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Author Topic: Telefunken V72 output problem  (Read 3134 times)

industrial arts

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Telefunken V72 output problem
« on: August 08, 2013, 01:27:01 PM »

I have a couple of V72s on my bench for repair; the problem is low output.  I have traced the signal up to the output transformer but see nothing on the secondary side.  The secondary measures 10 ohms on both.  Seems a little low for an audio output secondary but since they measure the same, my first impression would be that the transformers are not bad.

I have disconnected the output transformers to make sure that there wasn't any problem with the wiring, so again it looks like 2 bad output xformers, but that just seems a little odd.
I have checked and double checked the units but with them both exhibiting the same problem (even though they are different vintages - besides the low output problem one of them has bad filter caps which appear to be older) I feel that I must be missing something.

My only other suspicion is that someone may have inadvertently plugged these into a hot phantom mic input and that's how both transformers got damaged in the same way, but that's just a wild guess.

I searched all over for bad or problems with V72 transformers, but have had no luck.

Any suggestions or advice would be appreciated.


Mark Springer
industrial arts


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Re: Telefunken V72 output problem
« Reply #1 on: October 07, 2013, 08:04:03 PM »

I'm here asking for V72 help myself. But I thought I'd at least ask what you mean by 'low output', because the V72 is not an especially high output pre-amp. And as what comes out is relative to what goes in, what is going in? If used with a low impedance mic with relatively high output, it should deliver a useful signal. As they both seem to be doing the same thing [as you noted] it makes me think they are OK and something else is wrong.
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