RCA 41 inch TV with retrace lines? Repair tips?

[Rutro]

I have a RCA tv with the chasis number of CTC189BG5. Turn on when its cold
and picture looks great. About an hour later you here a snapping sound and
picture goes bright with retrace lines. Adjust focus and brightness on
flyback and nothing changes. Any suggestions on how to fix?

 

[Art]

Snapping sound from Kine or from HV circuit?? That should give you a clue
as to what may have to be addressed.

 

[Rutro]

Seems to be from the HV circuit. I was considering changing the flyback.
Any thoughts?

 

[Farmer Giles]

..com...

Seems to be from the HV circuit. I was considering changing the flyback.
Any thoughts?

Not familiar with the model but sounds like it could a be crt flashover.
Measure cathode and grid voltages of the crt when the fault is not present
and then see what changes when the fault occurs. Finding out whether it is
an increase in grid volts, or a decrease in cathode volts, should narrow
things down a bit - if it's not the crt.

 

[Pedro]

I've seen this fault, and it was an open circuit on the gun ie. no
return ie.
it was floating. Initial potential was ok, however a flashover raised
the potential and high beam current, took a long time to leak away.
I'd look for a crack on the neckboard, and a check for any feed
resistor gone open. (don't measure with component in-circuit)
Clean down the board with alcohol.
And look for the discharge in a darkened room.

Pedro

 

[Rutro]

Pedro,

Thanks for the advice. That sounds like a definate possability.I will
check that out tonight and keep you posted.