Westinghouse TV no picture : Strip or fix?

[electroking]

Hello again,

I don't think this has been suggested before. The cathode current of
the 12BY7A video amplifier is supposed to go through R-221, the contrast
control potentiometer. If there's anything wrong here, no video signal
will get to the CRT cathode.

With the set off, just pull the 12BY7A tube, connect one terminal of
your ohmmeter to ground and the other to pin 1 at the tube socket.
While rotating the contrast control, you should get a smooth variation
between 0 and about 500 ohms. If this is OK, fine, otherwise the
control should be cleaned, replaced, or temporarily replaced with a
resistor of about 250 ohms.

Once the previous check has been completed, you may reinstall the
video amplifier tube, power up the set and check the DC voltages on
the tube: +178 on plate (pin 7), -2 on control grid (pin 2) and +161
on sceen grid (pin 8). Note that schematic seems to be indicating the
-2 volts on suppressor grid (pins 3 & 9), but that does not make sense
as this grid is grounded. I do believe that the -2 applies to pin 2.
If anything is odd here, get back to us and we'll discuss.

If you have good sound, it means that the problem is somewhere
between the video detector (V-5B) and the CRT cathode, and
things are not that complex in this area. Bye for now.