,

If you are certain you have performed the reset procedure (with the 56K
resistor) and the A/D convertor calibration then you should definitely be
re-examining data bus lines DO0 thru DO8. The logic here will determine the
LED and switch assignments (amongst other things). Even if you have spent
time performing cold resistance checks it would to worth using a logic probe
(one which can be used to look for pulse trains) at either end of the data
bus to ensure you have the appropriate logic when you view and operate the
patch assignment keys and LEDs. For example start on the KLM 371, obtain a
datasheet for the 72LS75 and study the truth tables for these devices. Try
operating some of the buttons and see how the logic decodes. It is a bit of
a grind, I am afraid, but I feel certain that you still have a one or more
intermittent open circuit tracks.

Cheers,
Andy


On 08/01/2010 21:20, "ML" <f115@rocketmail.com> wrote:

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> Did nothing.
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> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , "ML"
> <f115@...> wrote:
>> >
>> > Thanks! I'll do that and see what happens.
>> > 
>> > 
>> > 
>> > --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> ,
>> Johannes Hausensteiner <johau@> wrote:
>>> > >
>>> > > Do the Reset adjustment.
>>> > > 
>>> > > ML wrote:
>>>> > > > With my first polysix tuned up I started to set my sights on a second
>>>> P6 I have here. This one is a recovery project i picked up.
>>>> > > >
>>>> > > > It has a handful of problems. The main issue is that it doesn't allow
>>>> patches to be switched. It stays locked on one patch and multiple Patch and
>>>> bank LEDs are lit. It also has the same problem with the MG as my first one
>>>> did. It intermittently tiggers the maximum MG level.
>>>> > > >
>>>> > > > I started looking at it more carefully. It actually had a cold solder
>>>> joint on one of the MG level pins but fixing that didn't repair the
>>>> problem. This P6 needed the battery mod done too. I installed that and then
>>>> replaced IC30 and IC31. For a very short while I managed to recover the
>>>> bank, patch, and write functionality but somewhere during this process it
>>>> died again and is back to running one patch and multiple bank / patch LEDs.
>>>> I'm quite certain I covered all the traces properly because I even had to
>>>> add a few wires to connect points and the corrosion isn't major on this
>>>> card. Do you have any suggestions on other ICs that may need inspection?
>>>> > > >
>>>> > > > Also - it would be great to understand the board better. Does anyone
>>>> mind elaborating on the specific tasks some of these ICs have?
>>>> > > >
>>>> > > >
>>>> > > >
>>>> > > > ------------------------------------
>>>> > > >
>>>> > > > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6Yahoo!
>>>> Groups Links
>>>> > > >
>>>> > > >
>>>> > > >
>>> > >
>> >
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