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JVC AV 27850 - common cause for deflection problem?

Hi: The vertical deflection went out on my TV a few days ago. It started acting funny a few days prior to it going out altogether. I'd turn the set on and the thin horizontal line would appear, then fully deflect, and oscillate back a forth a few times, sometimes staying a line for a min or two, then deflect to full screen, etc. Now it just stays on as a thin horizontal like across the screen, about 1/8" thick.

Are there any things prone to failure in this set that I should look at? OR, any common problems with this set in general? e.g. bad solder joints around? Thanks for any insight! John

Reply to
John Hudak
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Solder connections - if the ouput IC hasn't blown by now. Sometimes if you put it off, the things blow up.

Mark Z.

Reply to
Mark D. Zacharias

Hi Mark: Thanks for the reply...when you refer to 'ouput IC' I assume you mean IC421 (LA7832 -that produces the deflection)?? Very interesting second part of the story...sometimes I can get back to normal deflection by cycling through the input selections (AV1, AV2, and TV)...the changing of the input signal sometimes triggers the deflection to operate normally. After maybe 3-10 mins, something happens and the deflection goes away. Guess I need to poke around with a hot soldering iron...Any additional comments based on this follow-up info? Thanks

-J

Reply to
John Hudak

The fault symptom looks like there are dry joints around the vertical output stage. Take the back of the set and lightly tap the circuit board with the handle of a screwdriver and confirm that it reacts when tapping the board.

Will.

Reply to
Will Hoevenaars

On this set, usually just soldering the pins of the vertical output ic will fix it. Chuck

Reply to
Chuck

After taking it apart, I resoldered all the connections in the vertical deflection section and checked the voltage out of the regulator. Since I didn't want to reassemble it without possibly fixing it, and since the set had some other flakey operation, I decided to resolder mostly ALL the connections - mainly the horz deflection, the CPU, the tuner board as well as the two massive connectors from tuner to MB, and the convergance board (on the back of the CRT). The old shotgun approach...

One hour and 15 min later + 1/4 lb solder, I reassembled it and it has been working fine...even the annoying intermittent turn-off/turn on problem seems to have gone away. I declared success and put it back on the TV stand...

Thanks for all the advice! John

Reply to
John Hudak

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