Moog Prodigy
Prodigy Quick Tuning Reference
The Prodigy is a really neat Moog. It has a great sync feature that changes the function of the pitch bend to allow the pitch bender to function as a manual sync sweep control. It does this by assigning the pitch bender only the Oscillator 2 while in sync mode.
The Prodigy uses CA3046 transistor arrays for the exponential converter. One of the transistors in the array acts as a small heater to keep the entire chip at a constant temperature to stabilize tuning. This is the same idea as the µA726 chips found in earlier Moogs (Mini Moog and Sonic Six). Unlike the long gone µA726, the CA3046 is still fairly easy to obtain as a through hole part, and still in production as a surface mount part.
The "heater" transistors are labelled Q5 for Oscillator 1 and Q10 for Oscillator 2. These transistors are found on the CA3046 ICs. Q6/Q12 are current sinks for the "heater" transistors. I've included notes on how this circuit works in the tuning guide. It is important to check that this circuit is working and know how to adjust it properly. The service manual doesn't explain it at all.
I've serviced quite a few Prodigy models at this point, and a dead or faulty CA3046 has been a common problem. The symptoms will either be a dead or untunable oscillator. The array ICs are usually socketed, so swapping ICs is easy. If one oscillator works, and the other doesn't, you can try swapping the ICs on the board, or if through hole CA3046s are still cheap enough, I would buy a few to have on hand.
The above tuning guides are what works for me. I used the Prodigy service manual as a guide and then proceeded from there.
There are at least two different circuit boards with different part designators used on the Prodigy keyboards. Double check the parts designators by seeing what the trims actually connect to on your particular Prodigy. The boards are laid out almost identically, but for whatever reason the designators got changed.
If your Prodigy has a "OSC IN" jack, which is a 1V/Oct CV input, then tune up with that jack first, then make the Prodigy's keyboard match that scaling. See tuning guide for more info.