Admiral 14R12 Restoration

[Crist Rigott]

Originally Posted by old_coot88

Have you subbed the 6BQ6 yet? You van sub it with a 6DQ6 in a pinch. The 6W4 can be subbed with 6AX4 or 6AU4.

You failed to list voltage on pin 8 (cathode) of the 6BQ6. But on the schematic you indicate 5.6V. Are you still getting 5.6V there? If not, the tube is not conducting (or if it's too high, the tube is conducting too much).

Also try this - with the plate connector disconnected from the HV rectifier, use an insulated screwdriver and see if you can draw an 'air arc' from the connector. If the fly is putting out, you'll get an arc of a quarter inch or more. But don't short it to ground.

We'll start with this one first.
I added the voltage on pin 8. Listed voltage is 5.6v and I measured 6.3v.

Will do that arcing test next.

I have subbed the 6BQ6GT and the 1B3GT. Not much change in the HV. Actually what is installed is a 6DQ6GT. When I had good HV, I subbed a NIB 6QB6GT and the HV was lower, so I put the 6DQ6 back in.

I also subbed the 6W4 with no help.