Laptop backlight stoped working again after shorting the fuse

Hi @aabi ,

You have to wonder why the fuse blew in the first place? Fuses blow for a reason

Did you replace the fuse or simply short it out? If shorting it out you may have damaged the backlight power circuit on the motherboard or in the display assembly as fuses are there to protect the equipment if a fault occurs

Usually, with the laptop turned on, the power to the backlights is on all the time and they are turned on and off in the display panel by a voltage signal being enabled/disabled on the backlight enable lead which is one of the wires in the video cable.

This wire connects to the motherboard controller chipset and there is also a connection from the lid switch as well. I think that the lid switch in your laptop is actually a sensor located on the power button board.

What is the model number of the motherboard, (printed on the motherboard itself)?

Knowing this will hopefully help to find the schematics for the motherboard. Search online for (insert motherboard model number) schematics.

The schematic will tell you exactly which wires in the video cable are used for the backlight power (if 40 pin connector then wires 38-40 but not always) and also the backlight enable lead, (this one can vary). It will also show which wire the lid switch connects to on the power button board cable.

If testing indicates a problem with the lid switch, then here’s the maintenance and service guide for the laptop, taken from this webpage. Go to p.56 to view the necessary pre-requisite steps and then the procedure to remove the power button board. Replacement boards are available online. Just search for 749650-001 to find suppliers that suit you best.