5150 volume issue!

[Onset to putrefaction]

Hey guys, i need opinions on this pretty quick, i've got a band coming in a few days. After a while of having the 5150 going through my mesa cab. the volume drops and it is really low, and i have to turn it WAY up to get it back to where it was...
Any opinions?
I am sure the Ohms are set right... i heard its the tubes.. but i think all the tubes are good.
I've also heard its the send and return loop?
a fuse problem?

ThAnks!
Alec

 

[53Crëw]

A tube going bad..... That's my first thought.

 

[Loren Littlejohn]

A tube going bad..... That's my first thought.

Same here.

Fallowed by possible OT craping out (and that would suck as they are not that cheap).

 

[yarrick19]

Hey guys, i need opinions on this pretty quick, i've got a band coming in a few days. After a while of having the 5150 going through my mesa cab. the volume drops and it is really low, and i have to turn it WAY up to get it back to where it was...
Any opinions?
I am sure the Ohms are set right... i heard its the tubes.. but i think all the tubes are good.
I've also heard its the send and return loop?
a fuse problem?

ThAnks!
Alec

I had this same issue and it actually turned out to be a bad preamp tube. I started by replacing all the power amp tubes and it didn't help. A new set of preamp tubes cured it for me.

 

[Keiffer]

exerciser the Effects Loop Jack.

 

[Melodeath]

This happened to me, although sometimes the volume would randomly jump back up to normal volume.

I didn't know what the issue was, but I figured it was tubes, so I took it to the repair shop. They replaced 2 preamp tubes and re-soldered some joints etc, for $100. When I got the amp back the volume issue was fixed but the tone was getting random scratch noises, you know that random noisy sound you get if you have a scratchy volume pot or a bad cable or something? They told me to switch the places of the 2 new tubes they put in, as sometimes tubes don't agree with the position they are in. Doing that that has pretty much done the trick. Any scratches I hear I now attribute to my volume pot on my guitar.

 

[Metaltastic]

exerciser the Effects Loop Jack.

...?

 

[Keiffer]

...?

Plug and Unplug several times. There is a contact that can become oxidized causing intermittent connection.

 

[KillDivision]

Plug and Unplug several times. There is a contact that can become oxidized causing intermittent connection.

Yep, common 5150 problem.

 

[SuperD]

Before anything else !! Some contact cleaner and plug a jack in and out several times, this is a common issue. Cheap fix. Try this before transformers and soldering.

 

[nwright]

I was going to recommend jacking off the FX loop jacks, too, but it looks like a few others have already recommended this action!

:zombie:

 

[VH100R]

exerciser the Effects Loop Jack.

that and maybe the PI preamp tube (last preamp tube)