Roland SRA 540

[Carlosraj]

Hi,

I am trying to solve a problem that I am facing with this power amp. Both channels are working alright but there is a distinct buzzing sound from the second channel. Without any signal plugged in and with the volume totally off, there is still this buzz. It sound something like if a microphone cable shield is removed, you can hear a distinct buzzing sound. I checked to see if there is a break in the ground and shield connection, but it is intanct. This amp uses a single toroidal transformer, but separate rectifiers and filter caps for each channel. Can this buzz be coming from the power supply. Please advice.

Thanks

Carlos

 

[sgrossklass]

Sounds like a duff filter cap then. Got an ESR meter to verify? Otherwise you can solder a suitable 1000+ µF cap in parallel to see who the culprit is.

If that yields no result, you'll need to go on hunting for grounding issues...

 

[sgrossklass]

Oh, and make sure BTL/stereo switches and such fun stuff are working properly.

 

[Carlosraj]

Oh, and make sure BTL/stereo switches and such fun stuff are working properly.

Thanks alot sgrossklass. It was a filter cap. I replaced it and the amp is now OK.

Thanks again

Carlos