When switched on the dark black covers 70% of the screen and after 20 minutes comes to normal. why, and what to do

There is a very good answer to your monitor issue found here:

http://www.fixya.com/support/t467725-samsung_lcd_monitor_syncmaster_203b

Failing Inverter An inverter, typically found inside a laptop computer, consists of a small board, which has impregnated electronic circuits stamped on it. Inverters look like thin boards about the of two sticks of chewing gum. The inverter and its bulb control the intensity of the liquid crystal display, which lights the screen monitor. The computer can control the output voltage of the inverter and either lighten or darken the screen. A special type of inverter can adjust the brightness of the screen by using an internal sensor to judge the room brightness, and then adjust the screen accordingly. Failing inverters give off some specific warning signs, which can be recognized by observing different screen characteristics.

Short Intermittent Display Upon turning on the laptop, the screen flashes on in the normal mode for a short period and then blinks to black. A very faint image appears in a dark background, which will be very hard to see almost invisible. After shutting off the laptop and restarting, the same mode occurs, where the screen appears normal for a few seconds then fades to black. This condition points to a failed inverter. To confirm this, plug in an operational external monitor; if the external monitor functions, the inverter has failed. b> Total Blackout with Ghost image b> The laptop turns on, as indicated by the power supply button, but the screen comes up black. The screen comes up black after restart. You might be able to detect a very dim or ghost-like image on the monitor. When you plug in a known functioning external monitor, the external monitor operates normally. This mode of display indicates a failed inverter. b> Long Term Periodic Operation b> With this failure mode, the laptop screen illuminates normally upon start-up and remains that way after several minutes, hours or even days, until it goes very dark again. Brightness controls or restoration attempts do not work. Most often, the screen will function normally with a computer restart, but will eventually return to black. Faint ghost images might appear, as seen in the total blackout mode. b> Dark With Color Variation b> Upon computer start-up, the monitor shows black or dark gray, accompanied by very faint images. The screen might have an intermittent color change, or remain on with a non-standard color variation, like pink or red. b> Auto Control Switch b> If the screen appears black, with no faint or ghost images, look for the lid switch near the back hinge. The switch, when depressed with a closed lid, shuts off the computer and monitor functions. Sometimes the switch becomes stuck in the closed position, disallowing the computer and monitor to turn on when opened. Pushing the switch manually several times can often free it up. If the switch tab has broken or jammed inside the case, it needs replacing. b> Loose Connection In this mode, the display looks normal upon start-up, but tapping the side case of the computer turns the screen black. More tapping results in the screen functioning normally then cutting out again. This condition points to a loose wire connection from the inverter to the LCD backlight lamp, or the video cable. The connectors can be accessed by removing the monitor bezel screws and pulling the plastic retainer off. Both connectors can be cleaned and refitted.

hi

try rebooting the system (i think its F8, to get to SAFEMODE) . in DESKTOP , right click and go to PROPERTIES, go to SETTINGS, go SCREEN RESOLUTION and take the arrow to the left ; set to 640x800 and and take the color setting to 256 drop down . hopefully this works after rebooting the system. if it doesnt, it may sound like the inverter card may be bad (PC bourd that connectes to the screen : this requires a service technician)

good luck !

Turn the computer on, and take it into a totally-dark room.
Do you see a very-dim, but otherwise-normal, image?
If so, then a $20 part, the "inverter", has failed.
Take the computer to a qualified technician, for replacement of that part.
You'll probably have to pay $50 to $70 for "labour" to disassemble the LCD screen,
replace the part, reassemble, and do some testing.

Connect it to another monitor,and see if it comes on. Your screen may be damaged.

That Probaly Means Your ******* Kid Jerked Off All Over The Monitor *******

Connect an external monitor to your laptop and power it up, if you see the normal Windows images then the video card and laptop is OK and the problem is definitely the backlight.

If you see a very dim image or black screen or flicking image on the LCD screen it means you have a backlight problem.

The buzzing sound is most likely the inverter problem.

Dim image and/or dark display on the laptop's LCD screen indicates a faulty LCD backlight and it could be the inverter that supplies high voltage to the CCFL lamp or it is the CCLF lamp is nearly burnt out or burnt out, most likely this is the case.
The inverter can be replaced easily but the CCLF lamp is more time consuming and requires soldering skills.
Check out www.lcdparts.net for parts, repair service and DIY info.

you mean few second the monitor goes in black. then its come. if it happen, it is ok

Correct ! One set is for RGB focus and the other set is for
RGB screen voltage............................T.

Pix looks like a light pipe issue, inside the Light Engine. as far as the shutting down, could be a bad fan causing the grinding and when stopps the DMD turns the set off.