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Laptops manufactured by Dynabook (formerly Toshiba). Toshiba has since transferred 100% ownership of the laptop business to Sharp.

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Why is the blacklight not working after screen replacement?

I have a Toshiba R950 with a faulty LED blacklight. The screen is very dark and you can see text when you use a strong light. So it is a blacklight problem. I have ordered a screen from china, with a higher resolution, but same 40 pin and almost the same screen model number. The blacklight was working, but the screen was green and blurry. I swapped the china screen with the old one, the old one has still no blacklight. After swapping once again, the china screen also has no blacklight anymore! I have ordered the same screen as the original from the Netherlands, but it has also no blacklight. So I have 3 screens with no blacklight. What can be the problem? I think it is maybe the invertor, but that is mounted on the screen, so I don't know.

Thank you in advance.

Answered! View the answer I have this problem too

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@kevinb1012 it is possible that the screen with the " almost the same screen model number" has shorted out your backlight circuitry. Since it is an LED backlight there is no separate inverter. The driver and converter for the LED's are all part of the motherboard. You would need a schematic and layout for your specific motherboard. Take a good look at all the components on your board and see if you notice any obvious damage. Sometimes it helps if you post some images of both sides of the board with your question. Use this guide Adding images to an existing question for that. Even within the same model you may have variations on the motherboard. You need to identify that first. Bigger issue here is that you are dealing with a Toshiba. That company is as paranoid and secretive as Apple, maybe even more. Finding any schematic etc. is almost impossible.

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THe problem was the fuse on the motherboard. There were about 5 fuses on the motherboard, after testing with a multimeter, I concluded one was broken. I puta small wire above it, because these fuses are very difficult to get. The original screen is now working too! That's strange, because how can a fuse by itself get broken. But anyways it is working now. Thank you for your help.

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@kevinb1012 "possible that the screen with the " almost the same screen model number" has shorted out your backlight circuitry. " most likely the reason why "how can a fuse by itself get broken." Great that you got it fixed and best of luck to you!

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I have the same problem. I had a look at the motherboard, but did not find any fuse. where is it located?

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If I remember correctly it was on the keyboard side, but I am not completely sure. An easy wat to find it, is by using a multimeter. Search on the motherboard for small fuse boxes and use the multimeter on the 'beep stand'. If there is no beep, then you have probably the right fuse. Good luck

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i have a toshiba 55l7453D model all my backlightsa work been tested with backlight meter all led working fine but when turn of tv by plug our standby and turn back on nothing black screen but u can here and see pic in background give it a knock they come on after awhile they go off but sometimes stay on till u turn tv off again bit of a knock our wobble of tv come back on and works fine dont understand because all led work pleaae help

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