P991 problems

Question

My Dell/Trinitron Ultra scan P991 monitor has developed a number of problems over the last few months:

1. Faint blue screen background, cannot be eliminated with brightness/contrast controls.
2. Faint Vertical retrace lines visible.
3. Display washed out at high brightness setting and colors are not intense.

I tried the "Color Return" function from the monitor built-in tests with no visible result.

In order to get a useable display I had to set the contrast at maximum, brightness at minimum, and "sRGB" selected and turned on. Any other color setting gives me an unuseable display.

A replacement monitor works ok which would eliminate the video card.

No problems with other monitor functions, convergence, geometry, de-gaussing, etc. The monitor has been in use for an average of 4 hours a day for 5 years.

Is there any hope for this monitor? Is there service information available? Any help would be appreciated.

zonie

zonie776 · Answer

It appears that my brightness problem is caused by the CRT G2 voltage being too high. I measured 700V. According to the service date it should be 560V.

While doing some research, I came across Sony DAS (digital alignment software) which is a windows program used to change parameters in the P991 EPROM including adjustment of the G2 voltage.

Anyone know anything about the DAS software? How to use it, how to connect to the monitor, tech data for the software, etc?

zonie

spikeage · Answer

I too have been suffering with high brightness on my P991 monitor.  Good news!  The Color Reset function only works after the monitor has been operating for about 30-45 minutes....the so called 'warm up' period.  After my wife played a game for 45 minutes, the reset color function in the monitor's OSD menu became available.  Using this function, TOTALLY restored the Brightness and Contrast range to 'normal'.    Once I further adjusted the Brightness and Contrast controls just slightly for my preferences, (48 and 51 respectively), my P991 was looking as good as it did when I bought it, about 5 years ago I figure.  Be patient...and try this solution.  It worked perfectly for me!!!   Spike

zonie776 · Answer

Spike,

Thanks for the response. I have used the color reset function (too often apparently) and you are
correct, it TOTALLY restores contrast and brightness.

However, there is a catch. As the monitor gets older you need to do the restore more often.
Every time this function is used, Sony, for some strange reason, increases the G2 voltage a little.
After a number of color resets G2 gets to a point where you'll end up with the high
brightness problem. The G2 is controlled by the internal micro processor rather than an
electrical adjustment. The proper way to lower the voltage is through software update.

If you ever get to this point, take a look here:

http://www.geocities.com/gregua/windas/

I initially changed a resistor in the G2 circuit but it wasn't a satisfactory solution. I then used the
windas program and that solved my problems.

If you have som experience with electronics, a schematic for the P991 is available on the
net . I don't have the address handy - Google should be able to find it for you. Just keep
in mind, there are lethal voltages inside the monitor.

I posted my solution on another Dell thread about P991 problems. Should have posted it
here also. Sorry 'bout that.

zonie

Monitors

P991 problems

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