ARE MY TUBES FUCKED.

  • Thread starter Thread starter Baza
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Baza

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I'm gonna need some opinions here guys. I have a Fender pro-reverb amplifier and it is making some serios humming sounds even when the guitar is not in. The tubes are all black at the bottom (all of them). I think one off my output valves is reaully fucked because when i turn it on the whole thing i lights up blue inside.
I have already sent aqway for two new output valves and a driver valve. I don't know much about them I've heard that when you replace you're output valve you have to biass it. Could someone ploease tell me whar this is and how to do it without killing myself. I'd reaully appreciate some help with this as this is a good amp and idon't want to damage it. CHEERS!
 
Ummm, I think that there are some things best left to Amp techs. Get hold of you nearest (yet trusted) Fender dealer/tech shop and let them do the bias thing. Also, they will tell you if your amp is need of new tubes. This could be nothing more than a ground loop problem. The outlet or strip that your amp is plugged into may not be properly grounded or the phase is reversed (some amps have a ground switch which can reverse the phasing). Always good to check out the minor stuff. As for the tubes being black at the tips, this is fairly normal. I can't remember if the tube is supposed to glow blue or orange--its been about fifteen years since I owned one. I seem to remember my tubes would glow ???? Oooops, can't really remember.

Peace, Jim
 
Well I don't think your tubes are F#~*<*!

It soumds like you should take the new tubes
and amp to your local Tech and have them installed, and the anp biased. Let the Tech listen to the problem before the tubes are replaced. And by the way, spend a few more bucks and replace all the tubes
 
SSSHHH Your not supposed to swear in the forum topics or the forums

just the Dragon cave :D

Tony
 
yeah isnt there some sort of rule about swearing here?
Not A Good Idea!.
 
You see the problem is. Out where i live there are no descent fellas you cant take the amp to. There all just con men who don't have a clue, down here where i live. But i'll try and find someone.
And i'll try and cool the swaring.

keep the faith.
 
When tubes have a lot of blue this is a bad sign. It means the tube is gassy and is in need of replacement
 
Blue tubes will soon equal blew tubes....

Its time to replace those power tubes. Also don't worry about the black silvery looking stuff in the bottom of your tubes, if you you don't see that stuff, then you have a problem. Biasing the amp is a good thing to, but if you don't know how to do it and can't find a good tech then here is a simple solution. Amps need to be biased or matched to tube/valves of different ratings or qualities. For example Groove Tubes have a higher output than most other tubes and Ruby Tube's output is equal to most factory installed tubes. This doesn't mean that one is better than the other- just different. If you are replacing original or standard tubes with let's say Groove Tubes or any other higher output tubes like Mesa or some Sovtek tubes, then it is best to have the amp biased because these tube will cause your amp to have more gain. If you replace your exsiting standard tubes with Ruby tubes(which I highly recomend for a Fender amp)then you don't have any thing to worry about. Your amp could possibly stand to be biased if you are still not happy with the tone after replacing the power tubes. Also check you preamp tubes. They cuold be causing some of you noise problems, but based on what you are describing, I think that they are ok. Check them for any type of blue or green glow. If they are ok, they will glow orange/ yellow only. Now if you are into hands on.... it is possible to bias your amp at home. If turn amp upside down you may be able to see a small plastic dial near the power transformer(the big one). this is the bias adjustment. DON'T turn it until you have all of the info you need. Because your electrical suply in Europe is 50hz instead of 60hz like the U.S. I'm not sure if the proceedures are the same. Try to find a book called "The Tube Amp Book" this book has specs and scematics for almost every Fender amp made. The book also covers repair, troubleshooting, modifications and adjustments. Biasing an amp is not very difficult but if decide to service your amp on your own PLEASE BE CAREFUL!!!!! Tube amps opperate at HIGH VOLTAGES as high as 700 vac. They also have capacitors that store electrical energy even after your amp is turned off or unplugged. Hope that my rambling is of some help to you.....

[This message has been edited by Daddy-O (edited 06-11-2000).]
 
Cheers lads. That information was allot of help. I'll get back to yous if i have any more problems.
 
Baza,

If you lightly tap the tubes (with your fingernail) when the amp has been on for a few minutes, any tube that makes a clunky kind of sound (how about that for a technical description?) needs to be replaced.
You'll know the sound as soon as you hear it, and unless all of your tubes have recently had s----l i---------e, the bad ones will be very easy to spot.

I'd also like to repeat what Daddy-O said - BE CAREFUL, even when the amp is off - large amounts of energy are stored in tube amps.

foo
 
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