Peavey Valveking VK100 died

[Spuris]

Hello everyone,

Just last week my Peavey VK100 MK1 died on me. I was playing in a rehearsal and it suddenly went silent. It didn't shut down and I noticed that the power amp tubes were looking weird. The two tubes to the left were really dim and the two on the right were really bright.

So I shut it down, changed the head to another one to continue the rehearsal and noticed that 2 of my pedals in the FX Loop (MXR Carbon Copy Deluxe and Akai Headrush V2) that were on at the moment when the amp died were not letting any signal through anymore. So it looks like the head took them with it. Could it be that somehow the FX Loop let some current through to the pedals that killed them?

I checked the tubes with the Orange VT1000 tester and all of the power tubes tested as "failed", same thing for the pre-amp tubes, only one tested as "worn", others failed. I have never come across all of the tubes going out at once.

I took the chassis out, checked it and there were no obvious visual signs of any damage or something burned. Tested all of the fuses, they were good.

I don't have any knowledge with amp repairs and diagnostics, but I am quite handy with soldering iron and have done some small repairs on amps and pedals, like replacing jacks and other obviously faulty components without any problems. Yes, I know that you can have high voltage stored inside the amp and that you need to discharge it.

I was hoping that someone can help me with the diagnostics of the fault and repair or at least point me in the right direction. I am always willing to learn.

Thanks!

[g1]

Maybe you just had a pedal problem. Not sure I would trust the tube tester, especially if you had no blown fuses.
Put the tubes back in the amp and try it with no pedals.

[TomCarlos]

And if you have another amp, test each pedal, one at a time, before the input jack. So guitar to pedal to input jack. I don't see how the amp would have damaged your pedals.

[Spuris]

Maybe you just had a pedal problem. Not sure I would trust the tube tester, especially if you had no blown fuses.
Put the tubes back in the amp and try it with no pedals.

Why wouldn't i trust the tube tester? I confirmed that it is working with good tubes. I already tried to check the amp without any pedals, still the same issue.

[Spuris]

And if you have another amp, test each pedal, one at a time, before the input jack. So guitar to pedal to input jack. I don't see how the amp would have damaged your pedals.

I tried the pedales one by one directly into another amp and confirmed that they were gone. I have a bunch of pedals in my pedalboard, and I use a pedal switcher in FX loop, these 2 particular pedals were the ones that were on on the switcher at the time when then amp went. That's a mistery to me.

Either way I was hoping to get the amp sorted at first and then deal with the pedals.

Any ideas on what to look for? I'm not really keen on putting new tubes in there to just blow them out again.

[Helmholtz]

Does the amp have the correct type/value mains fuse?

Is there a schematic?

[glebert]

This is how I would approach it. Find the appropriate schematic. With power tubes pulled (and observing safety practices) measure the voltages at the tube sockets. To me that will tell you how healthy the amp is. No idea why the pedals could have gone out, unless there was some sort of power spike that took out the amp and the pedals too.

[The Dude]

^^^^^^ That! If indeed the tubes are all bad, check voltages at the tube sockets before installing new tubes. That said, I don't recall EVER, in 40+ years, having an amp come in with every single tube bad. I have doubts about the tester or testing method myself. A fuse should have blown before all tubes were taken out, so also check that fuse(s) are the correct value.

[Helmholtz]

A fuse should have blown before all tubes were taken out, so also check that fuse(s) are the correct value.

That's what I thought (post #6).
Also I asked for the schematic to see what other fuses the amp has.

[TomCarlos]

No idea why the pedals could have gone out, unless there was some sort of power spike that took out the amp and the pedals too.

I was thinking the same thing as Glebert. One time, during a garage jam, a guy had his amp fry. An hour later, another guy had his amp fry. The problem was most likely due to high voltage on the outlet. If you lose a neutral wire in an electric circuit, that could put 240 volts on a 120 outlet. I told the homeowner to pull each outlet, check the wiring, look for loose connections, especially on the white (neutral) wires. And sure enough, one of the outlets in the garage had a hanging neutral. It was connecting intermittently and chances are, that is what caused the problem.

So in your case, the amp could have seen 240 volts. If you had a power supply powering the pedal boards, that too could have been subjected to high voltage.

Get yourself a cheapy AC voltage tester, something specific to measure home ac. Test each outlet that is on the same circuit breaker. Your problem could be originating in a different location.

[glebert]

So in your case, the amp could have seen 240 volts. If you had a power supply powering the pedal boards, that too could have been subjected to high voltage.

FWIW, looks like the OP is in Latvia, which should have 230V AC mains.

[TomCarlos]

FWIW, looks like the OP is in Latvia, which should have 230V AC mains.

Thanks for pointing that out.... But it could be a similar problem.... a wiring issue causing high voltage. I guess my reply should be consider USA compliant only!!

[Spuris]

Does the amp have the correct type/value mains fuse?

Is there a schematic?

Yes, the fuses are the correct ones.

I have attached the schematic here.