#1
Hey cool it's my first post ever.

Anyway, I have a Peavey Valveking 212 that I'm thinking may be the victim of a power surge. I turned it on the other day and got the tiniest flicker out of the indicator light, then nothing. No sound, no indicator light, no power to the tubes. I've triple-checked all the simple stuff, like different power outlets, making sure cables are plugged in, etc. I've replaced the main fuse (5a 250v ceramic, so I can't tell if it blew the fuse or not), and I checked the three fuses attached to the main board, all of which were intact.

Used a multimeter to check continuity on the power and standby switches, both passed. It can't be the tubes because that wouldn't prevent the unit from powering on at all, and it can't be the output transformer for the same reason, or so I am told. I guess maybe it's the power transformer?

I don't mind taking it to a professional, but I'd like to rule out being able to repair it myself first. I don't like spending money, and the turn-around-time for repairs is in the months right now. Any help is greatly appreciated.
#2
It could be the power transformer, heater wiring, any number of things really. If it was damaged by a surge, they will probably be an overheated component or two, look for brown spots on power resistors. If you aren't used to playing inside a valve amp you should take it to someone that is comfortable working on it. Inside a tubeamp can be a dangerous place, I wouldn't recommend you poking around in it.
#3
Thanks for the reply. Yeah, I'm just comfortable enough to test certain parts with a multimeter, but I know better than to go poking around those caps.

I looked pretty closely, and couldn't see any burnt out components, but obviously you can't always see them.

So it could be the power transformer? Those are pretty straightforward repairs, aren't they? Not that I'll be doing it, but I'll be relieved since I can probably have a power transformer installed for <$100.
#4
straightfoward, yes. but the power transformer alone will run you 100 bucks if not more.

To see if it really is the PT, you'd have to desolder it (or clip the leads off the board) and test it with an ohm meter and a volt meter.

Provided the amp was off during the surge then i dont see how it would make it past the power switch. a lightning strike is another story though.

and did you check the fuse? If there was a surge, theres a good chance it didnt make it past the fuse.
#5
He replaced the fuse without checking it. Though idk if he tested the new fuse to see if it is working.

TS http://www.geofex.com/ampdbug/nosound.htm Remember to bleed out the charge on the capacitors though. They can still hold a lethal voltage. This can be easily done. Take alligator clips and a 100k resistor, I'd use 1W power rating. Clip one lead from the resistor to the chassis with an alligator clip. Then connect the other lead to the anode of any preamp tube. You want the caps voltage to be done to about 10 volts or less preferably. This can be checked with a Analog volt meter. Available for ten bucks or less at a local hardware store if you don't have one.

http://www.aikenamps.com/SafetyTips.html
#6
Thanks for the help guys. After I test it all out and/or have it repaired I'll post results.
#7
You can very easily check to see if the PT is the problem with a multimeter. First, with nothing powered, use a multimeter to check continuity between the two PT primary leads. Then check continuity between the two secondary leads. You should get continuity with both tests. Now check continuity from 1 primary lead (doesn't matter which one) to 1 secondary lead (again, doesn't matter which one). There should NOT be continuity in this test.

If the above tests check out, then you can take some voltage readings. Set the multimeter to meter AC voltage and read the voltage to ground at the AC mains inlet to verify what's coming from the wall. Throw the power switch and meter 1 lead from the PT secondary where it meets the rectifier (AC to ground). Here you should be reading anywhere from around 275v-400v AC. If you're not getting any voltage here, you know the PT is shot. Switch the MM over to meter DC voltage and read the voltage after the rectifier. You should be getting anywhere from around 400v-600v DC. If you got a good reading before the rectifier but you didn't get a good reading after the rectifier, then the rectifier could be shot.

It's also a good idea to meter the AC voltage in the heater circuit. You can do this easily by metering the AC voltage to ground at pin 9 of any of your preamp tubes. You should get anywhere from 3v-3.5v AC on the meter. No voltage here also indicates a PT problem.