Peavey TKO 80 bass amp cut out for a couple of minutes...

DartmoorHedgehog

My band's trusty old Peavey TKO 80 backup bass amp has been giving stalwart service for years, living up to its unkillable reputation.

That is until a recent gig...

Bass player's normal amp was in for repair so he was using the Peavey.  In the middle of a song it cut out - lights off as if the mains plug had been pulled out.  Fiddling with it, trying a different mains lead (it's converted to use a kettle/IEC lead) etc failed so he borrowed an amp from another band.

By the end of our set we noticed the Peavey had come back to life.

It's not worth much of course, but extremely useful (if it's reliable, as it has been up until that point)

Do any of the amp techy people know if there's any known area to look with these?  Does it have some sort of thermal cutout sensor? (it was a very hot cramped area in the corner of a small pub so the amp was up against a sofa and possibly hotter than normal, so if it's that then there may be nothing wrong)

ICBM

It could well be that - there is a thermal cutout.

I've also had a few with faulty power switches, the type used isn't quite beefy enough for the job really.

Funkfingers

Beaten to the punch.

Peavey solid state amplification often had protection circuitry built-in. I do not pretend to know - let alone remember - what was being protected.

The thermal issues guess is a good one. Loudspeaker preservation might be another. 

DJH83004

Been quite a while since I worked on one but from memory there is a thermal cutout embedded in the primary winding of the mains transformer and I think there is one mounted on the heatsink, suspect it was a thermal issue, especially if it came back to life under its steam.  

ICBM

Funkfingers said:

Peavey solid state amplification often had protection circuitry built-in. I do not pretend to know - let alone remember - what was being protected.

It's a straightforward mains primary cutout, in series with the power switch and the fuse, mounted on the main heatsink - so if it trips the entire amp shuts down. Simple but effective, and one of the reasons they're so hard to kill.

DartmoorHedgehog

Thanks folks - sounds like it may well have just got too warm then.  If so, that's good.  We'll give it a test at a band practice and if it behaves at "normal" temperature then it can be deemed still good as a backup.  It was extremely hot in that pub, and we were crammed in a tiny space with amps on top of each other.