Studer 900 - Racking

[saint gillis]

Ok I have put an external -24V, itdid not remove the hum.
  And it is exactly the same behaviour on both channels..

 

[saint gillis]

I was wondering... I ve connected the "screens" (on the mic input P6-16 and on the line input P6-6) to the ground through the chassis ground, do you think it is a mistake? I ll try to remove them from the ground

 

[saint gillis]

Ok I have found the problem!
  This circuit doesn't like when the voltages come from the same transformer

So I've added two small xformers for -24V and -6V, I've grounded the PSU as in the JML Powerplant, it's works perfectly, hope it helps..

 

[andre tchmil]

Struggling to rack a 900 strip also.

Current draw is spot on the same as per saint gillis measurements. ( well actually it's half of that since I only have one channel)

I have 3 separate psu's as well, all grounds connected to each other
Everything seems to work like it should be, except when I activate the low pass filter I get hum, weird not with the Hi pass filter.
The more I cut with the LP, hum increases. Can't put a value on it , but  enough to annoy me somehow.
Also I have a small thump  when I switch phase.
IC 113 in or removed doesn't change anything.

 

[andre tchmil]

Problem solved !
my -24v supply was actually -21v under load.
Weird, I thought this supply was  for signalisation only.

 

[Whoops]

Hello fellow members.
I have at the moment a Studer 900 Mono input channel strip on my bench to fix.
I did 3 Separate PSUs each with it's own power transformer to Supply the channel strip requirements.

All the PSUs are putting out the the correct voltages as in the Diagram attached, each PSU has 1Amp ou more available.

Connected the Mic input to "Mic Analog input" P6 a,b and screen
Connected Channel Audio out to the Pre Fader Send, it's and unbalanced send after the EQ section and before the fader, P6 27

I don't know if I should connect 0V INT and 0V Reference to the PSU 0V

After all the connections were made no LEDs light up on the module and I don't have a signal out (the audio out I'm connecting to a Line input of a small mixer and listening on headphones, also used a signal probe)

Could you kind souls please check the photo diagram attached and check if I'm doing something wrong or advise on how to do this properly.
I wrote all the voltage supply connections and audio connections I did

Thank you so much

 

[Whoops]

here is the photo with the connection made

 

[saint gillis]

  Hello!
You don't need to supply P3  connector, put your psu voltages only in P4 (put nothing in P3) and connect ground as you did in P6-26 & P6-28
You also need to link P6-29 and P6-30
Put 0V REF to your PSU ground (P4-25) don't connect P6-23

  Once you switch it on check your voltages with the channel strip supplied... normally you should had at least the filters leds on when you switch the filters on...

  Good luck, keep us informed

 

[andre tchmil]

make sure you j-have actually 24V under load.
That's what I  learned

 

[Whoops]

Thanks guys,
I will do as you advised.

I will go to the shop in the next days and will try it out and report back to you.

By the way I found 2 suppliers that have the connectors for sale, one has just the females and the other has both females and males:

Females
Small
https://www.vintagetools.de/Other/Connectors-Accessoirs/Studer-connector-small.html
Big
https://www.vintagetools.de/Other/Connectors-Accessoirs/Studer-64-pin-connector-900-series.html

Audio House in Switzerland has both the Female and the Male connectors (big and small) prices are around 15 euros each
http://www.audiohouse.ch/index.html

Thanks for your help
Best Regards

 

[zamproject]

By the way I found 2 suppliers that have the connectors for sale

Hi
It's standard din 41612, you can find way cheaper price for this... for sure if you put the Studer label on it the bill is x4  :
it's just a connector
best
Zam

 

[Whoops]

By the way I found 2 suppliers that have the connectors for sale

Hi
It's standard din 41612, you can find way cheaper price for this... for sure if you put the Studer label on it the bill is x4  :
it's just a connector
best
Zam

Hi,
what a rookie mistake LOLOL

I should have asked around here.
I actually search around the web to see if the connector used in the Studer desk was a standard one, but it was a dead end, only found those 2 shops.

So Din 41612 now I know, I can buy it from mouser or from farnell for much cheaper, although farnell doesn't have the 16 pin connector and mouser for the 16 pin only has the male version.

Maybe I can even find them locally
I just want to build a card extension , so I can connect a channel strip to the console but test it outside.

thank you so much Zam

 

[zamproject]

If you are in EU look at Reichelt and RS too, they have some
Regarding extender, also look at vero protoboard, there is some eurocard standard version available with footprint for 41612
Best
Zam

 

[Whoops]

Regarding extender, also look at vero protoboard, there is some eurocard standard version available with footprint for 41612

thanks, but can you please elaborate?

I just need to do an extender with female on 1 side cables connecting to a male on the other side, just that.

How could I use the Vero Protoboard for this ?

thank you

 

[zamproject]

to build something like this
http://fr.rs-online.com/web/p/plaques-dextensions-et-adaptateurs

It might be little more practical to have rigid part for connection at the frame side/bus board, access is tight with only one module removed.
You can keep flexible at module side so the module can just be perpendicularly laid on top of other modules

Best
Zam

 

[Whoops]

to build something like this
http://fr.rs-online.com/web/p/plaques-dextensions-et-adaptateurs

It might be little more practical to have rigid part for connection at the frame side/bus board, access is tight with only one module removed.
You can keep flexible at module side so the module can just be perpendicularly laid on top of other modules

Best
Zam

Thanks Zam,
But it's fine in this situation, I just need Fexible wire between both ends , 1m

 

[Whoops]

Have my Swiss approved multi PSU ready.

Troubleshoot will start!!!

 

[Whoops]

Did all the connections as advised. Module fired up.

Tape input works

Line input there's no sound at the putput

Mic in, the output spind is thin and really low in level
Started in troubleshooting Mic input, it seems the problem is somewhere in the small mic amp card, theres some bad contact or connection in the 10 pins that connect this board to the channel strip main card, if I put it with the pins in middle way to the connectors it works as it should, but in the normal card position with all the pins full inside the connector the sound is bad. Will chrck it better today

 

[Whoops]

Fixed the module,
there were some bad connection/contacts to the Mic Pre board and also in the shielded signal cables that run paralel to the connectors.
All is good now.

Thanks a lot for your help, actually it was quite easy to do, a lot of work to setup the 3 different PSU's and troubleshoot but easy fix in the end.

I will leave the updated stand alone wiring of the channel strip in case anyone need it in the future.

 

[saint gillis]

Good news!
  I don't know how many chanels you wanna feed with your psu, but for your information you can use a very small transformer for  -24V (and even for 6V)

For one chanel (being generous) :

+15V -> 100mA
-15V -> 100mA
-6V -> 100mA
-24V -> 5mA