no sound from amp but FX Loop works

[bryan_kilco]

I know there are threads about this somewhere but I couldn't find anything in search.

My buddy has a DSL that powers on but no sound comes out of the speakers and the fx loop apparently still works. He's states away from me so I can't physically check the thing out. Figured I'd ask around here.

The loop runs off the preamp section, correct? So it may be something like tranny or power section? Or am I completely wrong?

 

[bryan_kilco]

Almost 100 views and not a single post?

 

[hsinn3r]

I know there are threads about this somewhere but I couldn't find anything in search.

My buddy has a DSL that powers on but no sound comes out of the speakers and the fx loop apparently still works. He's states away from me so I can't physically check the thing out. Figured I'd ask around here.

The loop runs off the preamp section, correct? So it may be something like tranny or power section? Or am I completely wrong?

That sounds about right, check power amp/speaker

 

[AntonioPetrole]

I posted a thread like this a while ago, I took out all the tubes and put contact cleaner on them and reseated them, works fine now. When I would flip my standby switch, the light didn't light up and there was no sound.

Edit: Here is is
http://www.ultimatemetal.com/forum/backline/869715-did-my-5150-just-die.html

I also changed the fuse. I think you were in the thread too haha

"I know this is already resolved, but I would like to chime in for anyone for future reference. If the amp makes no sound and the standby light doesn't turn on, it means that there is no HT+ or high voltage supply to the tubes from leaking caps which will subsequently blow the HT fuse or one of the two fuses (if not both) that are responsible for the +/-24v and -50v bias tap have blown, usually from bad tubes. The only other possibility is that the standby switch is broken. If you get no sound from the FX loop send, it means that the HT fuse blew and if you do get sound, the fuse from the +/-25v rail blew.

In the case of the OP it was the low voltage rail's fuse which is responsible for signal clamping in the preamp, and the biasing of the powertubes, which will cause the amp to be rendered useless.

As a rule of thumb, if the standby light doesn't turn on, it isn't just faulty tubes, something else in the amp, usually the fuses went out."