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Old peavy has no power

#21
I used to own that same model, and I have worked on MANY Peavey amps over the years. IIR that model uses a triac in the power on circuit. Check to see if the amp has the correct fuse, and if you have a meter check for line voltage on the PT primary.
 
#22
Systolic said:
As the the "Parts Guy" for one of the largest parts vendors in the country, i talk to a lot of techs and repair shops, and we go through a boat load of transformers on peaveys (older and newer.) I'm not saying that's what is wrong with the unit, but I will refute the idea that transformers don't go bad often.
Click to expand...

I've seen many techs replace transformers-------many did not need to be replaced.

Transformers fail, but I would put them low on the list.
Most failures are open----- no output. Or shorted---- blows fuse.
Rarely I between.
 
#26
Make sure you repair it in a room with a wet ceramic tile floor, and keep your feet on the ground with no shoes on. Don't use any insulated tools, and be sure they aren't made from plastic or graphite. Preferably, the outlet you're keeping the amp plugged into while you're working on it does NOT have a GFCI. Be sure that any little bits of steel or solder fall onto the circuit board while you're working and breathe in as many of the fumes as possible. You'll be fine, it's a Peavey.
 
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#28
jaybones said:
And let it sit for a day before opening it up. There are capacitors in there (think very high powered batteries) that have enough juice in them to fry a human being in short order. By letting it sit unplugged for a day, the charge they hold will dissipate.
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OMG!! That's scary...how many casualties are reported annually as a result of this?
 
#29
There aren't any capacitors on the incoming 120VAC side that hold a charge like this. The power supply filter caps are on the rectified secondary side of the power transformer, so to replace the power switch in this amp doesn't require the caps to be bled off.

Solid state amps work at much lower voltages than tube amps, so there's less likelihood of life-threatening injury from the energy stored in power supply filter caps. They should still be bled off if working on the amp's DC voltage rails. Note that some amps have resistors that bleed off the power supply caps, others don't. When working on the secondary side of the power transformer, we merely hook a bleed resistor in place and in a minute or so we can be assured the power supply filter caps are bled off, allowing us to work safely.
 
#31
jaybones said:
And let it sit for a day before opening it up. There are capacitors in there (think very high powered batteries) that have enough juice in them to fry a human being in short order. By letting it sit unplugged for a day, the charge they hold will dissipate.
Click to expand...

This applies to a tube amp more than a SS one. As SS devices conduct as long as they have power they will effectively drain the supply caps.

While on the subject of supply caps, never drain them by shorting them. A fairly low value resistor, say 1KΩ, will drain them quickly and safely.
 

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