Weber 5E3 suddenly blowing fuses

[sparky]

My Weber 5E3 is suddenly blowing fuses as soon as I switch on the power.

This is before I flip the standby to send power through the entire amp.

About one second after I hit the power, the fuse blows. I've blown four fuses trying to find the problem.

The amp worked fine for six months and suddenly won't work today.

I can't keep power going long enough to try to find the problem...

I checked the mains and re-wired the switch and fuse, but no luck. I don't see any obvious shorts to ground (and wouldn't expect to find one after this long).

Does it sound like the PT?

[TD_Madden]

Pull all the tubes and try it again....

[hasserl]

PUll the rectifier tube / copper cap and see if it still blows the fuse. If not, replace the rectifier with new and try again.

I doubt it is the PT, but if the rectifier isn't the problem that is the next place to go to. But don't condemn it outright, yuou need to do a little troubleshooting first. Check continuity thru the windings, check for continuity across the windings, check for short to ground between the primary and secondary windings.

[sparky]

I've pulled all of the tubes and still get the same problem.

I wasn't using the copper cap; I was using a NOS GE 5Y3GT.

I'll see what I can find on the PT.

[stokes]

You say it is "suddenly blowing fuses" I assume the amp was functioning okay for some time?If it is blowing fuses before the standby is switched on as you say,the problem has to be either a short in the filament circuit or the PT.With all the tubes pulled check the filaments to ground with an ohmmeter if there is no center tap on the 6.3 fil you should get a reading above zero ohms on both sides of the filament,pin 2 and 7 of the power tubes.The 5volt fil should have no ground reference at all.

[sparky]

Yeah... The amp had worked for six months. Thanks for the advice.

I spent some time on the phone with Ted Weber this morning. We went through unhooking PT wires one at a time. We finally decided that the PT was blown, so he's sending a new one out to me.

[stokes]

Always best to go to the source.Ted is a great guy to deal with.Glad to hear you got to the bottom of this.