Hi,

I bought a 30W amp on Ebay which was supposed to be working but there is no sound out when I put a Shure mic into the input jack.

I found that although the mains on/off switch neon was illuminated, the mains input fuse was blown - which I then replaced.

All I hear now is a clunk from the speaker when I turn the mains on/off switch on, or off.

I have checked the AC out of the mains input transformer and also the DC out of the diode bridge which both seem ok.

I have replaced both the 2n3055 power output transistors and checked all the circuit board diodes - which seem ok.

I haven't been able to find a circuit diagram for the Amp, so I am a bit stuck now.

My next course of action was to desolder each component in turn and check them.

I would appreciate any help anyone is able to offer if maybe someone has had this problem before, or if anyone has the circuit diagram ?

Many Thanks,

Derek, July 2013

Hi, I have one of these and replaced both ICs. TL072. Works now.

Richard, June 2022