5e3 power transformer?

[chuckb]

hey guys, i have a 5e3 amp here on the bench and the guy that owns it says in just stopped working after a gig.
He thinks it may be the power transformer. i opened up the amp and there are no visible signs of any bad,burnt,blown components. the amp keeps blowing fuses when turned on. i have the power tranny taken out of the amp and it's a weber wo25130 power tranny. i did a ohm check on the following leads and here's what i got.

Primary- 3.4 ohms
secondary- two red ht together=16.7ohms, one red with ct =33.4ohms, other red with ct =48.7ohms.
- two 6.3 heater windings together =.4 ohms. with ct .4ohms each.
- two yellow =.5 ohms.

the tranny has two red ht @680v/150ma and two whit/red ht @540v. If it is the the 680v ht that is the problem, can i use the 540v winding instead?

[The Dude]

Transformers are usually the last thing I suspect. They rarely fail. Since you already have it out of the amp, I would apply power to the primary via a light bulb limiter or current limiter, if you have one, and measure the secondary to see exactly what it's doing. You could also bring it up slowly on a variac while monitoring current. If it still draws massive current with no load, then it's bad.

[dstrat]

^^^ The Dude is right!

It looks to me from the readings you posted the PT is fine, put it back and pull rectifier tube and output tubes, still blowing fuses?

[mac dillard]

https://www.premierguitar.com/articl...ormer-tester-1

give it a try.

[g1]

As to your second question, if the 680V winding is shorted, you won't be able to use the 540V tap either.

[chuckb]

hey guys, thanks for all the replies. I hooked it up to my current limiter like dude suggested and the bulb lit up like a christmas tree. I guess that says everything, internal short.

[The Dude]

Well, that's a bummer. It should draw almost no current unloaded.

[chuckb]

ya, it's a bummer for sure. Thanks again for all your help.


chuck.