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Using the Monitor Self-Test
The monitor provides a self-test feature that allows you to check whether your monitor is
functioning properly. If your monitor and computer are properly connected but the monitor
screen remains dark, run the monitor self-test by performing the following steps:
1. Turn off both the computer and the monitor.
2. Unplug the video cable from the back of the monitor. To ensure proper Self-Test
operation, remove all digital (white DVI connector) and analog (blue VGA connector)
cables from the back of the computer.
3. Turn on the monitor.
The floating dialog box should appear on-screen (against a black background) if the flat panel
display cannot sense a video signal and is working correctly. While in self-test mode, the power
LED remains blue. Also, depending upon the selected input, one of the dialogs shown below will
continuously scroll through the screen.
Troubleshooting steps
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Summary of Contents for Dell U2421M
- Page 1 Troubleshooting steps Using the Monitor Self-Test The monitor provides a self-test feature that allows you to check whether your monitor is functioning properly. If your monitor and computer are properly connected but the monitor screen remains dark, run the monitor self-test by performing the following steps: 1.
- Page 2 4. This box also appears during normal system operation, if the video cable becomes disconnected or damaged. The monitor will enter Power Save Mode after 5 minutes if left at this state. 5. Turn off the flat panel display and reconnect the video cable; then turn on both the computer and the flat panel display.
- Page 3 Your monitor has a built-in diagnostic tool that helps to determine if the screen abnormality you are experiencing is an inherent problem with the monitor, or with the computer and video card. To run the built-in diagnostics: 1. Ensure that the screen is clean (no dust particles on the surface of the screen). 2.
- Page 4 8. The test is complete when the white screen appears. To exit, press the Button 4 again. If you do not detect any screen abnormalities upon using the built-in diagnostic tool, the monitor is functioning properly. Check the video card and computer. Common Monitor Issues What You Common Symptoms...
- Page 5 Pixel that is permanently off is a natural defect that can occur in LCD technology. For more information on Dell Monitor LCD screen has Missing Pixels Quality and Pixel Policy, see Dell Support spots site at: www.dell.com/support/monitors Cycle power on-off. ...
- Page 6 Do not perform any troubleshooting steps. Visible signs of Safety Related Issues Contact Dell immediately. smoke or sparks Ensure that the video cable connecting the Monitor monitor to the computer is connected Intermittent Problems malfunctions properly and is secure.
- Page 7 Perform monitor self-test feature check to determine if the intermittent problem occurs in self-test mode. Perform monitor self-test feature check. Ensure that the video cable connecting the monitor to the computer is connected Picture missing properly and is secure. Missing Color color ...
- Page 8 Product Specific Issues Specific What You Possible Solutions Symptoms Experience Image is centered Check the Scaling Ratio setting in Image Screen image is too on screen, but does Setting OSD. Reset the monitor to Factory Settings. small not fill entire viewing area ...
- Page 9 setting to match your Graphics Card by following instruction found in section "Connecting the Monitor For DP MST Function". When choosing DVI-D/DP/DVI/HDMI mode, the Auto Adjust function will not be available. USB Issues Specific What User Experience Possible solution Symptoms ...
- Page 10 Reboot the computer. Sound bar Issues Common What You Possible Solutions Symptoms Experience Turn the Power/Volume knob on the Soundbar clockwise to the middle position; check if the No power to power indicator (Blue LED) on the front of the Soundbar —...
- Page 11 Turn the Power/Volume knob on the Soundbar counter-clockwise to a lower volume setting. Clean and reseat the audio line-in plug. Troubleshoot the computer's sound card. Test the Soundbar using another audio source (i.e. portable CD player). ...
- Page 12 Test the Soundbar using another audio source (i.e. portable CD player). Cardreader Issues Problems Cause Solution A. Right-click My Computer on the desktop, and then click Manage. Under Computer Management, click Desk Management. B. In the list of drives in the right panel, right-click Removable Device and then Drive letter is not...
- Page 13 Reboot the computer. Quick Tips content is self-published by the Dell Support Professionals who resolve issues daily. In order to achieve a speedy publication, Quick Tips may represent only partial solutions or work-arounds that are still in development or pending further proof of successfully resolving an...
- Page 14 As such Quick Tips have not been reviewed, validated or approved by Dell and should be used with appropriate caution. Dell shall not be liable for any loss, including but not limited to loss of data, loss of profit or loss of revenue, which customers may incur by following any procedure or advice set out in the Quick Tips.