Vintage Synth Repair

Thanks, Duncan.  It is an older model, without the cv in/out.  I found the user's manual and the service manual, but haven't yet found the adjustment procedures within them.  I did see 4 flat head adjustment pots, as you mentioned, but will likely un-mount the board for easier access.  (I won't have access to the synth until tonight, after work)  I'll try some things tonight and post again tomorrow with my findings.  For arguments sake, what if the tuning errors are NOT stable, IE, changing with time or temp as you mentioned?  

Thanks,

Dustin




________________________________
From: duncan <ferrograph@...>
To: vintagesynthrepair@yahoogroups.com
Sent: Thursday, December 4, 2008 1:50:57 PM
Subject: [vintagesynthrepair] Re: Moog Prodigy out of tune...


dustin-
a prodigy is a good place to start if you plan on learning how to
maintain an analogue synth, since they're quite straight-forward inside.
the problem you have there is a simple adjustment, so long as the
tuning error you get is stable & not changing with time, temperature
or vibration.
switch off the osc sync & set the interval controls (octave switches &
interval knob) so that the oscillators are in tune when you play the
lowest note. 
does the tuning discrepancy seem to be the same for both oscillators
or do they drift apart as you play up the keyboard?
is your prodigy a later model with cv in/out already fitted? if not,
you will need to get under the hood & find the test points on the
circuit board. keyboard cv is marked. it may or may not be tracking
correctly at 1V/octave... . there are adjustments for the key volts,
also for the cv buffer gain & for the tracking of each oscillator, +
high-trims for each aswell.

but before you go adjusting anything, make sure the keyboard connector
(carries voltage from the keyboard to the main board) is good. I
removed the plug & socket in my older prodigy & hard-wired these
connections for better reliability.

after this, you are going to need schemos & the adjustment procedure;
these are all over the internet & may even be in the files section
here. some of the adjustments can be reached from outside the case,
depending on the serial number of the moog, but you need a long narrow
flat-blade screwdriver with an insulated shaft.

let us know how you get on- we're here to help!

duncan.