5150 III burning smell ( troubleshooting help needed)

[SFW]

So during practice last night I started to notice that sour burning electronics smell. (Oh yea...). After poking around several pieces of gear, I realize that the smell is coming from my 5150 III head. The smell was strongest around the power transformer side of the amp where the AC power cable plugs in. I turned the volumes on the amp down a bit and the smell lessened, but never really went away. Any of you amp gurus want to take a stab at what might be going on?

 

[Kapo_Polenton]

You blazed way too fast across the fretboard and were essentially in the process of melting your amp!!

I am not a guru by any means but in my experience, obviously check your power tubes first. Is there any loss of volume?

Second, take the chassis out and look at the big resistor across the power tubes. Is it burned? Happened to my JCM800, loss of volume but also a horrible burning plastic smell when it went.

While you are in the chassis, look elsewhere for burned or bubbling components. (resistors/caps).

That would be the basic stuff. Make sure that all passes a clean bill of health before suspecting other stuff like a transformer. I would lay it chassis side up so all the components are facing you and play the amp, see if you can pinpoint where that smell is coming from. Does it smell that way this morning after sitting all night? Start fresh and take it through it's paces and see at which point the smell comes back.

 

[DAMIAN The MAN]

I guess you need a new one. A STEALTH !

 

[slaveunit]

If you don't see anything, don't forget they all have a 5 year transferable warranty.

 

[petee]

You have two choices:
1. Bring it in, pay a fee, and they may or may not find something.
2. Play it until it breaks or the problem disappears. In all honesty, if the amp still produces tones, it's probably fine. Could been a dust bunnny that was vaporized, who knows.
Was this first time you've run it hard?

 

[Mailman1971]

ouch....didn't you just do the mod to the amp?
I have no clue about modding but could that of done it? Sorry if noob question.
No clue about amp boards etc.

 

[SFW]

Yes, I did just mod the blue channel. Not sure if that would cause the issue that I'm having. This is the first time I've run the amp with channels 2 & 3 with the master volumes at 11:00 for an extended time. I nomally have the about 10:00.

 

[Kapo_Polenton]

Check all the solder joints you made when you did the few changes to the mod. Check for any burning of components around the area you modded. Besides that who knows, giv'er till she goes boom!