Help!! Bad Speakers Killed My Amp?

[ManRay]

Help,

My amp was working until I plugged it into a blown set of speakers. Not just flabby, fuzzy speakers but more specifically speakers that were making absolutely no noise. Now my amp is refusing to make any noise itself when plugged into a working cab.

Did these bad speakers burn up my Output Transformer?

I have swapped output tubes out for another set and eliminated that as the culprit.

What kind of damage could these speakers have done to my amp?

Thanks

[txstrat]

Have you checked the fuse(s)?
Some more details on your amp would be helpful. What amp? Combo? Top? Speaker jacks on the backside?
How long did you run the amp with the blown cab?
Have your heard any weird sound when you plugged the amp into the blown cab (that might have come from the output transformer)?
Did you smell anything burned?

[ManRay]

As per your suggestion I just looked under the hood to find that all 4 of the 250mA fuses that ran to the cathodes of each of the 6L6's in this crate tv-120 head unit were dead. I only ran the head to the cab for 1-2 minutes to test the speakers. No burning smell, and no noises at all.

Any ideas why this would have happened?

Could this maybe clue me in to the source of the problem I am experiencing with the blown speakers?

Thanks a million for the help! I will gladly replace 4 fuses over an OT any day...

[Steve Conner]

Well, replace the fuses and see if the amp works. If it blows up again when you turn it on, check for those little diodes that are sometimes installed between the power tube plates and ground: they may well have failed short.

If the sound is weak and your tubes overheat, then you've roasted your OT.

Your speaker cabinet probably had a loose wire or a burnt out voice coil. Running into an open circuit is the worst thing you can do to a tube amp: to use an automotive analogy, it's like leaving your car in neutral with a brick on the gas pedal.

[ManRay]

Fuses are in and the amp is alive once again! The sound is strong and the flyback diodes appear fine under visual inspection, but I have no way to test them beyond that. I think she'll live to gig another day. Thanks much guys!

Any suggestions for tackling a speaker repair job?

How can I test for a bad voice coil?

I really have nothing to lose at this point, and I would hate to let a learning opportunity like this be wasted.

Again, thanks a million for the help guys! My amp lives!