Hot Rod Deville 212

[diamond9er]

Hey, my R80 and R81 blew,
and I am planning on replacing them myself; however, does anyone know of any other symptoms/complications of this situation? Should I be looking at other faulty parts as well? What could have caused this?

[Robert M. Martinelli]

Hi and welcome to the forum!

R80 and R81 are there for hum reduction purposes, as they provide an "artificial" ( and balanced ) center tap to ground for the PT 6,3 VAC secondary winding ( heaters & pilot lamp ). If they have burnt open it's enough to replace both ( the amp works even taking those resistors out, though hum could be more audible ) as no other part should have suffered any damage IMHO. If they have shorted, the 6,3VAC secondary could have overheated, so you should check it for proper functioning.

As to the resistors' replacement, my advice would be to throw in a couple of 100 Ohm 1W resistors ( "half watters" are more likely to burn again ).

Hope this helps

Best regards

Bob

[Enzo]

Little or no current flows through the hum resistors normally, there is no path for current to flow. When they burn up, it is almost always because a power tube failed. A high voltage shorted to the heater. Alternatively, if one of your power tubes has a broken off index post on the base, the tube may have been inserted in the socket the wrong orientation. That could also easily have shorted high voltage to ground through those resistors.