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From: Jim Yanik on 28 Feb 2010 09:10
Michael Shell <news1(a)michaelshell.org> wrote in
news:20100228004851.0c71229b(a)bashir:

> On Sat, 27 Feb 2010 20:25:26 -0800
> David Nebenzahl <nobody(a)but.us.chickens> wrote:
>
>> Well, I tried cleaning the dust out of my Dell-branded Trinitron tube.
>> In so doing I seem to have knocked the convergence out of whack, even
>> though I was really careful vacuuming around the CRT.
>>
>> There's an on-screen convergence control, but even with it cranked all
>> the way over (to 100/100 for the horizontal control, 76 for the
>> vertical), there are still highly visible "ghosts" on screen.
>
>
> Try demagnetizing it first, especially if your monitor has a built-in
> degaussing button. The next step is to degauss with an external
> demagnitizer. There are TV degaussing coils for this (check Ebay), but
> you might be able to make do with something like a bulk tape eraser
> if you already have one.
>
> Color convergence problems will show up as red, blue or green outlines
> and/or duplicate images - like when the colors don't align on newspaper
> comic sections. If the ghosts you see are not in different colors,
> then it is not a convergence problem. The focus control is often very
> easy to unintentionally turn although a misadjusted focus control
> generally causes blurriness rather than ghosts.
>
>
> Cheers,
>
> Mike Shell
>
>
>

first,there's a difference between "convergence" and "purity".

when setting up a CRT,you first adjust purity,by displaying a red screen
and adjusting yoke magnets for even color and no green or blue areas.
But before that,you degauss with an EXTERNAL coil,as the internal coils are
not powerful enough.

Convergence is adjusted by displaying a crosshatch or dot grid and
adjusting the appropriate controls to merge the R-G-B lines or dots to make
white lines or dots.
On some sets,you may also have to use adhesive magnet strips to achieve
decent convergence in the corners.I used to do this at Tektronix on their
650 and 670 series monitors.

--
Jim Yanik
jyanik
at
localnet
dot com
From: Baron on 28 Feb 2010 12:00
Mark Zacharias Inscribed thus:

> "David Nebenzahl" <nobody(a)but.us.chickens> wrote in message
> news:4b8a0cd8$0$2363$822641b3(a)news.adtechcomputers.com...
>> On 2/27/2010 9:48 PM Michael Shell spake thus:
>>
>>> On Sat, 27 Feb 2010 20:25:26 -0800
>>> David Nebenzahl <nobody(a)but.us.chickens> wrote:
>>>
>>>> Well, I tried cleaning the dust out of my Dell-branded Trinitron
>>>> tube. In so doing I seem to have knocked the convergence out of
>>>> whack, even though I was really careful vacuuming around the CRT.
>>>>
>>>> There's an on-screen convergence control, but even with it cranked
>>>> all the way over (to 100/100 for the horizontal control, 76 for the
>>>> vertical), there are still highly visible "ghosts" on screen.
>>>
>>> Try demagnetizing it first, especially if your monitor has a
>>> built-in degaussing button. The next step is to degauss with an
>>> external demagnitizer. There are TV degaussing coils for this (check
>>> Ebay), but you might be able to make do with something like a bulk
>>> tape eraser if you already have one.
>>
>> No bulk eraser, but I do have a couple of tape head demagnetizers;
>> wonder if they'd do any good. But the monitor has a built-in
>> degausser anyhow.
>>
>>> Color convergence problems will show up as red, blue or green
>>> outlines and/or duplicate images - like when the colors don't align
>>> on newspaper comic sections. If the ghosts you see are not in
>>> different colors, then it is not a convergence problem. The focus
>>> control is often very easy to unintentionally turn although a
>>> misadjusted focus control generally causes blurriness rather than
>>> ghosts.
>>
>> It's definitely a convergence problem. I can see the colors shifting
>> when I adjust the on-screen convergence control, but not far enough
>> to eliminate the ghosts (which are definitely in different colors).
>> The focus is fine.
>>
>>
>> --
>> You were wrong, and I'm man enough to admit it.
>>
>> - a Usenet "apology"
>
>
> If it does relate to degaussing, the built-in coil, while not strong
> enough to fix it on one or two tries, might get the job done over the
> course of time, which is to say, a certain number of degauss cycles.
> Sony CRT's can be damaged by conventional hand held coils, though in
> practice I've not seen this happen. I think that particular caution
> only applied to their larger CRT's.
>
> Mark Z.

Simply rotating the screen 15 - 20 degrees is enough to cause colour
patches to come and go in the corners on my Trinitron tubed iiyama.
The Trinitron tubes seem to be very sensitive to any magnetic
disturbance.

--
Best Regards:
Baron.
From: Robert Macy on 28 Feb 2010 13:34
On Feb 27, 10:32 pm, David Nebenzahl <nob...(a)but.us.chickens> wrote:
> On 2/27/2010 9:48 PM Michael Shell spake thus:
>
>
>
>
>
> > On Sat, 27 Feb 2010 20:25:26 -0800
> > David Nebenzahl <nob...(a)but.us.chickens> wrote:
>
> >> Well, I tried cleaning the dust out of my Dell-branded Trinitron tube.
> >> In so doing I seem to have knocked the convergence out of whack, even
> >> though I was really careful vacuuming around the CRT.
>
> >> There's an on-screen convergence control, but even with it cranked all
> >> the way over (to 100/100 for the horizontal control, 76 for the
> >> vertical), there are still highly visible "ghosts" on screen.
>
> > Try demagnetizing it first, especially if your monitor has a built-in
> > degaussing button. The next step is to degauss with an external
> > demagnitizer. There are TV degaussing coils for this (check Ebay), but
> > you might be able to make do with something like a bulk tape eraser
> > if you already have one.
>
> No bulk eraser, but I do have a couple of tape head demagnetizers;
> wonder if they'd do any good. But the monitor has a built-in degausser
> anyhow.
>
> > Color convergence problems will show up as red, blue or green outlines
> > and/or duplicate images - like when the colors don't align on newspaper
> > comic sections. If the ghosts you see are not in different colors,
> > then it is not a convergence problem. The focus control is often very
> > easy to unintentionally turn although a misadjusted focus control
> > generally causes blurriness rather than ghosts.
>
> It's definitely a convergence problem. I can see the colors shifting
> when I adjust the on-screen convergence control, but not far enough to
> eliminate the ghosts (which are definitely in different colors). The
> focus is fine.
>
> --
> You were wrong, and I'm man enough to admit it.
>
> - a Usenet "apology"

In a pinch, you can use a cheap AC powered pencil sharpener. I once
had to do this and the convergence was actually better than it had
ever been before.

Except, be careful, or you can permanently warp the nickel shield/
mask. Approach degaussing cautiously
From: whit3rd on 28 Feb 2010 14:36
On Feb 28, 8:41 am, Meat Plow wrote:
> On Sat, 27 Feb 2010 20:25:26 -0800, David Nebenzahl
> <nob...(a)but.us.chickens>wrote:

> >Well, I tried cleaning the dust out of my Dell-branded Trinitron tube.

> >There's an on-screen convergence control, but even with it cranked all
> >the way over (to 100/100 for the horizontal control, 76 for the
> >vertical), there are still highly visible "ghosts" on screen.
>
> >Are there any other convergence controls

> If it has static adjustments on the neck of the crt you may have
> disturbed those.

I second that.

So, center the 'onscreen' convergence controls, degauss, then power up
with the back of the monitor off, display a white-grid-on-black-
background
pattern, and adjust the ring magnets (usually nearer the electron gun,
in
the form of a pair of rings with tabs). Tabs apart gives higher
field,
rotating both rings together changes the direction. It's tedious,
but
rewarding.

There also may be small magnets glued around the yoke (closer to the
screen) that do fine corrections.
From: Chuck on 1 Mar 2010 10:10
On Sat, 27 Feb 2010 20:25:26 -0800, David Nebenzahl
<nobody(a)but.us.chickens> wrote:

>Well, I tried cleaning the dust out of my Dell-branded Trinitron tube.
>In so doing I seem to have knocked the convergence out of whack, even
>though I was really careful vacuuming around the CRT.
>
>There's an on-screen convergence control, but even with it cranked all
>the way over (to 100/100 for the horizontal control, 76 for the
>vertical), there are still highly visible "ghosts" on screen.
>
>Are there any other convergence controls I could adjust to get it
>closer, like pots on one of the boards? Or how about trying to tweak the
>deflection coils a tiny bit?
>
>This monitor is on its last legs, so I'm not going to be investing a lot
>(in terms of time, and $0 in money) in it. I'd just like to know if I
>can get a few more weeks or months of use out of it.
>
>Pity, really: when it worked well, this was an outstanding monitor.


See if it has an hstat control. If it does adjust it for good
convergence. Chuck
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