Amp hum...Broken tubes??

C

coolasvanillaic

New member
Hey,

Today when I turned on my Peavey 5150 there was a really loud hum and I coulnt figure out what it was. I checked all the cables and I have a feeling its the tubes. How would I know if the tubes are bad? The symptoms I have are very loud hum and very low signal.

If it is the tubes, how should I go about getting new ones...should I buy them and put them in myself? Also what tubes are good? Im assuming I should go and play amps with different tubes.

Any help would be great.

Thanks,

Matt
 
Ask around, find the name of a knowledgeable amp tech, and take it there. There's quite a lot going on in the 5150s, tube-wise, that I wouldn't want to get into if I wasn't confident in my skills and knowledge.
 
Make sure they are all seated properly, and are they warm after about 30 seconds. Sometimes they warm up, but aren't working right anyways.
 
While the amp is on, tap the tubes lightly with a pencil eraser. You should hear some click or pop when you do this, but if it is loud or there are any other sounds out of the ordinary the tube probably needs replacement.
 
No Fingers!!!

What ever you do don't touch the bare tubes with bare fingers. That's when cold of course. The oil from the fingers causes hot spots on the tubes where the electrons have a tendency to concentrate which can lead to arcing in the tube burning it out. I am told this by an older (60's) electronics tech.

The sockets and pins sometimes get a build up of residue from electrolysis and like said above sometimes removing then reseating them will help.

On some russian made hot rod tubes they will pop or click loud or have a reverb sound (ecohing sound) even if they are good. Best to check them out with a tube tester. A good tech shop should have 1. Remember which sockets the tubes come out of. Each have numbers usually on the side of the tubes.


:D
Good Luck
D
 
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