Searching for infos/schematics about Siemens console (811605)

[thekid777]

The power one psu is very nice (and very huge)

 

[thekid777]

 

[isophase]

well, isn't the supply supposed to be symmetrical +/- 24VDC ? this must be it since the negative side went in smoke ?

 

[isophase]

take a look a the circuit and check the polarity of some of the electrolytic capacitors for some hints?

 

[isophase]

bare in mind i am not an expert ! so you might as well wait until some "experienced" forum member prove me wrong or give his advices on the subject, good luck! i love your console !

 

[analogguru]

I had such a console, I think I sold it approx in 1992.  As far as I remember I also had only the block diagram, must have a look in my archive.

The console is from approx the same era as the one shown in the link below so I think the topology could be similar to it:

http://www.wsw.cz/index1.htm

BTW, in the late 70´s and early 80´s I worked with such a console (from the link) in the studio.  The best of it were those meters - I still have them :

The console was running on 24V DC - maybe the additional 24V is for the 48V Phantom-power (24V+24V = 48V).

analogguru

 

[thekid777]

Thanks analogguru
These vu-meter looks pretty nice
Just received complete book from Milan, thanks!!!
and docs of the console from Franz, thanks!!!
It works well now with 2X24V
I'm recapping all the channels now and will do the whole console.
Best regards

 

[isophase]

well done thekid777,
can't believe you found all the documents i'm so jealous!
so does it need two seperate +24VDC PSU or a split voltage with common 0V? or +/- 24VDC ?
good luck !

 

[thekid777]

Hey it's 2 x 24V with common ground.
It's super to see people can really help you here!
Thanks to this forum!

 

[thekid777]

I attached a schematic of the channel,
R4 is adjustable and I would like to know how I have to adjust it?
I don't know what's the use of it.
Thanks

 

[thekid777]

BumP

 

[Jean Clochet]

R4 is adjustable and I would like to know how I have to adjust it?
I don't know what's the use of it.

It's for setting the bias on the transistor.  Use the voltages given on the schematic as a guide.  So, trim R4 until you get 17.3V on Ts1 collector, or 17.9V on Ts2 emitter, or 10V on Ts3 emitter...

 

[thekid777]

Nice! thank you!

 

[thekid777]

When I trim to get 11V on TS1 emmiter I get 17,62V on the TS1 collector (instead 17,3)  18,18V on TS2 emitter (instead 17,9) and 9.96V on the TS3 emitter (instead 10) , I can't get all the values right whatever I do.
It's still acceptable? I don't know which V is the most important to get precisely right. thanks

 

[Jean Clochet]

It's still acceptable? I don't know which V is the most important to get precisely right. thanks

What you have there is fine, as long as it's in the right ballpark as the schematic you're OK.
What is listed is just a guide, tolerance of parts used etc. would hardly ever enable you to get exactly repeatable results with the schematic.
I suppose I might put the gain in the 'O' position myself while doing this. 
One more thing, what's the voltage feeding the stage you're measuring?  It says 18V on the doc. but I'm guessing it's a tiny bit higher.  Not that it really matters

 

[thekid777]

The voltage running the channel is 20V
Will try with 0 position gain

 

[Jean Clochet]

The voltage running the channel is 20V
Will try with 0 position gain

OK thanks for satisfying my curiosity.  Again,  you're just fine where you are so don't worry too much about being exactly the same as the schematic. 
If you come across a channel that you need to pick one transistor voltage to be the one to zone in on, then pick the emitter of Ts3 and make it half the supply voltage.  Just as your 9.96V is in relation to the 20V supply.

It's a nice desk by the way

 

[thekid777]

Thanks for the tip
Yeah! can't wait to hear it!

 

[thekid777]

Well, tested some recapped channels and I think it sounds nice!
I saw that the design is somewhat similar to the venerable 1073, do you see that?? (maybe it's a myth...)

 

[Jean Clochet]

it sounds nice!

That's good.

I saw that the design is somewhat similar to the venerable 1073, do you see that?? (maybe it's a myth...)

I can't comment myself on anything other than the input stage bit that you posted as I've never seen the schematic before.  I guess it's probably just typical of the technology used at the time on pro equipments.  Uncomplicated, single-sided stages.  I bet the eq is simple and musical - baxendall treble and bass and an inductor mid?  Possibly the transformers used here would be less coloured in sound than Neve but I don't know...  Also less colour because there are less caps involved and no tantalums?

You say it sounds good and that's what matters.