I have lenovo g550...my screen flickers in every 5minutes...
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.
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