Dell Ultrascan P780 ghosts and fades?

[GTO69RA4]

I ran across a Dell Ultrascan P780 a few days ago. Flat CRT, made 1999. When
you first turn it on, lines on the screen (like window borders) ghost very
slightly. After about 3 minutes it fades to black over a few seconds. Don't
know about the ghosting, but thr fading out sounded like a loose joint going to
the tube heater. I prodded around for a while with an insulated probe but
couldn't jar anything into working again.

What's the likely problem? Are the two defects related? Could the heating
element be bad or is there something other than a bad solder joint that could
cause it?

Thanks

GTO(John)

 

[John Gill]

GTO(John):
I just repaired one of these P780 a few days ago. It had real strong
ghosting next to all the characters on the screen. I had an old junked
chassis that had high-voltage problems. I took the CRT neck board from
the junked one and put it one the one with the ghosting problem.
Perfect picture.

Most of the time, the ghosting problems are caused by bad capacitors on
the neck board. Either the internal resistance (ESR) of the capacitors
goes up in value reducing the action of the capacitor, or the capactance
itself goes down. If you have no way of checking the capacitors, I would
just replace all of them. There are not that many on this board.
Especially replace the one near the video amp IC (the IC with the little
heat sink on top of it).
Hope this helps...
John