Computer monitor all black but power is on.

It sounds like you are experiencing an issue with your DiamondPoint V50Lcd monitor where the screen is displaying as black. Here are a few things you can try to troubleshoot the problem:

1. Check the power. Make sure the monitor is turned on and receiving power. Check the power cord and outlet for any issues.
2. Check the cables. Make sure the cables connecting the monitor to the computer are securely plugged in and in good condition.
3. Check the computer. Make sure the computer is turned on and functioning properly. Try connecting the monitor to a different computer to see if the issue is with the monitor or the computer.
4. Check the monitor's settings. Make sure the monitor is set to the correct input source and that the display settings are properly configured.
5. Restart the monitor and computer. Try restarting both the monitor and the computer to see if this resolves the issue.
6. Check for updates. Make sure you have the latest driver and firmware updates for the monitor. You can check for updates on the manufacturer's website or through the monitor's update feature.

If you have tried these things and the screen is still displaying as black, the issue may be with the monitor itself. In this case, you may need to have the monitor serviced or repaired by a professional.
I hope this helps! Let me know if you have any other questions.

Your monitor have board problem.Need for repair and troubleshoot.Maybe a deffective power supply.

At this point I believe there are failed caps in your monitor.
http://www.badcaps.net/forum/showthread.php?p=73310

This is very common in all LCD monitors. Did the tech just push the power switch off and on?
From my experience at fixing broken monitors of all brands, I think it is the power supply problem.
http://s807.photobucket.com/home/budm/allalbums
http://en.wikipedia.org/wiki/Capacitor_plague
http://www.badcaps.net

You can get second help from repair shop also.

un plug the monitor cables power cord everything turn off the computer the reconnect everything power back up turn on the monitor should work then

Try the fuse on the monitor power cord, and if this does not cure, you will have to get another monitor....pretty good prices on ebay!

Bad caps in the power supply, common problems. See examples here: http://s807.photobucket.com/albums/yy352/budm/Viewsonic%20V912B/

Same problem - unplug both computer and monitor - hold power button for monitor for 15-30 seconds...then power it back on and then power on the computer. Seems from other sites there is a power issue with the monitor - this worked for me.

Same here- I understand that the capacitors are bad and need to be replaced. I am going to undertake it myself. Radio Shack sells them.

bad capacitors on the power board internal to the monitor they need to be replaced.

Hi,
First, verify the monitor is functional.
Monitor STFC (Self Test Feature Check)
Turn off the monitor
Plug the monitor power cord directly into the wall socket to remove any
surge protectors or APCs from the troubleshooting equation
Unplug the monitor video cable from the back of the computer
Turn on the monitor
The floating dialog box should appear on screen against a black background.
If the issue appears during the STFC, the monitor is defective.
What are the results please?