After 30 to 45 minutes display showes 2 or 3 verticle color bars. Each bar has multi stripes of color and is about 1 to 2" wide. Turn off tower and wait 30 minutes and problem repeats after turn on and 30 minutes. Have replaced monitor and do not have any problem.

perform a soft reset. Turn off the TV, unplug the connector from the socket, and wait 2 minutes. ...

conector ribins on lcd driver board needs cleaning.

need to find out if the issue is with the display, power chord, vga cable, vga card or the connectors...

1. disconnect all the cables from the LCD or the monitor, now just connect the power chord and power on the display and now see if it gives you any display

2. Try swapping the power chord with the tower (if its a desktop).

3. Try and change the VGA or the HDMI cable to test if the issue is with the cable or not, (the cable that usually goes from the back of the display to the tower)

If the issue is with video card then launch PSA on your Dell machine and perform LCD bist test.

To launch PSA:

1. Restart the system.

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2. At the Dell logo screen, press <F12>.
Note:
Some systems do not have an F12 key, to access the boot options you have to press the <0> (zero) key at the Dell logo screen.
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3. At the One Time Boot menu, press the <Down> arrow key to highlight Diagnostics, then press <Enter> to begin PSA.

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4. Write down any error codes listed.


Steps to perform LCD BIST after PSA is launched:

1. Watch the screen and listen for the color bar test prompt tones emitted by the PSA Diagnostics. If the screen is visible, one will see the PSA diagnostics draw a series of multi-colored bars across the screen. When completed, a prompt asking if the pattern was seen appears, accompanied by a brief series of tones.

2. Press <N> or wait approximately 30 seconds to fail the color bar test.

3. Watch for the LCD BIST color generation and listen for the beeps every 2 seconds that indicate LCD BIST is running.
LCD BIST runs for approximately 20 seconds, then stops. The 3-3-3 or 3-3-4 error code is then displayed when the LCD BIST is complete. If LCD BIST does not initialize, then the system may not have been upgraded to PSA version 3019.

Have ou gone into your menus. Into troubleshooting, then image quality.
You will want to run both the eliminate light stripes and eliminate smears procedures. that will purge the print head, blow air through the jets and hopefully resolve the problem. I do believe the 8550 has a Jet Substitutin procedure where you can do a workaround and make other jets make up for the light areas.
here are some directions, Will forward more

1. Press the [Up] or [Down] arrow button on the Control Panel to select [Troubleshooting] on the Display Screen, and then press the [OK] button.
2. Press the [Up] or [Down] arrow button to select [Print Quality Problems], and then press the [OK] button.
3. Press the [Up] or [Down] arrow button to select [Troubleshooting Print Quality Page], and then press the [OK] button.
4. Evaluate the 'Light Stripes Test' page for missing printhead jets, such as missing Cyan, Magenta, Yellow or Black color bars. The 'Light Stripes Test' page is the last page of the Troubleshooting Print Quality Page that printed.
   
   WARNING: To avoid injury, do not touch the sharp metal strip attached to the clear rubber wiper blade in the Maintenance Kit.
   
   
5. Use a clean lint-free cloth or a new paper coffee filter to gently clean the maintenance unit's clear rubber wiper blade, use only a wiping motion across the entire length of the wiper blade, and then empty the waste tray. A dirty maintenance kit wiper blade can cause white lines and weak or missing printhead jets.





6. Repeat step 3 to reprint the Troubleshooting Print Quality Pages. If there are no missing or partially missing color bars then the print quality problem has been resolved. If there are missing or partially missing color bars then the printhead cleaning procedure will need to be performed. Continue with the next section.

To clean the printhead using the basic eliminate light stripes procedure:

1. Press the [Up] or [Down] arrow button on the Control Panel to select [Troubleshooting] on the Display Screen, and then press the [OK] button.
2. Press the [Up] or [Down] arrow button to select [Print Quality Problems], and then press the [OK] button.
3. Press the [Up] or [Down] arrow button to select [Eliminate Light Stripes], and then press the [OK] button.
4. Press the [Up] or [Down] arrow button to select [Basic], and then press the [OK] button. The printer will perform a head cleaning, which will take about five minutes. The printer will then print a cleaning page and a light stripes test page.
5. Repeat steps 1 - 4 one more time. If there are no weak or missing jets then the print quality problem has been resolved. If there are still weak or missing jets after two basic light stripe cleanings, continue with step 6.
   
   NOTE: Do not try the Advanced Eliminate Light Stripes Cleaning mode without performing two basic cleanings first.
   
   To clean the printhead using the advanced eliminate light stripes procedure:
   
   
6. Press the [Up] or [Down] arrow button to select [Advanced], and then press the [OK] button.
7. Select the missing jet color and number. If necessary, check the light stripes test page to determine the color and jet number of the missing jet.
   
   NOTE: Only perform the advanced light stripe cleaning once. If weak or missing jets still persist, continue with step 8.



8. Print the Troubleshooting Print Quality Page. Evaluate the Light Stripes Test page for missing printhead jets, such as missing Cyan, Magenta, Yellow or Black color bars. If necessary, perform the basic eliminate light stripes procedure one more time. If the Advanced Eliminate Light Stripes procedure does not resolve the weak or missing jets, perform the Enable Jet Substitution Mode. See the Related Items below.

I believe that this could be a type of "burn in". If you watch anything with a black stripe on the sides or bottom of the screen often, then this could be the problem. My suggestion is to watch things that have no black side bars for a while (>week) and see if this eliminates the problem.
Good Luck!!

Check the connections on the flat cables to the screen. Be sure first to disconnect the power supply from the x and y sustain boards before you disconnect any of the flat cables.you will burn the cables from the stored energy in the power supply, also check cables on c boards at bottom of screen. If this does not fix probably bad panel.

The screen does not work properly .Ribbon wire fails.

1. try connecting laptop to an external monitor and check if this vertical dark gray bar appears. if yes it means video is the problem. you need to boot in safe mode then uninstall the video driver. boot to notmal mode then download and install the latest video driver. if still same problem then replace video card. if video is built in with motherboard you need to replace motherboard.

2. when the vertical dark gray bar did not appear in the external monitor then it means issue is with the LCD panel. Do this turn off laptop. press and hold D key then press Power button at the same time or Press and hold on the Fn key then Power button check if the test will run. Color displays full screen when you keep pressing on N key when the colors appears check the vertical dark gray bar if still exist in the test, this means LCD panel and LCD cable needs to be replaced.

This is power supply problem.
1. First u replaced the power out put capacitors , 6V, 12V, etc.
2. cheak the diodes.

Sounds to me that you have a bad connection/wire to the CCFL bulb on that side of the display. Should be an easy fix, do it your selfer thing.