The Mysterious Polygram pitch/depth control

[montalbano]

Hi all guys
I want to replace is the Polygram pitch control, which started to work "so and so" well before removing the SP272 and doing the upgrade I recently did (new monitoring system, etc).
I already have a spare pitch control to install, but before doing that, I'd like to give the Polygram pitch a last chance, and refresh it. The problem that it is the only part of which I don't have any documentation. I also have the long "extender board", to do tests and measurements while the system is running, but NO schematics at all. And no manual.
It still works, I mean it doesn't cause overcuts, but it changed its behavior, like if something has been reset. This is common to all PS66 modules so it does not depend on them. Also, I've recapped all the motor driving boards (they are separate from the pitch control boards, which are mostly including CMOS, Multiplexer/Demultiplexer, op-amps, an A/D converter and a few other things). Even tried to swap them, no change.
Insofar, I've simply managed to check the two PS boards (they are the most external ones), because you know one starts from the major stuff like power supply, main capacitors etc. But as for the rest, I can only guess what the other boards are for. And I am not the type who likes to tweak here and there, just to "see if something changes".
Following Aussie's suggestion, asked Mike Marsh at the Exchange, he is very kind ... but when he had that pitch control unit, he had no documentation of it, as well. Neither has the new owner of his VMS.
There must be someone somewhere who has worked with this pitch, I mean ...

[Phinster]

Speak to Crispin Murray at 07724 751065 ..tell him Pete Norman gave you the number

[flozki]

hello Phil
just save time and energy and go for something contemporary and professional.
there where studios spent easy the double of what a new solution costs in hope to fix.
now they are happy owners of a nice vinylium or flokason controller.

this spolygram tuff is longtime end of life and the full documentation was never available.
only a few units where made. maybe 10 or so. and many had unddocumented mods.
i know what i am speaking of as we had one of those.
the only one who knew it really and all the different mods. was
Mr. Struck and he died a long time ago.

plus he polygram is only feeding in the signals into the old neumann electronics.
tacho's of the vms70 motors are all worn out the whole system with belts....

if you want to cut on pro level . go for a pro solution.
restoring polygram is just loosing time & money.
my 2 cents.

[dr.crippen]

Have sent you a PM, message me on WhatsApp on the number Pete N supplied.

[montalbano]

I have found where the problem was and fixed it.
I would like to thank all the people who gave me good advices, especially Crispin.