[sdiy] Juno 106 Repair Help

[Travis Thatcher]

I'm working on my friend's Juno 106 and only have 2 frustrating
problems left to work out.

First, the sub octave on voice 3 does not sound.  I have the service
manual, and schematics, but I'm not quite skilled enough to know
exactly where, and what to check for where the problem might be.  Any
tips would be a great start.

The other problem is with the pitch bender.  I replaced the bender
unit with one off of another 106 that was supposedly functional.  I
checked and it is getting the proper power on the way in, and all
functions on the module work except for the bender itself (though it
does trigger the lfo mod).  I trace the signal path from the pot on
the bender, which does give the proper +- voltage operation at its
initial connection to the pcb. On other end of the pcb, where the
cable connects to the voice boards, pin 11 has no voltage on it, no
matter how the bender is moved.  I checked by applying a voltage
directly to the voice board (3v) and it does 'cause the pitch to
increase.  I also started looking at the output pins of the op amps.
Pin 7 of opamp 1 goes between 0v and -3.3 either way you move the
bender, but i'm guess the diode that comes next will not allow this to
pass through? I assume that the bender pole line determines whether
its a positive bend or negative?

Sorry if this is all a bit vague and niave...I still have a lot to
learn.  Anybody else have any similar problems?

Thanks,
Travis
-- 
http://www.judichicago.com
http://www.myspace.com/judichicago
http://www.recompas.com
http://voiceofsaturn.blogspot.com