ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Tube Amp - DEAD

:

5/19/2000 5:35 AM

Tube Amp - DEAD

Hi,
We use a Marshall Tube amp to jam on. Before
it was squealing if you set the dirty channels
gain up to high with the volume cranked, and
also if you just litely touched the strings a
weird hiss could be heard. Anyways I suddenly stopped playing the guitar (handmuted) and I heard some small Pops. No guitar coming through any more. It is definately the amp as the guitar worked on the bass amp using the same gear.
All the tubes have a orange glow and the glass casings are a little black. Are they meant to glow orange or not? The reverb doesn't work on the amp also which I think is tueb driven as well.
There are two large tubes and three small ones.
Thanks

5/19/2000 9:21 AM
Max	Hi Black! All the tubes have a orange glow and the glass casings are a little black. Are they meant to glow orange or not? No definitely not!time to rebias,or,even better bring the amp to a tech! Best regards. Max.

5/19/2000 12:53 PM

quote:
"All the tubes have a orange glow and the glass casings are a little black. Are they meant to glow orange or not?

No definitely not!time to rebias,or,even better bring the amp to a tech!"

There should be a faint orange glow in all the tubes...heaters. If that glow isn't there they aren't going to work.
What model Marshall is it? The three small tubes are your preamp tubes and phase splitter. The two large tubes are the power tubes. If the large grey metal structure in the power tubes is glowing (plates) you definetly need to follow Maxes advice. With only three small tubes I doubt the reverb is tube driven. Could be wrong. Do you have any spare tubes to try?
Does the amp have any kind of footswitch jacks or effects loops? Get back with a model number or better yet, follow Maxes advice and take it to a tech, a completely dead amp could be a crap load of things.
jason

5/20/2000 3:54 AM
Black Friar	Hi, Yeah found out that one of the preamp tubes was not glowing any more. Buying some more Marshall ones, hopefully this place the shop is ordering from has some otherwise will be a bit of a wait. If everything seems ok do you think a rebias and a check from the tech guy is still needed?

5/20/2000 5:49 PM
Max	Hi Black Friar. Reread Jason post,and make your mind about the plates,he was righter than me,cos he explained more.When you stated orange glow and burned tubes,i just asumed that you knew the difference between glowing plate and filament glow. Best regards. http://photos.yahoo.com/satamax>Max.

5/20/2000 6:12 PM
jason	If it was my amp I'd just stick the new tube in and go jam! jason

5/21/2000 1:35 AM
Black Friar	Yeah thats I was thinking too. Thanks for all the help guys, both of ya's. You helped out a troubled Aussie suffering tube amp withdrawles. Only thing is we have to wait for teh Marshall tubes as nobody seems to have any. Don't really want to get the other brands so we don't have to rebias anything. I'll check that plate or filament glow out but I think we've found the problem. Thanks guys

Page 1 of 2