DX-100 audio problem

[Dale KG4KZG]

Hi fellow greenies, Have no audio on my DX-100 I pulled the mod. trans. to
check potting and it seemed ok. No shorts to ground and the resistances
seemed with in limits. Also, checked the driver trans, found no shorts. Last
night  plugged it back in and the 12BY7 driver and it got very blue and plate
started glowing a dull red then got brighter red to where  turned it off and
subbed it with a ok but marginal  tube and it did the same thing. Removing
the 5V4 LV rect. of course kept it from turning red again. The audio failed
during a 20m am qso about 6 months ago, no crispy critters no blown fuses.
I presume something in the screen circuit or cathode bias is the problem.
There are no voltages listed in the manual for the tube pin out.
Voltage on the plate is 375-380V and on pin 2, one of the screens its 175V.
Any ideas?
Can reply off list if you wish 73 and TIA
Dale
kg4kzg

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