Hello Everyone,
While I am not a noob to DIY I am to building these CAPI V28's. I purchased 2 and put one together with 2 2520 op amps (kits) and then the fun began.... I have signal going in through the mic (both reg and condenser w/ 47v), signal Led lights up... and upon listening to the output... its a constant 60 cycle hum ( the knobs do not reduce or make it louder).... (although if I crank the gains you can slightly hear a distorted signal way in the background). I've tried swapping the 2520's, I've tried it without them... and swapped cards in different ports and working cards in those ports so I know the ports are good. I get the same hum.
I am awaiting more banana plugs to do further testing (published test points), but this is what I've tried so far....
Resoldered both amps and main PCB board
Traced back the output to the last of the transformers.
Without a schematic I cannot do anything more. I'm assuming since I have the hum with and without the op amps, that they are not an issue. I don't know if its a bad trace, bad part or what.
Any guidance would be very much appreciated.
Thank you in advance!!
Bill