Input transformer for Auditronics PEQ-82 stereo eq

[API]

I am trying to determine what input transformer i have in a Auditronics PEQ-82 stereo eq i am trying to repair.
One of them is changed and not fitted very good so i was hoping to find the correct one.
It looks like a beige UTC but is unmarked, pinout seems a bit weird as well but it could have some connections cut of.

Anyone?

 

[plumsolly]

It is not a UTC as far as I know (did they make pcb-mount ouncers?). I have  one I could send you for the cost of shipping for a Christmas present, assuming they are the same ones as the older (pre Jensen) 110 channels. Strangely, if it is the same, it is a 1:8ish mic input transformer, so in that unit it should have ~40db pad in front of it - maybe 10k:150Ω. If you can confirm a pad like that, it is almost certainly the same. This topology (kind of) makes sense in a channel strip with both mic and line input so they can share a transformer. The only reason I could imagine you might do it in a line-level-only device is because you had a box of mic transformers already...

Best,

Ben

 

[API]

Hi Ben.

Thanks for the offer!
I will check if there is a pad in front of them over the weekend and will let you know.
Your theory sounds very likely though.

Regards,
Dennis

 

[API]

Hi again.

Just checked and there are a pair of 15k resistors in the input before the transformer.
Is that the same pad as in the inputmodules on the line in?

 

[plumsolly]

A pair of 15K resistors, huh? In series with each leg of the balanced input? On the 110, I think it is a 10k:62Ω L-pad. I guess your 15Ks form a U-pad with the resistance of the primary, but I would think a 30k+ impedance would make the frequency response of the  transformer all screwy? And then, assuming a 1:8 winding ratio, wouldn't that present an impedance of 64*30k≈2meg to opamp? I'm sure that's not right, but I definitely don't see what's happening. In any case, I bet it's the same transformer. PM me an address and I'll let you know what to send for shipping.

Best,

Ben