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Ultrascan monitor Dell P991

Hi, This is a Sony Trinitron monitor which I like very much. Its performance is awesome, unfortunately it has begun giving me picture troubles. Maybe a year ago, I had to continously decrease screen brightness and contrast to compensate for the monitor's own increase of these parameters. Today I'm using brightness of zero and contrast of say about 20. This will give me a decent picture. If brightness and contrast are turned up, retrace lines are seen. Also, the screen when it should be all black, is more like purple. This gave me an idea of a too high G2 voltage. But I was amazed when trying to decrease G2 (on the HVT), this actually changed the focus! Of course, the focus pot changed the focus aswell. It seems like there is some short between G2 / focus circuits??? Any advice is appreciated. I'm an electronics engineer of switching power supplies so you don't need to give any advice like "bring it to a technician", I'm well into electronics.

Regards PAF

Reply to
powerampfreak
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Both the focus and G2 bias are from the multiplier unit. The monitor is designed to compensate the focus as best possible for the aging of the CRT. As the CRT ages, its current characteristics change.

There is compensation for the individual electron gun emissions, and also for the focus voltage to maintain the best possible performance through the life of the CRT. There will come a time, when this can no longer be compensated for, because the CRT emission will decrease past practical limits. At the same time, there is the deteriation of many of the capacitors in the unit.

From your description, you are dealing with a monitor that has aged components and a CRT that is starting to go weak.

Check out the new LCD screens. They are incredible, and better for your health. They have almost zero EMR, no UV radiation, and no X-Ray radiation. Also, there are no miss-convergence or purity errors.

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JANA _____

Regards PAF

Reply to
JANA

Hi Jana,

But what about G2 adjustment? Why cannot this be adjusted at all? I realise the automatic focus adjustment, the focus are still perfect. What concerns me is that I'm unable to change G2.

Regards

Reply to
powerampfreak

Go into the color menu and run the "color return" feature. This should completely fix the problem. Note that it won't let you do this until it's been on for about a half hour.

That monitor doesn't have a G2 pot. Both of those controls are for focus. One adjusts the horizontal focus and the other the vertical. You need to alternate between them until both horizontal and vertical lines are as sharp as possible. Andy Cuffe

snipped-for-privacy@gmail.com

Reply to
Andy Cuffe

No monitor has ever had automatic focus.

This monitor's G2 is controlled through software, so there's no physical G2 control. See my other post about how to fix it without even opening the case. Andy Cuffe

snipped-for-privacy@gmail.com

Reply to
Andy Cuffe

Thanks, Andy!

Your advice fixed my problem !! That even without taking the cover off like you mentioned. Great !!

I won't like the day when this monitor pass away, since I like it very much. It has very good performance, like you probably know. By the way, do you have a service manual for it, or more advice regarding common faults etc ?

Thanks again, Andy!

Regards PAF

Reply to
powerampfreak

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