PI screen with 50vdc

[surfsup]

I have an interesting issue on a liverpool build. A have 50vdc after my cc to the PI (50vdc on the PI screen that is fed from the cold biased stage). I already replaced that cap (sozo) with another one. Same 50vdc. I thought the cap was supposed to block that! Bad PI socket? I already rolled the tube.

Plates are both at 220vdc at idle
Cathodes are at 60vdc

When i strum the guitar, the plate on the side that is fine sags about 10vdc. The side with 50vdc on the screen hardly sags at all. Any ideas?

[martin manning]

I have an interesting issue on a liverpool build. A have 50vdc after my cc to the PI (50vdc on the PI screen that is fed from the cold biased stage). I already replaced that cap (sozo) with another one. Same 50vdc. I thought the cap was supposed to block that! Bad PI socket? I already rolled the tube.

Plates are both at 220vdc at idle
Cathodes are at 60vdc

When i strum the guitar, the plate on the side that is fine sags about 10vdc. The side with 50vdc on the screen hardly sags at all. Any ideas?

You probably don't have any issue at all. The grid (it's a control grid, not a screen grid) should be within a volt or two of the cathode voltage (60V) when biased correctly, which it probably is. You're measuring a bigger difference between grid and cathode because your meter is giving the grid a different ground reference when you try to measure it. The meter's input impedance is high, but not infinite, and you are upsetting the bias point. If you measure at the bottom of the bias resistor, you'll get something very close to the actual grid voltage.

[surfsup]

Damnit, i'm still a rookie...so simple. Thx!