I get a bright horizontal band plus what looks like a more-or-less properly proportioned, 2" high section of the picture directly below the band. It looks like I'm seeing a narrow window of the entire picture. Color and sound are fine as is the small section of the picture that is visable. The window I see is a tad short in width, but otherwise OK. I have already replaced the vertical IC (Sanyo LA78041) and the 2SD2499 transistor on the same heat sink, which had no effect on the problem. My next step is to check all the related vertical caps around the circuit. Any other suggestions?
Usually the 47 to a 100 mfd electrolytic capacitor although rarely the 1000 mfd 50 volt generally in and around the vertical output chip also just checking these capacitors may not reveal the defect so many times they may test good when they are bad the best way use substitution with jumper leads connect test shut off set go to next suspect turn set on .continue this you may find culpert.
There are two small capacitors that need to be changed in the vertical circuit.
You could do three of these change flyback change yoke change cap that couple the horizontal transistor.good luck
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Techman. Thanks for the advice on the two small caps. Could you please be a little more specific as to which ones? I've already checked about half the various ceramic and electrolytic caps in the vertical circuit and haven't found any bad ones yet. Unfortunatey, I don't have a schematic of the set, so I'm starting out at a disadvantage, but I feel there's only so many components in the vertical circuit.
One more related question. I have completely removed the main circuit board. Is there a way to power up the board without energizing the High Voltage? That way, I cound more easily use a scope to poke around the board. I'm a bit gun shy of trying that with the set on now. (Yes, I know about isolating the ground lead. I used to work with 3 phase 480VAC/600 Amp SCR circuits.)
I'm starting to feel really stupid about now. What exactly is the Y/c IC?
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