Valveking 100 watt head not working

[rednax]

My valveking's light doesn't turn on when I turn the switch on and the tubes don't glow. No sound comes out but it sounds like there's a buzzing coming from the power tubes. Would replacing the tubes fix the problem? I checked the fuse on the back and it's fine. Any help is appreciated.

[Jazz P Bass]

There are a number of internal fuses inside the amp.
One of them is for the heater/ pilot light.
If the fuse is bad, I would pull the output tubes & install a new fuse.
F 203: Time Delay 3 amp
If it holds, then you had a tube failure.

[rednax]

F203 was blown, is this the proper fuse? https://www.acehardware.com/departme.../fuses/3001559
I might try doing some mods while I have the amp apart. Will I have to replace any tubes and how can I test if the tubes are working properly. Thanks for the help.

[The Dude]

Yes. That is the right fuse. As Jazz said, replace the fuse, pull the tubes, and try the amp without tubes. If the fuse holds, you likely have a bad tube or tubes.

[g1]

Please make sure you have the amp back running 100% before you perform any mods.

[Jazz P Bass]

If the heater fuse (F203) is blown then you most likely had a tube that went south.
The tube may still be fine.
An internal short may have been vaporized.
Then again it may not have been.
You are asking how to 'test' the tubes.
Ok. Without a bevy of test instruments I would suggest that you simply replace the quad.

[Mick Bailey]

A tube tester that operates at the working voltage of an amp is an expensive piece of equipment and in most cases still won't tell you if a tube is bad due to microphonics or suffers from internal short or open circuits when vibrated (such as in a combo). Most people in the repair business do exactly what everyone else does - swap out a suspect tube with a new one or one that's known to be good.

[Helmholtz]

I don't have a schematic, but I doubt that F203 has anything to do with power tube heaters.

[g1]

I don't have a schematic, but I doubt that F203 has anything to do with power tube heaters.

Looks like all heaters sourced from there, pg.11 of attached schematic

[Helmholtz]

Looks like all heaters sourced from there, pg.11 of attached schematic

Thanks, seems I was wrong. Very unusual to use series DC heater supply for power tubes.

[Enzo]

Peavey started running preamp tubes on series DC quite a while ago, notably the 5150 series worked that way., and that design is 30 years old. I can be wrong but I think the Valve King was their first to run all the tubes - outputs included - in series. Cleverly, they used the same 900ma of the 6L6s and a parallel trio of 300ma 12AX7s on series with them.

They like many others had trouble with the high current of 6v heaters burning up Molex connectors between boards, so this limits tube current to under an amp.

[Richard]

There are a number of internal fuses inside the amp.
One of them is for the heater/ pilot light.
If the fuse is bad, I would pull the output tubes & install a new fuse.
F 203: Time Delay 3 amp
If it holds, then you had a tube failure.

It always amazes me when someone can diagnose a problem from a brief description. And 12 minutes after the original post! This is an amazing place.

[rednax]

I finally got around to fixing my amp, and was wondering what type of wire I should use to attach this fuse holder. The old connector for the fuse was stuck to the fuse so I decided I should just buy a better holder. I might try some mods once I get my amp working too. Any recommendations for easy mods?

[rednax]

I replaced the fuse and turned it on without the tubes and it died again. What else should I check?

[Jazz P Bass]

"What else should I check?"
The bridge rectifer may be shorted.
Check that.