Help needed - AEG / Telefunken V776 disaster

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Dusty Circuit

Well-known member
Joined
Dec 23, 2008
Messages
81
Location
Sweden
Hi there,

A friend called me about three years ago and wondered if I could have a look at his racked V776 that was misbehaving. I accepted and when I lifted the lid I was greeted with this:

V776_1.jpg

V776_2.jpg

V776_3.jpg

V776_4.jpg

V776_5.jpg

Note: Gray is output from V776, Blue and yellow is input to V776.

V776_8.jpg

V776_9.jpg

Note: I added the brass spacers.

V776_13.jpg

The company that had sold him the unit had apparently fastened the input and output transformer PCB's with cable binding posts...... The wiring was also pretty sketchy so I decided to redo everything and mount the transformers on a new PCB with proper fastening and a bit tidier cabling. I also noted that one of the transformers had cracks in several places and was probably going to need a replacement.

A short while after this I got sick and had to put my life on pause for a couple of years.

Now it is time to get going with this again but I am having some trouble figuring out what the company that racked the thing was thinking.

The unit uses four Haufe RK255 as input transformers and four Haufe RK173 for the output. I am guessing that the boards the transformers are mounted to are from another type of gear, hence the messy bodge job. The resistors are 10k and the cap is a 470µF and connected on the output transformer secondary. I have tried to find this configuration on the output side on other AEG/Telefunken gear but have not found anything yet. I am a bit mystified by this and hope that maybe one of you have an idea of how this works. I can trace out a schematic if that would help.

Datasheets for transformers and schematic below:
RK173

EDIT: Added some notes to picture
 

Attachments

  • V776_15.jpg
    V776_15.jpg
    5.3 MB
  • RK255-1_Data.pdf
    70.5 KB
  • Telefunken_V_776_schematics.pdf
    372 KB
Last edited:
I was wrong in my previous post. The cap is connected on the primary of the output transformer. It was difficult to see.

I think this is right. The numbers on the transformer do not match real life tho.

Is this perhaps just an attenuator? Are there supposed to be a different set of transformers in the original design?

Schematic_Output.PNG
 

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