Thanks for your input, everyone.
I allready re-capped the PSU, no other elcos in it. I got this for authenticity and historic value (it would probably be the first commercally available Quad encoder?), and allready have CBS SQ encoder, so two more to go
(Well 4, if we count Denon, but I dont think thir matrix encoders where commercially available, and I think same goes for RM encoders in all disguises - sans Sans-sui - if you want to call it RM)
So would prefer to keep the op-amps - if I can get them working. Easy enough to try it with better op-amps later, as it has a plug-in base for op-amps. What would you guys recommend as a pin-compatible direct replacement?
When I say behaving strangely, when I connect the inputs, the moment when ground on input gets in contact, the unit starts oscillating on output (about 5khz). Loudly. My best guess is that the output XLRs are not wired in a (what we would call in 2020) standard way, and that the unit essentially short-circuits on inputs.
This is a non-balanced (single-ended) model variant without output transformers, so I'm using the XLR-RCA adapters (that of course have minus pin bridged to the ground)
@Sonik Wiz - do you still have that EV4 encoder, I am looking for one?
BTW - one of the articles I found on this unit, mentiones that it is actually both a DynaQuad and EV-4 encoder - is this possible? The "diamond" / square switch I thought is just for the Dynaco Diamond original layout vs the later square one... (I dont have any manuals whatsoever)
Thanks,
Andrej