"mm" wrote in message
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Question 1: On a tv screen, what is the opposite of pin-cushioning
called?


In the UK, we always called it "barrel distortion"


Question 2: I have a 12 inch Sony color tv, with turret tuning and a
separate UHF turret tuner, with detents. I guess it's about 25 years
old.

I've been using it for about 2 months and, mayb surprisingly, the
opposite of pin-cushioning (OPC) doesn't bother me. I only notice it
rarely, when there are some vertical lines near the edges of the
screen, or at the end of a movie when the credits crawl by.

A couple days ago, within a day or less, two vertical lines appeared,
about 1.5 inches from the left edge, about a quarter inch from each
other, each about 2 or 3 mm. wide, the right one from the top of the
screen to the bottom, the left one from the top of the screen 9/10ths
of the way to the bottom, sometimes only to 2/3rds. The lines flare
out at the top and bottom, I presume because of OPC.

The tv hasn't been dropped or shaken or even lifted at all in the last
month.

This isn't a case of the picture folding over. The rest of the
picture is fine.

I thought it was dirt on the screen, somehow, but it's inside the
glass. It's visible when a tv show is on, when there is no signal to
the tv, and not visible when the tv is off.

I don't have much expectation of fixing this, but I would like to know
what it is, how it can happen.

What we used to call "striations" maybe ? Caused by velocity modulation of
the scanning beam, and was often due to the damping resistor across the H -
linearity coil either burning out, or running so hot that it crystalised its
solder joints. Without this resistor in place and working, the lin coil
'rings' a couple of times after the 'shock' of flyback, and produces a
couple of vertical lines similar to what you describe, in about that sort of
position.

Arfa