New screen installed but not working

posted in: Screen, Troubleshooting | 213

If you installed a new screen into the laptop and for some reason it doesn’t work, there may be a few  things you could have done wrong.

Lets figure out step-by-step how to troubleshoot and  and fix the problem.

First of all, I assume that your new LCD is compatible with the original one. If the screen looks identical, it doesn’t exactly mean it’s compatible. Double check the compatibility between the original and new LCDs.

Troubleshooting LCDs with CCFL (backlight lamp)

The old style screens have a backlight lamp inside and require an inverter board which is usually mounted on the lower part of the display assembly, as you can see on the following picture.

New LCD screen not working

On the following picture you can see how the screen connected to the laptop. Also, check out this display diagram.

The video cable routed from the motherboard to the display through one of the hinges. Somewhere close to the hinge, the cable splits. The wider end connects to the screen (supplies data signal) and another one to the inverter board (supplies power for inverter).

Check cable connections

If your new screen lights up but has no image make sure the video cable plugged correctly. It’s possible that during the reassembly process you accidentally pulled the cable from the connector.

Reconnect the cable, secure the connection with sticky tape and test the laptop. There is a chance that now the screen will work properly.

Improperly connected cable

The video cable has to be seated properly, all the way down into the connector.

Properly connected cable

Some older LCDs have very thin pins inside the video connector as it shown on the following picture.

Take a look inside, make sure there are no damaged (bent) pins. It’s possible that you accidentally bent them while trying to plug in the cable.
You can straighten bent pins with a very small screwdriver. Be careful, they are very fragile.

Fortunately, most newer LCDs have a different type of connector, without any pins inside.

Pins inside connector on LCD screen

OK, you have reseated all cables but it still doesn’t work. What’s next?

If your original screen was cracked but undamaged areas still work and show some image, you can use it to test the laptop.

Disconnect the new LCD and install the old damaged one back in place. If the old screen still works but the new one doesn’t, your new screen is defective. Send it back to the seller for a replacement.

Here’s another scenario. The new screen kind of works. You can see a very faint image but there is no backlight.

Disconnect the new screen from the inverter board and plug in the old screen instead (I assume it has working CCFL), as it shown on the picture below. If the original screen lights up, apparently the new screen has defective backlight lamp.

Old screen lights up

 

Troubleshooting LED-backlit LCDs

Newer LED-backlit LCDs have only one cable connected to it. This cable supplies data signal and power for LED backlight.

LED-backlit LCD

If your new screen doesn’t work, check the connection first. Make sure the cable seated properly, all the way down into the connector.

You can test the computer with the old, partially working screen, as we did earlier. If the old one still works, but the new doesn’t, your new screen is defective or not compatible.

Also, you might be interested in how to troubleshoot bad video.


213 Responses

  1. up date on my toshiba A65-s126, laptop repair. removed the dc jack i had installed, cleaned the landing area. found that the small trace on the under side, inside left solder point, had made contact. an this was causeing the system to turn off. now up to needing password. any help here?

  2. cj2600

    @ PAUL,

    Did you make sure that your new screen is compatible with your Sony laptop? If you installed a wrong or incompatible screen it’s possible you fried the motherboard.

  3. PAUL

    I replaced a sony VPCEB4JOE screen. The backlight on the new screen does not come on, however the old one now doesnt come on either.

    is this a defective cable to the screen from THE MOTHERBOARD .IVE TRIED A NEW CABLE AND STILL SAME PROBLEM

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