Having Trouble with my Tube Amp...

[atticus3897]

I have a Peavey Valveking 100w head, and I've been using it and everything has been fine, then I tried to turn it on today and the red light came on in the front when I flipped the power switch, but the tubes are not lighting up. I took the amp off of standby and no sound. I don't think it would be the tubes because I thought that they glowed bright red or blue if they were no good, and I'm just getting no lights whatever. Perhaps a VERY VERY dim light, dim enough to where it's barely noticeable.

I'm thinking it's not receiving all the power or something like that. Does anybody have an idea what might be wrong with it? or how to check to see what is wrong with it? Because I called a local authorized Peavey dealer and they want 52 bucks just to look at the damn thing.

Any help would be greatly appreciated.

[jonnyc]

Pull the fuses and make sure none are blown. Same thing happened to my Randall tube amp once and all it was, was a fuse.

[atticus3897]

ok i'm not too start with this stuff, what does the fuse look like so i know what to pull out? and how do i know if it's blown?

[arcaxis]

Below are pics of a fuse holder that might be on the back or on the chassis of the amp, sometimes near where the power cord is. The cap unscrews from the holder to access the fuse. Your amp may have it's fuse(s) located under the chassis which is more difficult to get to. The fuse has a wire inside from end to end. If the current in the circuit its protecting goes too high the wire burns out which opens the circuit to protect the power supply and other components. If you look through the glass of the fuse the wire may be gone and it may even look burned slightly on the glass inside.

Under the chassis are some capacitors that store high voltage. If you don't know what you're doing, don't go poking around under there - it could potentially kill you or really hurt like hell.

And a pic of a typical glass fuse used in the holder below.

The tube filaments may not glow real bright, but in a darkened room you may be able to see them and if left on for a while should feel warm to the touch.


Found the manual and downloaded it.....

Fuse appears to be on back of amp next to power cord, marked F5A ( 5 amp fuse). Cap should come off with a screw driver. Try powering up the amp if you get the fuse out. If the pilot light doesn't come on with the fuse out, the fuse is probably good and it's something else wrong such as another fuse that may not be easy to get at or something more serious.
If you do replace the fuse, get one that replaces it exactly. There different types meant for different types of protection.

In your manual is stated the Peavey warranty which for a minimum looks like 2 years if you bought it new.

[atticus3897]

i unscrewed the fuse from the back of the amp, then tried to turn it on and the red light did not come on, what should i do now? is it possible there are other fuses that could have blown?


the fuse is not clear though, its not dark, its just completely white and i cant see through, could this also mean it has blown or is it simply not a clear fuse?

[tom18222]

the amp wont turn on without the fuse in there you fucking asshole.

[arcaxis]

Originally Posted by tom18222

the amp wont turn on without the fuse in there you fucking asshole.

That was the idea. This sort of indicates the fuse he pulled is on the primary side of the power transformer and was not blown. With the fuse in the holder the pilot lamp comes on and a good chance the tube filaments will be lit indicating the power tranny might be OK. This sort of points to a problem possibly in the DC power section or beyond.

So how would you have tested that fuse with no test equipment and a fuse you couldn't see through Tom ??

Found a schematic this morning and looking at it there are (3) fuses mounted on a circuit board inside.
F201 - 1.5A SloBlo - High Voltage supply fuse (my guess if it's a blown fuse it's this one, but there's likely a reason it blew)
F202 - 1A Pigtail (soldered in) type fuse - Power tubes DC bias supply
F203 - 3.0A - Filament and Pilot Lamp DC supply (not blown)

Sorry atticus, it looks like it's time for a trip to the amp doctor.....hopefully under warranty.

If you're interested in the schematic here's where you can get it>
http://www.schematicheaven.com/post70s.htm

[atticus3897]

problem is, i can't afford to bring it to an amp specialist, im gonna have to do some shopping around for a good price, but thanks


ps, tom and i are friends, so he is just busting my balls

[atticus3897]

what kind of safety pre-cautions could i take so i could maybe do this on my own? perhaps heavy duty rubber gloves?

[ggunn]

Originally Posted by atticus3897

what kind of safety pre-cautions could i take so i could maybe do this on my own? perhaps heavy duty rubber gloves?

Um, no. If you don't have at least a good basic understanding of vacuum tube electronics, you should not attempt this on your own. Sorry, but you wouldn't try to take your appendix out yourself if you didn't want to pay a doctor, would you? In either case, you could die, and that's no exaggeration.

BTW, if it is one of those internal fuses, it's not very likely that the blown fuse is your only problem; something took out that fuse. Even if you did get the blown fuse replaced, it would probably just blow again. All the more reason to take it in.

[dementedchord]

oibviously you dont have the required skill set to work on this yourself... and when it's broke aint really a good time to start learning it...


as to looking for a deal on a tech... this comes under the heading of false economy... how much have you saved if the guy takes 2-3X's as long to fix it??? find a good tech and pay him what he's worth... if we keep this shit up no ones gonna want to be a tech and then where will ya be ??? buy ing a new amp because ya couldn't get anyone to fix it....

[gvarko]

Originally Posted by tom18222

the amp wont turn on without the fuse in there you fucking asshole.

Thanks for the information ....

[ggunn]

Originally Posted by gvarko

Thanks for the information you fucking douchebag ....

Originally Posted by atticus3897

ps, tom and i are friends, so he is just busting my balls

..........................

[atticus3897]

turns out the tubes got loose in transport, so i pushed em all back in and everything is back to normal

[arcaxis]

Originally Posted by atticus3897

turns out the tubes got loose in transport, so i pushed em all back in and everything is back to normal

Damn good thing it didn't go into the shop for 52 bucks of bench time
Glad you figured it out.......

[TelePaul]

Originally Posted by atticus3897

turns out the tubes got loose in transport, so i pushed em all back in and everything is back to normal

Wow! That was lucky! Good job.

[soundchaser59]

Originally Posted by atticus3897

turns out the tubes got loose in transport, so i pushed em all back in and everything is back to normal

Well, who transported it? FedEx? Or UPS?

I would think that's some pretty rough transport to make the tubes come loose out of their sockets. WOW! Either that or Peavey put some pretty darn scummy tube sockets in there....

[atticus3897]

no i have had it for a while now, i meant while i was transporting it from my practice place back to my room


i try to be very careful, ill just be a little more careful from now on

[TelePaul]

Originally Posted by atticus3897

no i have had it for a while now, i meant while i was transporting it from my practice place back to my room


i try to be very careful, ill just be a little more careful from now on

switch it on stand-by when you're done, let it power done for five minutes. Hot tubes are delicate!

[ggunn]

Originally Posted by TelePaul

switch it on stand-by when you're done, let it power done for five minutes. Hot tubes are delicate!

The tube heaters stay on in standby.

[TelePaul]

Originally Posted by ggunn

The tube heaters stay on in standby.

You're quite right ....well, put it on stand-by, switch it off, and dont move it right away.

[atticus3897]

yeah im really good about let it warm up for at least 5 minutes, and then i keep on standby for a while, and if i am transporting i usually let it sit for a few minutes before i unplug it etc


but thanks everyone for the help

[ggunn]

Originally Posted by TelePaul

You're quite right ....well, put it on stand-by, switch it off, and dont move it right away.

I never use the standby switch unless I'm letting the amp sit for a while powered up and I don't want it to make any noise, otherwise I just flip them both on and off together. I've been playing through tube amps for 40 years and never had any other need for standby. Some of my amps don't even have a standby switch.

[dementedchord]

ok... well then now might be agood time to learn alittle about tube amps after all...

one of these days unplug it after you're done and let it sit till morning... then pull the head out of the cab and pull all the tubes and lay them out in order so they all go back the same... now look down into the sockets and check out how they grab the pins of the tubes.... what ya want to do is close them up abit so they grab the tubes better... use a little (jewlers) screw driver to manipulate the tabs (i use dental picks)... while you're in there give it a good once over to visualy familiarize yourself with the parts (maybe take some pics for reference) so when you read some of these threads you know what we're talking about... glad it worked out for ya..