Apple 23" HD display screen is black, power is on... All wires are connected. The computer is booting up fine. The monitor light is on. The monitor is remaining black. This has never happened before. Any Answers????????

Sometime the cross-talk of signals is caused by the wiring behind the computer, touching. Separate the wiring.

The only way to test is to use a known working power supply or known working cinema display with the parts you already have.

http://tim.id.au/laptops/apple/displays/cinema_hd_display_23.pdf

Yes. Any TV/video repair store should have a qualified technician. Or, contact Apple, and find the nearest "authorized' service-outlet to you.

have it service with registered technicians

eht coil generator which generates power for backlight tube is damaged change it

I have an older 20" display. I have had this same problem on occasion, and coincidentally, just experienced it again this morning. It seems to occur after I do an OS update. I powered down the computer, disconnected the display, reconnected by pushing firmly into place, then powered up. The flashing stopped and the display works fine. You might have a different problem, but that simple solution worked for me.

thats supposed to mean theres a faulty powerbrick, however i have the same problem on mine and replacing that didn't solve it

damn gay i got t is 23 apple screen for 14month and it has a black screen now :( .. what can i do to fix this .?

Sounds like the 90w power adaptor. This has happened to my 23" Apple monitor several times. (I'm on my third 90 watt "brick"!) It seems to happen after about one year of use. All you can do in the meantime is never shut down or let the monitor go to sleep.