vertical collapse on JVC AV 20TP4 television

[BlueMoon Mac Resources]

The above TV frequently has the picture collapse to the center one third of
the screen. Turning it off then back on sometimes cures it as does a sharp
rap to the side. It just started doing it a week ago but is getting
progressively more frequent.

I see a lot of chatter about the Thompson (RCA, GE, Proscan) tvs that have
the same problem caused by bad solder connections on the tuner shield
grounds. Is this tv prone to the same problem or are their other
possibilities?

I can solder, desolder, drain CRTs, work on static sensitive stuff (I repair
iMacs) so if it is simple I can probably repair it with some guidance.
Thanks to anyone who responds. adamAdam Tomash
BlueMoon Macintosh Resources
[email protected] (please remove yourpants)--

 

[Sofie]

Adam Tomash:
NO..... not a problem with "tuner grounds" in the JVC television. More
than likely dry, cracked or otherwise faulty solder connections near and
around the vertical output circuitry.
If you are not certain how to proceed with this repair you should go to the
website for this newsgroup at
http://www.repairfaq.org/
There, with some search time, you will find a wealth of specific
troubleshooting, repair, and personal safety tips.
Get this fixed right away..... if you wait and nurse this along, not only
will it NOT fix it self, but the problem will become worse and the repair
will be more extensive because expensive parts could fail.

 

[BlueMoon Mac Resources]

Thanks to Sophie and a direct reply from Jacques in Quebec I managed to fix
this problem with minimal effort. I removed the motherboard after making a
quick sketch of the wire placement for wires I had to remove and discharging
the CRT. I flipped it over and found the pins from IC 421. The solder looked
OK but I removed the old solder with wick and resoldered using a magnifying
light. Carefully inspect your work for bridging. Clean any rosin up and
reassemble. One wire on the video board (on the CRT neck) needs to be
desoldered to free the motherboard and then resoldered on reassembly. So far
it works great. I did not replace any components although I am sure it would
have been prudent. Thanks to all who make this newsgroup work.Adam Tomash
BlueMoon Macintosh Resources
[email protected] (please remove yourpants)--