V4 Burning Smell - Help?

[skeevy]

I found an old Ampeg VT-22 locally and have been playing on it for a few months (bypassing the internal 12"s and going into an ampeg 410 bass cab). I decided to convert it to a head so it wouldn't be so big and heavy to transport. At some point, someone must have ripped out the ground from the power cable, so I also replaced the plug with a new 3 prong.

At some point in the process of removing the chassis, replacing the plug on the power cable, and putting the chassis back in its new cut down head enclosure, something must have gone wrong. I powered it up and the light turned on normally. While waiting for it to warm up before switching off standby, I ran upstairs for a glass of water. When I came down my guitarist told me he had just noticed a smell, which I also noticed. I immediately switched off the amp. The smell was pretty sinister.

Any idea what I could have done wrong, or where I should go from here?

Thanks in advance.

 

[waltdogg]

Probably should have replaced the whole cable for starters, to ensure there actually was a ground. When I got my VT-22 and before I converted it to a V-4. The amp had a NASTY buzz/hum. Although the power cable was a replaced, there was no ground wire running into the amp. Replaced it with a known good 3-spring that actual had a ground wire running the whole way through. Attached the ground to my chassis, no more buzz/hum.

There's also the possibility that the amp has just sat for a very long time and really just need a recap and it's power supply cleaned up.

 

[skeevy]

Thanks for the reply, waltdogg. I'm sure a recap and generally cleaning wouldn't hurt, but I'd been playing on it for a few months with no issues aside from having a "shocking" experience every time, and the size/weight of the thing, which were the two issues I was hoping to mitigate. The fact that the power cable plug clearly had a third prong at one point that was yanked out is what led me to believe that it was already wired correctly and grounded to the chassis, but I should have checked to be sure. I'll take a peak when I get home.

 

[megafiddle]

Pull the chassis back out and examine everything carefully. Those burning smells can permeate everything sometimes, but try to locate the source of the smell. I might be easier to locate after it airs out for a while.

Also look for a component that's noticably discolored from heat.

Assuming that it was caused by transplanting the chassis, try to find some visible wire or component that was disturbed during the process. Also check any fastening hardware that may have shorted something.

-

 

[nashvillebill]

It would not hurt to take the amp to a qualified tech.

"Shocking" experiences should not happen!!

 

[waltdogg]

Oh in that case. Something probably just "went" that was going to soon.