Phase Linear 4000 repair help

[bcrescen]

I have a Phase Linear 4000 Series Two preamplifier where I only get sound from the left channel. Same result if I use phono or aux input. I do get sound from both channels when I use the headphone jack.

Any trouble shooting suggestions?

Thanks
Bruce

 

[poynton]

Hi

I have the circuit for the 3300.

It has a muting circuit on the output which effectively shorts the outputs.

Possibly the same circuit is used in the 4000 in which case trace back from the RH output and remove the muting transistor(s). in the 3300, they are MPSA16, Q103/203.

They mute the output at switch-on to prevent thumps.

Andy

 

[bcrescen]

Thanks Andy.

I traced the problem to a reed relay. I bypassed the relay and now get output from both channels. It sounds pretty good but I need to do a side by side with my old Hafler DH 101.

Bruce