Vintage Synth Repair

Look for a leaky transistor in the chorus circuit. The general purpose NPN and PNP 
transistors that Roland used in so many machines seem to fail quite often. They begin to 
leak and cause pops. I come across them with leakage problems in TR909's all the time, in 
JP6 power supplies, and Juno 106's. They are 2SA115's and 2SC2603's. From memory 
these are used on the Juno chorus/output board as well.


--- In vintagesynthrepair@yahoogroups.com, "Scott" <painintheamp@...> wrote:
>
> --- In vintagesynthrepair@yahoogroups.com, "Dorus Manassis"
> <thorosm@> wrote:
> >
> > --- In vintagesynthrepair@yahoogroups.com, "gil_we" <gil_we@> wrote:
> > >
> > > Is there any particular component on the Juno 106 amplification/chorus
> > > circuit that could cause one side to make a "tick" noise with every
> > > LFO loop ? 
> > > 
> > > It may sound louder on one side compared to the other, if that
> helps...
> > > Replaced the BBD's but no change. Thanks !
> > >
> > 
> > i think i have the same problem with my MKS-50....
> > 
> > i would be interested to know too....
> >
> Does that part of the circuit have a potentiometer?
> Most discrete chorus circuits Ive seen have a pot that needs to find
> the "sweet spot" where the oscillator works but doesnt overwork
>