phase linear series II model 4000 preamplifier need help!!

[stereosmith]

I picked up a phase linear series II model 4000 preamplifier and the left channel will not work. I have re-soldered the main board in hopes it was loose joints and also the balancer connections but nothing worked still no left channel. Does anyone know about these units or have an idea of what i could check? I would greatly appreciate it. thanks.

 

[century tek]

Aside from a possible bad OP AMP, check the RCA jacks themselves. My 3500 preamp is full of these, but they are all working. I also had to do the solder thing when I found mine and fortunately for me, that's all I had to do. If you have a signal tracer, you can find out where the signal stops and that is your problem. To a lesser extent, you can use a multimeter and compare readings from one side to the other.

 

[Jon_Logan]

Some preamps use muting relays. Sometimes they're wired to connect the signal to un-mute, sometimes they're wired as shunts to ground during the muting period. If they use a mute relay, maybe it's the type wired to connect the output and it's a bad relay?