McMICHAEL M21T

The picture will not stay still for long but when
it does it is slightly negative and all objects have a bright line surrounding them. The contrast does
not seem to work either. -G. Gorodini (Ewell).
This seems like overloading of the video
amplifier: also indicated by lack of operation
of the contrast control; the set now probably running in its full -gain condition. Check the
contrast control, the associated supply circuits,
and the vision i.f. and tuner valves that are controlled (i.e., from the vision a.g.c. line) as a heater /cathode short in one of these could cause the effect.