Lines running diagonally on a 19" dell (Sony) P991 monitor *Fixed*

[DaOld Man]

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Edit: This monitor is a 19" not a 21".
Link to the thread where this problem is discussed in greater detail:
Click here
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I posted this in "Project Announcements: Rotate monitor construction",  but thought I would re-post it here, maybe some of you monitor experts can tell me what is going on here..

I hooked everything up to the 21" Dell trinitron I was planning to use. (On the back it has "Ultrascan P991").
With the screen turned vertical, mspacman is huge!
Anyway, the screen degausses each time the monitor is turned on, so the degaussing shouldnt be an issue, since I plan to turn off the monitor while rotating it.
I do see a problem with the monitor. It has very thin lines, white in color, first line running diagonally from upper right corner to the left, dropping about 1/2 inch. The next line is about 1 inch below the first, following the same pattern. More lines follow each spaced about an inch apart, filling the height of the screen.
These lines are not real noticeable, but I dont like it.
On Zaxxon, the ship kinda shifts shape when it passes through one of the lines.

Anyone know what could be causing these lines?

[Kevin Mullins]

If it were an arcade monitor I'd say turn the SCREEN voltage down a tad on the flyback.
This can be done on a pc monitor just the same, but you'd have to open the case to reach the flyback.

The degauss functioning the way you think may not work even if you turn it off when rotating. Generally the monitor degauss components need to "cool" before it will degauss again. But you might get lucky and the time it takes to rotate may be long enough.

[DaOld Man]

Thanks Kevin..
Is the SCREEN voltage a pot? If so, is it marked so I could easily see it?
I have zero dollars invested in this monitor, (it was given to me by a friend), so I dont want to put a lot of work into it, but still it looks like a very nice monitor, other than the lines.

[DaOld Man]

I found a pot marked "VOL1" (Or "VOLI").
It is on a board mounted to the side of the tube's neck.
I tried adjusting this pot, the lines only scrunched up closer together. So it is probably not the pot you mentioned.
BTW, I googled for this monitor, hoping to get some pictorial info and found it is a 19" not a 21".
I measured it to be sure, and it is 19" (Measures right at 18" diagonal).
A friend gave it to me, he said it was 21". I just took his word for it. (Gift Horse).

[Kevin Mullins]

Yeah, it's a pot. But not like you're thinking on the chassis. This one is on the flyback itself.
The llarge black thing with the anode lead coming out of it going to the "suction" cup on the tube. (careful around the anode lead and cup)

You should find two pots on the flyback..... one is SCREEN and the other is FOCUS.
Alot of flybacks will have them labeled.

[DaOld Man]

Thanks again. I found the pots, I cant see any label on them, but the flyback is behind a metal shield so the labels may just be blocked. The shield has holes to reach the pots with a tweaker screwdriver.
I adjusted both, neither helped the lines, and both seems to affect the focus. Just a small adjustment throws focus way off.
But the lines are still there.

[DaOld Man]

Here is a picture of the lines..

[SirPeale]

Turn down your contrast.

[DaOld Man]

Thanks, but Ive already tried contrast and bright, and colors.

[SirPeale]

Then definitely the screen control.

[DaOld Man]

Thanks for the help Kevin and Peale..
You know, it might be a contrast problem.
If I turn contrast all the way down it doesnt change much, but it doesnt take much turning it up to wash everything out.

[DaOld Man]

I think I have this problem fixed.
I downloaded a program called windas that allowed me to hook a rs232 to ttl adapter between the monitor and the PC.
(thanks to richms for the info about windas!!)
I had to change the G2 setting on the monitor from 98 to 83.
Background is black on bootup and the lines are gone.
I still need to tweak the colors a little, but it looks fantastic compared to what it did.
Thanks to all who gave me advice.
Question: I tried adjusting the pots on the flyback transformer. I broke the paint that had the pots secured.
I think I got the pots back to where they were to start with, but what do I need to put back on them to secure them again?
Will some household stuff work? Im thinking nail polish?

[grantspain]

you don't need to do anything,if the pic is good then don't worry-the pots will not move on their own

[Kevin Mullins]

Agreed .... you shouldn't have to worry about those pots on the flyback.
Set then and forget about them.   

[DaOld Man]

Ok, thanks guys!!