Ampeg B25B Blowing the fuse

[TerryD]

I'm used to working on Old Fenders which is, as you know, fairly simply.  This amp is a friend of mines.  I see one cap with an outside crack or slice.  I was going to change all the electrolytic caps but these are in the cans.  Any tips on doing those.  Also tips on overhauling this??


Also both transformers have a good deal of rust on the outside.


Please be simple.  Probably shouldn't be doing this, but I have done some extensive repair with your help a number of times but mostly on Fenders.



Thanks, Terry

[shooter]

Any tips on doing those.

are they the twist lock soldered type?  If so, mark all the wires, WELL, take a pair of dikes and cut the "tab" at the cap side, then just heat up the solder, suck n pry the little tabs out.

Also tips on overhauling this??

same as fenders, get the PS working without tubes, start adding tubes, fix each section as you go, keep an eye out for bad wires n solder joints and lead dress, and....
walla, fixed

[sluckey]

Find out why it's blowing the fuse before you start shotgunning parts. Use the same troubleshooting techniques you would use on any Fender.

[SILVERGUN]

This schematic shows 4 fuses:
http://el34world.com/charts/Schematics/files/ampeg/Ampeg%20B-25-B%20(8-72)%20Schematic.pdf

Which one is blowin?

[TerryD]

ALSO  I see this amp does not have the 5AR4 tube rectifier.  does that make it a different ?


I only see one fuse?


Other than this the front "looks" like an Ampeg B25B  There is no name that I can see.


Not only is there a lot of rust on the transformers, there seems to be rust or corrosion everywhere...like on the solder joints etc.

[PRR]

> I only see one fuse?

The plan Silvergun linked has four. Ampeg did sometimes draw one thing and build another.

The rust is extra mojo. It has NO effect on the transformer until spoonfuls of rust are missing.

Corruption on joints is less innocent. They may all need to be re-done before you get all the crap-outs out.

[shooter]

"looks" like an Ampeg B25B  There is no name that I can see.

I'd start there, don't even need meters, surfing, maybe

[davidwpack]

I rebuilt 2 of them recently. I had one can and a couple of individual caps The only problem I ran into was that all the grounds went to the can so I had to make a ground bus. The inside of the chassis is also painted so I sanded a couple tiny spots with the Dremel for the screws to make sure I had good contact. I think I used 50/50 uf for the can.