Express Dead

[Oswald1958]

OK.....I bought a Biastool. Instructions required a reading for cathode to plate voltage. I had the tubes in while taking this reading. Smoke started rising from the socket (filament wire maybe). Tube was not glowing anymore. The second power tube was glowing. Turned it off (obviously). Removed the tubes and re-checked. It showed 398V. Put the bias checker in with new output tubes. Turned it on and the fuse blew. Now.........You guys let me have it. I know I did something wrong, and hope it's not the trannie. Any help would be appreciated....Thanks guys. On another note....the bias tool has two different calculations for Class AB1 and Class A. What's the Express? Thanks again.

[Oswald1958]

O.K. Instructions said take reading from pin 8 (low) to pin 3 (high). That is what I did. Smoke. Should have taken pin 8 to ground?

Maybe this helps.

[Firestorm]

Which "biastool", specifically?

[Oswald1958]

SRS Biastool mA

[Firestorm]

Whe you took your plate voltage reading, are you sure you had your meter set to read volts (not mA)? If you accidentally were set to mA, you'd short plate to ground (which should have blown your fuse instantly). Could you maybe have accidentally tried to read pin 2 or pin 7? The tube stopped glowing which sounds like a heater problem. If the socket started smoking, you may have a carbon track on the socket. Examine the socket closely. How long was the socket smoking?