copper cap meltdown ... ???

April 18th, 2008, 11:40 AM
i recently posted about my brown '62 Pro crapping out during a gig, and several folks answered with possible solutions as to why the tubes weren't getting any high voltage.

took it in to my tech (Al Forbes of Charlotte), and he discovered that the copper cap rectifier had heated up to the point where the solder joints connecting the resistors and the glue that holds the cap on had melted!

the odd thing is, it was a one-set showcase gig -- the amp hadn't been on but about 40 minutes when it blew. Weber says the caps will last a lifetime if the amp is used "properly," and i've never heard of one melting like this. makes me wonder why the recto was running so hot ....

anyone ever heard of this happening before? Al patched it back up, checked over the amp and said everything was kosher, but it's got me spooked. may look into putting a tube recto in the amp.

April 18th, 2008, 12:17 PM
I've had mixed results with the Weber Copper Caps.

I had problems with the Copper Caps that throw off a lot of voltage (5Y3s, 5R4s, and EZ81s). The ones I used burned out pretty consistently. I was using them in Tweed Deluxe clones, 18Watt clones, and a couple of project amps. I use glass tubes for those applications now.

On the other hand, the 5V4 and GZ34 models, which throw off less voltage, seem to be pretty stable and I've had pretty good success with those. I'd definately recommend those models if folks wanted to try them out.

The only GZ34 copper cap that had a problem was in a heavily gigged AC30 clone. The copper shielding popped off. The owner went ahead and super glued it back and it's been running fine for over 5 years now. Given the amount of abuse that amp receives, that's actually a pretty good testiment to how hardy the GZ34 copper cap can be.

April 18th, 2008, 12:26 PM
mine's a 5U4 model, not sure where that stands in the voltage scheme, but it's somehow comforting to know i haven't been singled out for special persecution by the gear gods!

April 18th, 2008, 04:31 PM
This link will give you a relative idea of how much voltage these rectifiers drop:


The EZ81 versions don't drop that much voltage but the ones I used were in really small bottles which I think just got too hot in my amps. They may have changed since then.