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From: mm on 6 Apr 2010 15:30
Question 1: On a tv screen, what is the opposite of pin-cushioning
called?

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.
From: whit3rd on 6 Apr 2010 18:32
On Apr 6, 12:30 pm, mm <NOPSAMmm2...(a)bigfoot.com> wrote:
> Question 1: On a tv screen, what is the opposite of pin-cushioning
> called?

Barrel distortion. For the obvious reason...
There may be a 'pin amp' or 'pincushion' marked control that you can
tweak (but this would be a remove-the-case-back kind of job).

> 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.

That's usually where 'ghosting' shows up; there's a strong timing
signal
on analog TV just to the left of the picture, and if you have a
delayed ghost
of the timing signal, there will be a (usually dark) bar in that
position.
Ghosting has this symptom ONLY on analog transmissions, though.
Is your set on analog cable?

A second possibility is that the 'screen' adjustment is out of whack
(this usually lowers the contrast on the full display); if you have a
gray-bars test pattern (some DVDs come with such on 'em) it will fail
to have a good 'black' until the screen is readjusted. Screen
readjust
is very commonly required with age, and either an insulated
screwdriver
into the marked hole, or a remove-the-back-and-tweak adjustment is
likely to be available.

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

From: Arfa Daily on 6 Apr 2010 19:54

"mm" <NOPSAMmm2005(a)bigfoot.com> wrote in message
news:od1nr559jirj8gnlctsfnjn84u7bk7u72t(a)4ax.com...
> 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


From: mm on 8 Apr 2010 00:06
On Wed, 7 Apr 2010 00:54:07 +0100, "Arfa Daily"
<arfa.daily(a)ntlworld.com> wrote:

>
>"mm" <NOPSAMmm2005(a)bigfoot.com> wrote in message
>news:od1nr559jirj8gnlctsfnjn84u7bk7u72t(a)4ax.com...
>> Question 1: On a tv screen, what is the opposite of pin-cushioning
>> called?
>>
>
>In the UK, we always called it "barrel distortion"

And here to it seems. Now I can tell all my friends I have barrel
distortion. They may not care, but I will enjoy saying it. At least
to one or two people.
>....
>> 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 ?

Even when there is oonly two vertical lines? Oh, yeah, that's exactly
what you say below.

>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,

That sounds right. Ringing, and right after it gets zapped back to
the left side.

This is close that it's probably enough to fix it. And I might be
able to find the H-linearity coil without buying an expensive set of
notes, so maybe if this gets worse, I'll save the tv instead of
throwing it away.

Do you want at the proper value for the damping resistor? If it's
been running hot, I probably can't tell.

>and produces a
>couple of vertical lines similar to what you describe, in about that sort of
>position.
>
>Arfa
>

From: William Sommerwerck on 8 Apr 2010 08:40
>> In the UK, we always called it "barrel distortion"

> And here, too, it seems.

Both terms are used in photography. Zoom lenses tend to have one form of
distortion at the long end, the other at the short end.


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