I think you're describing a bridge rectifier. I had a similar problem with Rogue M120 monoblocks - the bridge rectifiers were undersized for the current that was going through them, and were cooking one of the wires. Under guidance from Mark from Rogue, and with larger replacement rectifiers he sent me, I was able to swap them out. Some minor replacement wiring was necessary to replace the damaged wires. If you take on a repair yourself, make sure you understand the safety issues of working on tube equipment - (how to discharge capacitors safely etc) as there is potentially lethal voltage inside tube equipment even when powered off. This would be a simple job for any competent tech.
rogue dronus magnum issues
I have purchased a rogue audio magnm that has played beautifully up till now, it's now dead. wont' even power up! I am going to contact Rogue. but I bought it second hand so I have no warranty. There is a potted squard section in the middle of the amp where 4 wires come in and are terminated. One of the 4 wires is burned insulation with exposed wires. I suspect this is the problem. How it happened I have no idea, I am running Martin Logan Aeris i's which are a difficult load but I would have assumed this would knock out the output tubes if abything? Help!!