Before you start ordering $30 reverb pans, take the pan out of the amp and look at all the connections for all of the wires. Some of the tiny coil wires are routed behind strips of metal and are susceptible to being chaffed and even cut.

About half of the used 80's era Peavey amps that I have owned have had problems inside the reverb tanks. It seems that the thin wires from the little coils pass through/behind a thin strip of brass to secure the wire as a strain relief. I've seen wires with their insulation worn through by that brass strip and I've seen wires almost pulled loose and just holding on to the solder point by their last strand. Might be worth looking at.

Are you using reverb when this is happening? Try turning the reverb knob down to 0. If the problem persists, try unplugging the plastic reverb wire connector on the bottom of the chassis.

Re: The HT50 label says 40 watts.  Made in China.  Eight inch speaker.  Solid state. 

It draws 40w from the wall.  Most likely a 15-20 watt amp.

The two speaker wires both absolutely must be soldered.  The blue speaker wire ( - neg ) goes to the pin closest to the front of the amp.  The yellow wire ( + pos ) is soldered to the pin closest to the rear of the amp.  Here is a link to the Studio Pro 40 operator's manual: http://peavey.com/assets/literature/manuals/studiopro40.pdf

Thanks.  Den.

I'm cleaning up an amp of mine and what appears to be white lithium grease was used between the two heatsinks and the back panel during the factory assembly.  I'd like to know exactly what kind of grease this is in case I need to renew it before reassembly of the chassis.

After having a look inside a Peavey Studio Pro 40 amp, I see that the speaker connections come directly off the circuit board.  I don't see an output transformer where a 4 ohm tap might be found.  My plan was to add a switching jack for an 8 ohm extension cabinet.  Am I missing something?  Is there a 4 ohm tap somewhere in there?