Discussion about the Korg PolySix synthesizer

Hi,

 > 1. are *all* the electrolites worth replacing?
No, only those which are getting warm. Which ones are they? Usually
those in power supplies. The more current, the more heat. The higher
frequency the more heat.

 > 2. how on earth do you unsolder the main cpu socket (40pin i think)
 > without destroying all the vias? every IC i've unsoldered so far was a
 > tough job, unless i could clip the pins off.
Either you have a (good quality) desoldering tool: solder iron with
integrated vacuum sucker.
Or you have a desoldering "tip" for you soldering iron: this has the
size of the socket you want to desolder (DIL14, DIL16, DIL40, etc.). It
melts ALL pins of the IC / IC socket at once.
Or destroy the socket/IC and desolder each pin seperately.

 > 3. how do i go about with my apeggiator problem? where should i look?
 > just replace everything in its LED's path?
The ARP has a separate oscillator, built around the 555 (KLM-371/IC1).
Check the circuit of the 555. Download a data sheet from:
http://www.ortodoxism.ro/datasheets/philips/NE_SA_SE555_C_2.pdf
and read how it works.

 > 4. what wire should i use for repairing the traces? i want it to be
 > really thin and isolated.
Take a wire used for "wire wrap" method. Take the thinnest you can get,
e.g. 0.05mm2. Or take laquer (?) isolated wire like it is used inside
transformers.

 > 5. what do you recommend for cleaning the board? acetone? alcohol?
Alcohol. Acetone is too aggressive, it desolves the solder mask.

Good luck!

Johannes


jure zitnik wrote:
> hi guys, hi again.
> a have a story and a few questions.
> 
> a good year ago i bought a battery-leaked polysix and went through 2
> synth repair services, just to end up fixing it myself. nobody could
> fix it, after a month of being repaired troubles were still there. so
> i opened it up, made the battery mod, located the few bad traces,
> replaced 2 ICs and rewired the traces. and wow, it worked. it all
> woked except for arpeggiator LED. it was always on. and a few bank and
> patch LEDs were acting a bit funny too, but nothing serious.
> 
> yesterday i found out the subosc switch doesn't work. i knew soon
> after "repairing" the synth that the battery corrosion will continue
> to eat up traces, i should have removed all the damaged ones. so i
> opened up the beast, print out all the schematics i have and got to
> work.
> 
> after inspecting the schematics (and with the knowledge i acquired
> since the last time) i found out that the arpeggio switch isn't even
> connected to the programmer board (367).
> 
> so... the questions:
> 
> 1. are *all* the electrolites worth replacing?
> 2. how on earth do you unsolder the main cpu socket (40pin i think)
> without destroying all the vias? every IC i've unsoldered so far was a
> tough job, unless i could clip the pins off.
> 3. how do i go about with my apeggiator problem? where should i look?
> just replace everything in its LED's path?
> 4. what wire should i use for repairing the traces? i want it to be
> really thin and isolated.
> 5. what do you recommend for cleaning the board? acetone? alcohol?
> 
> please guys, help me. i want to do this once and for all. it's my
> favorite synth and i WILL make it work!
> 
> cheers,
> jure
> 
> 
> PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6 
> Yahoo! Groups Links
> 
> 
> 
>