[R-390] Toasted R216 (2nd mixer plate resistor)

[Tim Shoppa]

In my yellow-striper's R-390A RF deck there's an obviously toasted,baked, and
swelled R216.  It's changed value to something in the hundreds of ohms
from its original 2200 ohms.

If this was part of a pentode mixer I would think that bad voltages on a control grid was
causing too much plate current.  But it's part of the V203 2nd mixer.  Could
really wacky AGC voltages (which sets the DC bias on the 2nd mixer) have caused
so much current flow that the plate resistor smoked?  I'd think that this would take
tens of volts

An alternative explanation might be a short in V203 (a 6C4), plate to filament, and
that doesn't sound likely.  Or (and this is the scariest) a short to ground inside Z216?

R215 on the cathode seems fine.  Normally whatever DC current goes through R216
would go through R215 too.

Any thoughts, experience?

Tim.