On Mon, 22 Nov 2004 11:07:02 -0500, "Rutro"
wrote:

I have a 41 inch RCA tv with a focus problem. When adjusting the focus pot
on the Flyback I see little to no effect. Only thing you can see happening
is a slight change in brightness. I also tried using the sharpness
adjustment on the video setup menu as well with little change. Any
suggestions? Should I change the flyback.


Either the flyback is bad, or the CRT has a short. Focus to G2
(screen) shorts aren't unusual. Try measuring the G2 pin on the CRT
while varying the focus. If you see any change the in G2 voltage, try
again with the CRT socket unplugged. If the interaction goes away
with the CRT unplugged, the CRT is bad. If you have a meter capable
of measuring to 10kV, you can try the same test on the focus voltage.
If the CRT is shorted, it may be possible to save it. I've cleared a
few by disconnecting the G2 wire and grounding the G2 pin while
turning the focus to maximum. Sometimes this is enough to blow out
the short. If that doesn't work, I've saved a few by grounding all
the pins of the CRT except focus and applying an external HV source to
the focus pin (with the CRT socket unplugged). Possible exposure to
high voltages are obviously involved, so don't try this unless you
know what you're doing.
Andy Cuffe