B-52 ATX 100 biasing

[goldtop5]

Does anyone know how to set the bias on a B-52 ATX 100 tube head?

[The Dude]

Hard to say without a schematic. Does it have cathode resistors? Do you have a bias probe?

[g1]

There is a fuse that goes to the primary of the OT. You can pull the fuse and do a current measurement there, which will tell you the current for all 4 power tubes. Divide by 4 and multiply by the plate voltage number. This will tell you the idle dissipation of each power tube in watts.

[Jazz P Bass]

To add: if the heaters are in parallel, you can use the G1 method to measure each tube individually.