Peavey Combo low volume

[Prairie Dawg]

I've got one of those old Peavey bass amps called a Combo circa 1978 that I took on as a favor for a friend. It seems to be all there and nothing's burned or scorched, but the volume is pretty low.

Any thoughts before I essay a look around? Solid state is not my forte, but this amp seems about as uncomplicated as solid state can be. He bought it for a song and relates that the previous owner said that the volume would gradually drift downward until he parked it some years ago.

I'm thinking that maybe there's something changing value as it heats up?

Thanks all.

[bkahuna]

The first thing to check would be the sticky post at the top of this forum. Check that and let us know how it responds to those tests.
Good luck!

[Prairie Dawg]

Worth a look see for sure and I just printed it out. I've got to figure this thing out.

[Jazz P Bass]

Peavey Combo.
Is there not a number after that?
150 or 300?

[Prairie Dawg]

The panel says Bass Combo Mark III series, and the data plate on the back of hte cabinet says 115 B.W. Combo.

It is allegedly rated at 150w.

[Jazz P Bass]

150 watts into 4ohms should be about 25Vac max at the output.
What do you measure?

[52 Bill]

If this is like the one I remember, it doesn't have pre/power in/out jacks, but the preamp output jack will kill the signal to the internal power amp if a plug is inserted all the way in.

Clean this jack first thing. If that doesn't work, then it's time to open it up.

[Prairie Dawg]

Got to the bottom of it this day. I had it on the bench and it sounded a lot better through my shop 12" Celestion. The friend who it belonged to brought a bass over to put the right kind of signal thru it and then we ran it through a 4x8 cabinet I have.

The voice coil was seized up and jammed in the fifteen inch Black Widow speaker. I had some fun while I was inside it though. Occam's Razor says never ignore the obvious solution.