RFZ V742dy
« on: May 13, 2020, 08:54:27 AM »
Hello everyone, I hope your collective wisdom could help me with a couple of RFZ V742dy isolation/line amps I have:

I got a pair of these cheap, allured by the split transformer balanced outputs, and to see if I could use it for general utilities at least/modification to the input transformer for greater gain at best (?). I understand the +24v referenced to ground and 0v to '-24v', so I have them working, that's all fine (I have V781s also). But I am a bit confused by them both.

Firstly, the main Leitungs Ausgang (line output) works OK, but that's about the extent of it's use.. the problems are as follows:

- Main line out DOES work, but with what sounds like a fixed HPF at around 200hz or thereabouts.. (both units behave same)

- Secondary output DOES NOT work despite being connected on those pins from the internal view, and I have checked the switch, seems to be fine (both units behave similarly)

- Abhörausgang (monitor output) DOES NOT work despite being connected on those pins from the internal view (both units behave similarly)

- I have recapped one of the amplifier PCBs, had replaced C4 (separate to the amp pcb) from a 25v 220uf Frolyt axial to a 63v 220uf Nichicon radial and it exploded after 20 mins! Why could that be?

I would really appreciate some help to get the splits functioning, otherwise I will gut it and use the transformers for something (open to suggestions..)

Some docs attached


Re: RFZ V742dy
« Reply #1 on: May 13, 2020, 08:56:04 AM »
Scheme 2

mjrippe

Re: RFZ V742dy
« Reply #2 on: May 14, 2020, 12:32:47 AM »
I replied to your identical post in The Lab  ;)


 

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