Tube amp issues

  • Thread starter Thread starter shred_head
  • Start date Start date
shred_head said:
not too sure it that would be it, but on the back of my amp there is a reset switch.....would that be the auto bias option?


No. The reset switch is most likely for a circuit breaker in lieu of a fuse. On most/all amps there's nothing about biasing that you can get to from the outside of the amp. You need some specialized equipment to set the bias; most techs I know use a load box and an oscilloscope, but there are other ways. Biasing is not something that, in my opinion, you are ready to deal with yourself.
 
the problem with the controll most likely a coupling cap that's going bad and passing dc to the controll... but in any event time to see the doctor...
 
well ....talking again about what was happening with the main volume pot......

if you were looking at it with the knob side up....out of the 3 prongs
the first 2 left ones are connected using a 151 cap,

would have that cap being shot caused the problem?
there is no external damage that can be seen to it
 
shred_head said:
well ....talking again about what was happening with the main volume pot......

if you were looking at it with the knob side up....out of the 3 prongs
the first 2 left ones are connected using a 151 cap,

would have that cap being shot caused the problem?
there is no external damage that can be seen to it

What are you calling the main volume pot? Is it a master volume?

Anyway, the problem you are/were having may have absolutely nothing to do with the condition of the pot itself. The pot (assuming it's a master volume we are talking about) controls the signal going out of the preamp section into the power amp. The output of the preamp section could be the problem, or it could be the input to the power amp, or it could be something else entirely. It probably has nothing to do with that capacitor, at any rate. Have you looked at a schematic for the amp? Can you read a schematic? This stuff is a lot more complex than you seem to realize.

I know that it's frustrating, and you want to learn what is going on, but the odds of anything that you are doing fixing your problem, given the state of your apparent understanding of the electronics involved, are exceedingly low. Your chances of completely f**king it up and maybe getting hurt in the bargain, however, are pretty good. Your best bet is to get a good amp tech to fix your amp who will have the patience to sit down with you and explain what was wrong and what he did to fix it.

If you are really interested in learning how to service your own tube amps, the information is out there. It will take some study, and some long hours wrapping your mind around how all this stuff works. But you simply are not going to fix your amp by poking around inside it in total ignorance of the technology involved.

I hope I'm not being too harsh, and I don't want to discourage you, but amp techs who understand this stuff earn their money.
 
Yup I know.....I'm not going to touch the amp any more it is going to a tech in a few days

just curious of some things that's all


i don't have any schematics
and i searched for but couldn't find any

not even a manual for this amp

I just like knowing the shit,
I will ask the tech to sit in
I like this stuff


fun

especially when death is involved


"why is my arm numb?"
 
shred_head said:
Yup I know.....I'm not going to touch the amp any more it is going to a tech in a few days

just curious of some things that's all


i don't have any schematics
and i searched for but couldn't find any

Here are some places that have Randall schematics:

http://www.schematicconnection.com/store/asp/prodtype.asp?prodtype=153&ph=cat
http://www.one-electron.com/Randall/Randall_Info.html
http://www.musicparts.com/products.asp?Company=Randall
http://www.ampcrazy.com/web/schematics.html
 
been to all those sites before, with nothing for my amp,

but I contacted randall via email, and they emailed me the schematics and the original manual

very surprised it was so quick and that they got back to me at all,

very nice, thumbs up to randall for that
 
shred_head said:
been to all those sites before, with nothing for my amp,

but I contacted randall via email, and they emailed me the schematics and the original manual

very surprised it was so quick and that they got back to me at all,

very nice, thumbs up to randall for that

Cool. If the schematics are hard to find, your amp tech will appreciate that you have them.
 
ya.....save them the common problem of blowing the soles out of their shoes

had an uncle of mine moving a grain auger.....touched the power line, and blew his dentures out of his mouth, and his shoes melted,
other then the couple burn marks on his feet, he never been so....energetic?
 
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