Cary V12 - Output Tubes Problem

Try changing the fuse anyway. Sometimes there is a very small fracture that can't even be seen in the fuse. If that doesn't work, call Cary.

most-likely that is the fault of a power supply and less-likely you'll be able to perform that troubleshooting by yourself if you've never worked with high-voltage circuits (nearly 500V).

there are definitely fuses on the amplifier and i guess one main for power supply and the other is an output fuse. changing these fuses will unfortunately less-likely help.

were the previous tubes blown? did you try them on another side of the amp or placing them onto the working monoblock?

AISIP,

You should call Kirk at Cary Audio and explain which tube positions are not getting heater voltage. Chances are good that there is a fuse associated with that group of tubes.

In general tubes rarely all fail at the same time. So the catastrophic failure of three tubes is very unlikely. Normally there is one portion of the power supply that provides the heater voltage and one that provides B+ or High Voltage. I find it unlikely that there is a power supply failure if 9 of the 12 tubes are getting heater voltages.

With all that said you are most likely looking at a fuse or at very worst a burned resistor or resistors which in some designs like Audio Research act as fuses. Kirk should be able to help you further. Do be careful if you open the amp up. The DC caps in a tube amp can hold a charge for many days in some designs.