Session 400 Hum Help?

[Bob Snelgrove]

Original Session 400, humming with no input, vol or tone controls don't affect it. Reverb is also out but probably not related.

My wife is good soldering and if there is a common fix (filter caps), Where would be a good place to start and source for parts?

Amp sounds fine except the hum but does "pop" when turned off.

thx

bob

[Tucker Jackson]

Reverb is also out but probably not related.

Make sure the reverb knob is turned all the way down if the pan is out -- and even if it's not out (just to test the connection).

That's all I got...

[Bob Snelgrove]

Reverb is also out but probably not related.

Make sure the reverb knob is turned all the way down if the pan is out -- and even if it's not out (just to test the connection).

That's all I got...

So, yes the reverb is down but if I turn it up it adds a different layer of hum, not the 60 hz constant hum

bob

[Dennis Detweiler]

Mouser Electronics would have the filter caps that you need.
Make sure your wife drains the existing filter caps before removing them. Or, not if she wants her hair curled?

[Bill A. Moore]

I would pay more attention to the line voltage in the SS Peaveys than worry about the low voltage/low amperage power supply filter caps!

[Bob Snelgrove]

I would pay more attention to the line voltage in the SS Peaveys than worry about the low voltage/low amperage power supply filter caps!

Meaning they are sensitive to low ac voltage, less than 120V?

bob

[Bill A. Moore]

Line voltage can deliver a shock, and has enough current available to be dangerous. You may get a tingle from the low voltage/amperage Power Supply, but not too much to be concerned with!

[Clyde Mattocks]

Not exactly a hum but a low frequency oscillation if I turned the volume above 3 or 4. I had tried cleaning the pots and all the connectors to the circuit board. I pulled out the speaker inputs and the amp inputs and reseated them and noticed some improvement. This amp had been sitting in an outbulding for some time. I started reseating the controls on the amp face and when I reseated the bass control, the oscillation disappeared.

I have quietened down several Session 400s by simply cleaning the pots and board connections and occasionally by rerouting wires in the chassis.