"So here are some more photos:" - hudri
Wow, many, many thanks for those!
"On both boards, the IC is a TL072C opamp, and the adjustable inductor has marking 748N."
Thank you sir (or ma'am?) for that too!
"So who stole the chokes from my pitch oscillator, and why is this side working while the volume osc has problems? "
EDIT: IGNORE MY FOLLOWING BLATHER, THE CHOKES ARE IN THE PITCH ARM!
This is really unexpected, and runs counter to the info directly supplied by Moog's technical representative to those of us at TW here: [LINK]
Does the pitch side use a series EQ inductor to improve linearity?
I am not sure exactly what you are referring to but I will assume you mean the coil between the antenna and the oscillator. Yes, absolutely! We have a custom 3-Pi inductor wound for Claravox to match the antenna impedance with the L-C tank impedance.
It almost certainly runs counter to the pitch side voltage swing spec of ~35Vpp given in that same post, and could very well explain the pitch jumpiness documented by member tcordara on Claravox serial #34. I'm not seeing any ESD protection either (another Moog claim).
The Claravox pitch oscillator is quite disappointing. Why on earth would they remove those chokes, right at the beating heart of the Claravox?