[TMC] That pesky PAL 350/500

[Chris Bolkan]

Hi TMC lovers!

As you know I'm struggling with my PAL 350. Power output isn't near what it
should be. The help and comments from the group so far have been wonderful.
A lot to think about and digest, but so far no ah-ha moment.

Right now the amp is apart in order to focus on what looks like it could be
the problem or at least a contributor.  Screen grid voltage is fed through
inductors to pin 1 on the final sockets (screen grid) and inside the final
sockets is supposed to be a 1000pf capacitor from pin 1 to ground.

I'm struggling with this 1000pf capacitor built into the tube socket.  I'm
not seeing any evidence of it visually or by measuring it. Both sockets
read exactly 4pf from pin 1 to the case of the socket which is the part of
the socket that mounts it to the chassis.

A lot of the socket is translucent plastic and the pins all look exactly
alike in the plastic. Where is the capacitor hiding? I know these are the
original sockets. All the screws have the TMC marking dope on them. There
are no external 1000pf caps on the pins but 1000pf caps are shown on the
schematic. This amp must have worked as shipped from the factory.

Has anyone ever taken one of these sockets apart to see how they
implemented the capacitor?

I'm so stumped. How did they both fail EXACTLY the same way? Im my world
that doesn't happen very often.

Thanks as always!

Chris
KI7NXY