6550 Tube Blew - A Few Questions

Connect dummy 50w/10Ohms resistor to each of the channel before testing.

Dunno what amp you have, so take what I say with a grain of salt. It's possible that the 6550 arced and blew a bias resister. OTOH, maybe it would just be better to call the factory tomorrow and talk to the folks who know YOUR amp.

Ok, having said that, I'll tell you my tale. I own an ARC tube amp, which uses (8) 6550 winged C tubes. [As an aside, I later upgraded to the KT-120s.] Doesn't happen often, but maybe twice since I've owned the amp I've blown power tubes. Both times the tubes took out a bias resister which means that I had to call in my friendly ARC authorized service tech to replace the resisters. It's an easy fix.

Well, the last time I blew a tube, I called the factory and asked if I could run the amp without the tube or with a fresh tube even though I couldn't bias it. The factory said if I did, I would invalidate the warranty -- so I didn't.

In your case, call the factory. But I'm curious what would happen if you dropped in a fresh tube. If it biases, then maybe you didn't blow a bias resister and the amp might be good to go.

Gary (Hifigeek), an authorized ARC service tech, once metioned on the Forum that even if the bais resister didn't blow, the tube arc might have changed the resister's value. Another reason to ask the factory.

Good luck and let us know how you make out.

Ok, thanks for the info. I didn't know about the bias resistor blowing. I'll certainly call Jolida today and ask about it, and where I can obtain 0service if necessary.

Iirc, the same thing happened once before, and I didn't need to replace a resistor. But, I was thinking, if its just a resistor, shouldn't be too difficult to do myself if I can be told which resistor. Another reason to call Jolida and do some Googling.

Terry