my friends 5150 is broken?

[brit84]

so we only get a low clean tone when plugged into the effects loop. no sound at all when plugged into the normal inputs. any suggestions as to what might be causeing this? its the 5150 combo version.

 

[Erlend_G]

Re: my friends 5150 is broken?

Maybe your guitar is broken?

Try a different axe.

 

[Marcel]

Re: my friends 5150 is broken?

maybe a preamp tube is dead?!

 

[brit84]

Re: my friends 5150 is broken?

guitars work fine, he told me that he changed the preamps with others with no effect

 

[Marcel]

Re: my friends 5150 is broken?

broken input jack would be another simple thing too check out.. (though don't look into the amp if you don't know what you're doing ** LETHAL VOLTAGES!! ** )
it seems to be something in the preamp (before the fx return)... the reason that the tone is low by plugging in the FX return is that this isn't build for pluggin in a guitar... that there is a sound let me guess the power amp is ok...

Maybe a job for a tech...

 

[Gearjoneser]

Re: my friends 5150 is broken?

First, change all the preamp tubes.....swap them out of another amp, before buying new ones, just to diagnose the problem.

Make sure the input jack isn't broken.

Sometimes, the jacks for the FX loop need a good cleaning with contact cleaner, so they aren't shorting out the signal. If the preamp or FX loop circuit is open, due to a bad jack or tube, the only way you'll get sound out of the amp is by plugging into the FX return.