Question about IBM ThinkPad R40 2681

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Screen darkens intermittently without command

My screen will black out at will. The black out is not total, I still can see a faint goast image, and the curser is still operational. Is this a battery issue, or is it time to saay goodbye to my trusty laptop?

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Sounds like your backlight is going bad.

Posted on Jan 06, 2008


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I have lenovo 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.

Feb 10, 2013 | Lenovo G550 PC Notebook

1 Answer

We will get a black screen but still have sound.

Sounds like a main board that controls everything on the screen and then some.

Since a LCD do the flashlight test (what I call it) : darken the room as much as possible and with a flashlight and the set on look closely at the screen, see a very very faint image of the picture or not?

Dec 22, 2012 | Vizio 42 in. LCD TV

1 Answer

Can the lamp be replaced for a Polaroid TLX03210B

You likely have a LCD set there which may likely use a back light inside to light the image, get the room as dark as you can and with a flashlight illuminate the screen from a angle, with set on if you can see the faint image on the screen of the program you have a Backlight issue'

1. Voltage not there or not being switched on for backlight.

2. Actual back light bad.

If the image can be seen with a flashlight one of the above is the issue and your "picture will appear very faintly" also suggests this.

Dec 18, 2012 | Polaroid Televison & Video

1 Answer

My laptop boots up but the screen is blacl

Try connecting the laptop to an external monitor first. If this works, you can eliminate the Graphics chip as a source of your problems.
If it fails to work on an external, the graphics chip on the motherboard has possibly gone bad.

If it does work, you have 3 possible problems:

  • The VGA cable has been damaged (unlikely)
  • The inverter has gone, you can check this by seeing if you can see a faint image on the screen in a darkened room, if you cannot, probably the inverter is at fault and will need replaced
  • The backlight has gone on the screen, if you CAN see a faint image, then the screen is getting power but the lamps are not lighting, you will need to replace the screen of the laptop.

Jul 20, 2011 | Acer Computers & Internet

1 Answer

My hi grade laptop screen is not coming on

Try connecting this to an external monitor, see if it gives an image,if it does, you will need to check the inverter and back light of the laptop screen.
if it is the backlight at fault, you should see a faint image on the screen in a darkened room
If it is the inverter, the screen will remain black with no image.

Top replace the backlight, the screen itself must be replaced ( approx. cost £60.00 used)
Replacing the inverter approx cost £10.00.

neither are difficult jobs, but the cost may outweigh the value of the laptop if it is the backlight.

Knowing Hi-Grades though, the above points are academic. I'd be 90% certain that the graphics chip has failed ( no picture seen on external monitor). this is very common with hi-grade laptops, as the cooling to the graphics chip is very poor. Sadly in this case, you will need to replace the motherboard, the cost of which will certainly not be worth it

Jul 18, 2011 | Computers & Internet

1 Answer

My LG monitor blacks out intermittently when warm, I have tried it on another computer so it is a fault with the monitor. It blacks out every few seconds, sometimes it takes longer. It is 2 years old.

after blackout, check the screen as that. look in to the monitor in side angel,
and if you can see darken live image in that and its working. in that condition, your
LCD panel is working and the problem is no light.
in that case you need to repleace or repair the " inverter unit " in that monitor.
that unit makes the high voltage for back light.

after blackout , you cant see any darken image like as that, and or totally power
goes off , that is different problem. for solve that need advance trouble shooting
and can be need advance repair.

Jan 03, 2011 | LG Flatron W2243SPF Widescreen LCD Monitor

1 Answer

Acer Aspire 5100 Laptop Screen Works Intermittently

Since you have video with an external monitor your lcd panel is going out.This is not hard to repair only costly

Apr 06, 2010 | Acer Aspire 5100 Notebook

1 Answer

Black screen on my notebook gericom webgine xl per4mance??? The sistem is operating but can;t see anything!

Can you see any image in a darkened room - best to try right at start up when the logo appears. If you see a faint image it means your back light or inverter is out. OR it may be that the lid closed sensor switch is jammed which is telling the laptop to turn off the backlight. Look near bottom of the screen for a small bump sticking out - this will correspond to a switch on the laptop base. Make sure the switch moves up and down. Some switches are on the hinge itself.

Nov 18, 2009 | Computers & Internet

1 Answer

Laptop has power but screen remaining blank

Screen backlight/inverter may also be out - see if you can see a faint image in darkened room or by shining a flashlight into the screen

Apr 11, 2009 | Acer Aspire 5315 Notebook

1 Answer

Faint screen image

when you first power on using lower right (power) button, wait 6 seconds for the intro screen to finish. The upper left (up) button increases screen contrast. Hold this one down for a few seconds and the screen should darken. The middle left (down) button decreases contrast.

If this doesn't work, try turning off by holding the power button.
Hold down upper left AND upper right while turning unit on. This initiates diagnostic mode and contrast is darker by default. Bottom of screen is a button test area which darkens a symbol for each successful button press. Use it to diagnose a button problem. Turn off power and on again to leave diagnostic mode.

I wish you success playing with the Etrex.

Dec 07, 2007 | Garmin eTrex GPS Receiver

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