Siemens V276a + W295b input transformer replacements?

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adamasnan

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Sep 24, 2018
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Hi all - good and bad news. I got a whole Sitral console, but seems that many of the input transformers (about 4/8 W295b and 8/8 V276a) have shorted and/or failed.

I found a test subject transformer 1:1 for the 276a and they work with that..

So, I am gathering suggestions for replacements for these units. I think the w295b is something like a 4:1? (DCR p: 350 s: 80 approx) and the 276a I am not sure as I have none working well, so would appreciate if anyone has one and can share some info please. Jensen? Lundahl? Sowter? Other Haufe?

Thanks so much! more to come on this project for sure!
 
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David_H

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Not sure if you know this site DIY files but it has a lot of info on vintage German broadcast stuff, and among other things a section dedicated to transformers! If you're lucky, you might find data on your input trannies there!
 

mjrippe

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I am very curious about how so many transformers could be damaged. Was the console underwater or in a fire? I had several W295b from a burned console and some of them still worked!
 

adamasnan

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Sep 24, 2018
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I am very curious about how so many transformers could be damaged. Was the console underwater or in a fire? I had several W295b from a burned console and some of them still worked!
Yes, I also don't really understand. The rest of the console is actually quite clean, but there is a damp smell to it. It appears that the there is very heavy white/green deposits on the wires of the ip transformers. I can only assume they have corroded due to damp storage, or some kind of extended period of over voltage? Anyway, the rest of the circuits work it seems.. I just need some data on the transformers, or suggestions for alternatives!

Thanks!!
 

adamasnan

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Sep 24, 2018
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Not sure if you know this site DIY files but it has a lot of info on vintage German broadcast stuff, and among other things a section dedicated to transformers! If you're lucky, you might find data on your input trannies there!
Hi, yes am very familiar, thanks for sharing though. Sadly no relevant info there.
 

mjrippe

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Yes, I also don't really understand. The rest of the console is actually quite clean, but there is a damp smell to it. It appears that the there is very heavy white/green deposits on the wires of the ip transformers. I can only assume they have corroded due to damp storage, or some kind of extended period of over voltage? Anyway, the rest of the circuits work it seems.. I just need some data on the transformers, or suggestions for alternatives!

Thanks!!
Oh that is so sad! Very likely humidity or a flood caused this corrosion and damage. Sometimes "old" things are put in the basement where moisture can seep in and cause all sorts of problems. I'll see if I have any info on the transformers. Do you have any Siemens or Haufe part numbers?
 
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adamasnan

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Sep 24, 2018
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Oh that is so sad! Very likely humidity or a flood caused this corrosion and damage. Sometimes "old" things are put in the basement where moisture can seep in and cause all sorts of problems. I'll see if I have any info on the transformers. Do you have any Siemens or Haufe part numbers?
I know it is sad! But also, it's in such good cosmetic shape otherwise, all of those elusive black knob caps are present and intact at least! I'm slowly starting the process of restoring it.

Yes, I have the transformer numbers according to Siemens/Haufe

V276A : T 925 F
W295B : T 892 B
 

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mjrippe

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Damn, that is a beautiful piece of gear 😍 Unfortunately nothing in any of my files for those part numbers. The closest things I have here are W395 and V672 with totally different transformers. Hopefully someone here has the right units and can give you some measurements! Also, where are you located? The closer to Germany the better 😁
 

adamasnan

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Sep 24, 2018
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Damn, that is a beautiful piece of gear 😍 Unfortunately nothing in any of my files for those part numbers. The closest things I have here are W395 and V672 with totally different transformers. Hopefully someone here has the right units and can give you some measurements! Also, where are you located? The closer to Germany the better 😁
Thanks so much! Yes I am having trouble finding the specs for the 276a ip transformer. A call to Haufe is looking necessary but that doesn't give much hope either..

Luckily I am located in Berlin :)
 

Michael Tibes

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You
I just need some data on the transformers, or suggestions for alternatives!
But you do have some working transformers, don't you? You could measure these, which might help to find substitutions? Calling Haufe might be a good option too, maybe they can even still build new ones. I'm in Berlin too and have these modules in case you need working ones to measure.

Michael
 

adamasnan

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You

But you do have some working transformers, don't you? You could measure these, which might help to find substitutions? Calling Haufe might be a good option too, maybe they can even still build new ones. I'm in Berlin too and have these modules in case you need working ones to measure.

Michael
Hi Michael - sadly all of the ip transformers of the 8 (!) preamps are dead. So, I cannot measure any! It would be so kind and helpful if you could make/I come and make some measurements of the T 925 F you have?

Thanks so much!!
 
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adamasnan

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I had a reply from Haufe!

--

wir konnten das Bauteil bei uns identifizieren, es handelt sich um den Übertrager T 925.
Allerdings can wir diesen leider nicht mehr herstellen, da er Scheibenwicklungen hat, welche wir nicht mehr herstellen können.

Wir können Ihnen nur folgende Angaben (ohne Gewähr) zu dem Übertrager T925 mitteilen:

Übersetzungsverhältnis: 0,5 + 0,5 : 6
Primärwicklung 1: Anfang rot, Ende grün.
Primärwicklung 2: Anfang braun, Ende gelb.
Sekundärwicklung: Anfang blau, Ende weiß.
Gehäuseerde, Kernerde: gelb/schwarz.
Impedanz Primär: 2 x ca. 5 kOhm.
Impedanz Sekundär: ca. 1 MOhm.
Ohm’scher Widerstand Primär: 2 x ca. 15 Ohm.
Ohm’scher Widerstand Sekundär: ca. 690 Ohm.

Ich hoffe, das hilft Ihnen weiter.
 

TwentyTrees

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I had a reply from Haufe!

...
Google Translate version for those of us in the cheap seats:

"We were able to identify the component with us, it is the transformer T 925.
Unfortunately, we can no longer manufacture this because it has disc windings which we can no longer manufacture.

We can only provide you with the following information (without guarantee) about the T925 transformer:

Turn ratio: 0.5 + 0.5: 6
Primary winding 1: beginning red, end green.
Primary winding 2: beginning brown, end yellow.
Secondary winding: beginning blue, end white.
Housing earth, core earth: yellow / black.
Impedance primary: 2 x approx. 5 kOhm.
Secondary impedance: approx. 1 MOhm.
Ohmic resistance Primary: 2 x approx. 15 Ohm.
Secondary ohmic resistance: approx. 690 ohms.

I hope this helps you further."
 

Michael Tibes

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25 years ago I still bought new V76 input transformers from them. Seems like yesterday... I wonder if someone could rewind them in europe? I can imagine that a Lundahl transformer might deliver a similiar performance, but is there a model that fits mechanically?

Michael
 

adamasnan

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Sep 24, 2018
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I have tried a Haufe T4235, That I got 10 of, once the can is opened they fit in the T925 cans nicely. It's 22k prim and 88k sec, and a ratio of 1:2 is wired correctly.

The V276 works, but I am unsure of actually how it is supposed to sound. Right now, I think it sounds kind of muddy and not very sexy on either highs or lows. I also think the circuit really need a 1:6 otherwise the gain indications are off..

Michael! Would you be willing to temporarily lend/rent out a V276a so I can compare? I can let you borrow a Neumann PV76 if you want, I have 6 :) I would get a few few suitable transformers together and see which sounds the most similar I guess..

Thanks!
 

mjrippe

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Brooklyn, NY
Do we still have a private message system? I tried to send you a p.m., but I'm not sure if I did it right. I'm kinda always in a hurry these days...
Hold your cursor over the user's avatar (The big green "A" in this case) and a window will pop up. Select "Start conversation" for PM.
 

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