[Johnson] Viking II Problems

[Rich Soennichsen]

I have been trying to debug a Viking II, the saga so far:

re-capped

All low-voltage operations ok/normal.
When HV was initially applied there were fireworks and a blown fuse.
One wire under the HV rectifiers was melted and shorted to ground.
Several of the .01 and .001 ceramic caps shorted and burned.

I have tested and replaced tubes as necessary.

Initial setup on low voltage is normal.

Switching on the HV results in high plate current, 200-300 mA.
This current increases until the fuse blows.

Coupling is set to one and the final to zero.  I tried quickly tuning
the final but the plate current just shoots up anyway.

The drive is set to zero and I measure zero volts at the potentiometer wiper.

HV = 750V
LV= 350V
Negative Supply = -75V

I believe this high plate current has caused the overheated wires on
the HV side.  I am not sure what killed the ceramic caps, it is my
understanding the these are very robust, oscillations perhaps?

I am a novice and so I appreciate any direction from you all.

73

Rich