Discussion about the Korg PolySix synthesizer

The 4xxx IC family tends to go bad when old


--- In PolySix@yahoogroups.com, "Gregor Quade" <u3dreal@y...> wrote:
>
> Thanks alot Gil,
> 
> I already checked all the traces on the board which might got
> affected by the batteryleak. So far they are all working fine.
> 
> The Tip with the logic IC on the frontpanel is very good.
> I'll try that. I also thought of that. but i wasn't sure.
> 
> Update to come soon.
> 
> Still if anybody has advice i would appreciate.
> 
> thanks to all.
> 
> Gregor 
> >
> > > Hello all;
> > > 
> > > I bought a polysix in rather bad condition...
> > > 
> > > I did the batteryreplacements and checked to circuits...they 
seem to
> > > be OK for both sides of teh PCB 
> > 
> > Make sure it didn't experienced any battery leakage. You can look 
for 
> > green rust on the PBCs and the components on both the computer 
board 
> > and the one that is place above it, attached to the panel. If it 
did, 
> > you'll have to rewire some traced and replace some parts that may 
got 
> > defected by the acid...
> > 
> > 
> > > ...many things were still wrong then I replaced the IC31...and 
the 
> > octave 
> > > knob and the sub osc were working again.
> > > 
> > > The Controls are better now but still don't work correctly..
> > > 
> > > the MG....Delay doesn't work at all and Level gets controlled 
by the
> > > VCO PW/PWM knob...? the EG doesn't seem to work either..
> > > only the sustain can be controlled via the LFO resonance knob..
> > 
> > I had similar problem on my Trident, which I solved by replacing 
a 
> > few logic ICs on the panels, which were directly related with the 
> > knobs that didn't work properly. In on case I found that a 
technician 
> > who tried to fix the machine, has placed on IC one of the ICs in 
> > reverse !!
> > 
> > 
> > > 
> > > all the other things like the preset section / loading saving 
> > progamms
> > > or even sending and receiving banks form external casset 
recorder
> > > works....!!!!!
> > > 
> > 
> > So the computer board seems to be ok.
> > 
> > > when i try to do the testing procedure with the 56k 
resistor...the 
> > > following happens.....when i turn the trim clockwise there is a 
> > point 
> > > where is jumps from bankA prog1 to all eight 
proglights.....this 
> > doesn't 
> > > happen 
> > > for me the two first ( prog 1+2) don' light...sometimes 
> > > its only the first one which doesn't light...
> > > when i remove the resistor it switches back to prog1 bankA
> > > 
> > 
> > Normal ?....
> > 
> > > I have no idea what could be wrong...could it be IC30 or even 
the 
> > > processor ?? Did you have something simlar ? 
> > > 
> > 
> > I would check/replace the suspective ICs on the panel board first.
> >
>