On Sun, 26 Dec 2004 21:24:29 GMT "G"
wrote:

On
my 22+ year old RCA I've noticed for years a faint, approx 2-1/2" wide
horizontal "bar" in the background....just as if the picture was
at-a-different-depth while the bar slowly scrolls up the screen.

This is the classic "hum bar" pattern. It is 60 cycle noise
superimposed on the picture signal which is just a little under 60
cycles. (That's why it rolls slowly upwards.)

The source of this is either bad filter caps in the set's DC power
supplies, or 60 Hz interference from something else in the
neighborhood.

This Christmas I bought
a new Toshiba 14AF44 as a second TV for the wife and was surprised to find
the exact same abnomality showing up in it's picture.......no more or no
less than on my old RCA.

This makes it almost certain that the problem is radiated 60 Hz
interference, rather than a problem in the older set's DC power
supplies. I'm puzzled by your rather thorough troubleshooting,
however. If I understand correctly, you've already tried turning off
every other electrical item around and the problem persists.

I would extend this test, making sure that you have actually turned
off everything else. You may need to go so far as to turn off compact
fluorescent lamps and unplug items which have standby circuits. Unplug
all wall warts, turn off any lights that work on dimmers, disconnect
dimmers, turn off computer & UPS, etc.

Do you have neighbors hearby? Does this happen at ALL times? I find
that our microwave makes big hum bars in our house.

Once you've made the bars go away, you can turn things back on one at
a time until the bars come back. Then you've found the culprit.

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Jim Adney
Madison, WI 53711 USA
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