Studer comp/limiter voltage ... clear this up please ??

[MartyMart]

Can someone give me a definitive answer on this ?
Just sent off a damaged unit from the xmas gift thread and i have another
to look at too.
Nele has recieved the unit and has asked me.
Schem appears to say it runs on 0v and -21v DC !!
That seems very odd, the service manual from a site linked here says it operates from +20v to +22v DC
Have they just used the "-" sign in the text or is this the most odd powered
unit that I've ever seen .... surely you would only use both +21v & -21v in
relation to 0v ??
Its the desk comp/limiter channel from the 189 series
Many Thanks,
Marty.

 

[MartyMart]

BUMP !
Looks like it is indeed a -21v dc supply going by the schem and some cap orientations,
why on earth would this be the case ??
Marty.

 

[Rob Flinn]

[quote author="MartyMart"]BUMP !
Looks like it is indeed a -21v dc supply going by the schem and some cap orientations,
why on earth would this be the case ??
Marty.[/quote]

It may use germanium transistors perhaps. The germanium Neve stuff uses a negative PSU. Mainly because PNP transistors are more common in germanium I think.

 

[Nele]

hmm.. it uses the MC1539 opamps and I would say an equal amount of NPN and PNP transistors.

NPN
BSX20, BC107A, BC109C

PNP
BC177A, BC179B, BCY 67.

Maybe some of the other Studer modules used PNP Germanium transistors?

 

[Guest]

Hi!

What compressormodule are we talking about?
If you mean 1.091.070 then, yes it recives a -22Vdc on pin 33.
This voltage is then devided to 2x -10.5Vdc in the module.
(There is a small regulator circuit after pin 33)
The schematic for 1.091.070 is located on page 284 in the service manual.
This module was used in the 089, 189 and 289 consoles.

Nele: Where do you see MC1539 ops? The 1.091.070 uses TDA1034 and A101 (DOA).

 

[Nele]

ah yes, but that's for rev. 4 (check bottom right) and from serial number 430. I have serial 280 and it uses the MC 1539 G instead of the TDA 1034A. I also have the schematic (rev. 1) for it but only on paper.

cheers,
corneel

 

[Guest]

Oh, sorry. My bad.

 

[MartyMart]

Still unclear from the Studer PDF, in technical Data page it says under "Power supply" 20.5 to 22v stabilised DC voltage and 180mA
Next page, under "Servicing instructions" it says power supply -21 V Stab !!
and has test points listed as -10.5v .....

Merry christmas

MM.

 

[Nele]

I'm pretty certain it's -21V DC. A bit confusing etc., but this is the way to go.
Tested the transformers on mine and they are still working.
One meter is out. There are no electrolytics on my board, only tantalums.. I guess I should replace those?

Merry X-Mas,
Corneel

 

[lolonweb]

Hi.

Can someone send me 1.091.070 schematics. I found some on studer  website but it is poor quality scann and many references can't be read.
I have two opf this comp and and i have strange noise on during the realise (frequency moving down)
is it normal?
Do you know someone who can fix this unit ?
Thanks
And yes, it is -21 v but you already know

 

[zamproject]

Hi lolon

Welcome to GDIY

I think you have to go with the pdf version for the schematic
It's a lovely PWM comp, have 5 (stereo) of them, 4 loaded in my 289
I know them well, and I refurb /restore/recap all of them.
But it's a pain to do (almost half a day to recap 6 lythic...) you have to remove lot of mecanical part, including trafo, and high frequency section mumetal cage  to acces solder joint 
It's an over bussy double-sided PCB, with component at both side, even two component layer at one side in some place...
Hate to service them... and by the way I'm out of TDA1034 in TO99 package, price is prohibitive now, have to manufacture an adaptor for NE5534

Best
Zam