Ampeg BA-115 Help Please!

[GrahamLeduc]

Howdy guys!
I've got a friend who decided that since his amp was blowing fuses that he'd bridge the fuse section and run it. Low and behold, he fried R31 and R49.

I've since replaced both resistors and got a fuse of the correct value and fired it up and it did just that; fired up. Both resistors blew again, but the fuse did not.

I'm basically an R&R guy with a soldering iron and multi-meter. Any and all help would be appreciated.

Thanks!!!
Graham

[dwmorrin]

The resistors blew because something is causing lots of current to flow there and it blew again since the problem is still in there.
Q5 seems like the obvious one to check first. Look for low resistance readings between the terminals.

This is a good time to get yourself a light bulb limiter if you don't have one.

[GrahamLeduc]

Yup, looking at .6ohm on Q5 and 1.2ohm on Q2. I guess I should start replacing those and see what happens next?

[dwmorrin]

Pull those, check EVERYTHING in there back to R22. Doesn't really take that long. Just make sure diodes, transistors check out and that you catch ALL damaged resistors.

And I would look into the light bulb limiter. You won't go back to square 1 if you miss something.

[GrahamLeduc]

Will do.
The build looks easy enough for a light bulb limiter; I'd be stupid to try everything again without one!
Thanks for your help dwmorrin!

[The Dude]

And, by all means, please remember to put the tinfoil back around the fuse after you have it repaired.

[GrahamLeduc]

And, by all means, please remember to put the tinfoil back around the fuse after you have it repaired.

haha! He was a little more resourceful than that; used a piece of non-insulated wire. The inside of this amp definitely looks like a horror show though. Damn!