Neumann W498 VCA compressor design

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Petrol Vendor
Posts: 8
Joined: Mon Nov 22, 2010 11:39 am

Neumann W498 VCA compressor design

Post by Petrol Vendor »

Hi folks,
I tried to post this over at prodigy, but the server seems to be down. I know this forum is intendet for new designs, but maybe someone here can help me out with some information.
I just bought a Neumann W498 stereo VCA from Ebay.
It seems ideal to me to be turned into a dynamic unit.

First of all, i would like to learn something about the unit.
On each channel i see a RC4559n dual opamp,
A Neumann 101 L VCA
Neumann OA 20
Small Haufe Transformer labled 216/6 90442
2 Pins on one, 3 on the other side
Large Haufe 2/4/8 90475 ST4143, it has a date stamped on: 6.02.81
2 Pins on one, 3 on the other side
A green block with 5 pins saying ERO BG 1883/3 M4

I found the datasheet for the Opamp and the schematic for the 101 but i have no idea about the other parts.

Any comments on these components?

i´m afraid i can´t even figure out what pins the 24V power supply is connected to....
It´s a 31 pin connector. I could imagine that there is a standard pin for the 24V and ground on these vintage broadcast modules?
The sheet i got with the unit doesn´t give the answer (witch i find rather surprising).
Problem is that the board is stuffed with large components, so it´s hard to follow the traces on the pcb.

http://audio.kubarth.com/rundfunk/ge...2YP9%268%60%0A

In the note it says that a solder joint has to be opened in order to use a dc controll voltage instead of up/down buttons (apparently some sample and hold or staicase logic is on the board)
It does not say what voltage range should be applied.
It does not say what soulder joint has to be opened.

Another thing of interest to me is if it is possible to run this module on +-12 or even +-15v.

Any idea?
Thanks alot!
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