Hello,
I am using Lenovo ThinkPad E550 for two years.
Few days back the backlight of laptop stopped working, When the laptop boots you can see windows logo and all if you look with a flash light and also if you connect it to external display then works fine.
I bought a new LCD third party panel but the backlighting is not working even on new panel.
Can anyone please suggest me what could be the real problem?
wrote:
Can anyone please suggest me what could be the real problem?
Welcome to the forum. Assuming that you've checked the cable between the panel and motherboard the most likely cause is a blown fuse. I don't think it's replaceable without specialized equipment. You may be able to "fix" the problem by running a jumper across the fuse. That said, I don't know exactly where this fuse is located or how it's labelled on the E550. Perhaps someone else will be able to post that information.
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No i haven't tested for faulty cable.
I thought that if cable was faulty then you shoudn't see anything on display.
How do i check whether cable is faulty? (And where to find new one?)
I meant check that the cable connectors fit tightly. That's a simple, if obvious, thing to check.
It's more likely that a fuse is blown. That could be expensive to repair. You might be able to find a used motherboard on eBay that's cheaper.
My comments are mine. I don't work for or speak for Lenovo.
Please do not send me PMs. Ask your question on this forum so that everyone can respond or learn.
Broken cable is not common unless there is physical damage. Besides the cable, there are 3 parts involved: the motherboard, the panel and the Hall sensor (lid closed sensor). I have not worked on that model so I am not sure where the parts are located. Motherboard problems are usually related to the fuse, but they don't blow for no reason. They are easy to blow while you are working on things, especially plugging and unplugging cables or screens. The fuses are usually very near the LCD connector. Most of the little parts on a motherboard are fuses, capacitors and resistors. On most machines the resistors are black; the capacitors are mostly brown, and the fuses are often white with metal bands at the end and maybe a single letter on top, denoting the capacity. You can test the fuses for open circuit with a meter, but if a fuse just blew out, there must be another underlying problem. The Hall sensor as a magnetic switch that occasionally fails. On most models, there is a little magnet in the palmrest that trips a switch in the lid (often on the side or near the microphone and camera). When you close the lid, the switch gets near the magnet and the backlight shuts off. I try to figure out where they are by sliding a little screw around on the palmrest until the screw jumps to the magnet.
Were you doing anything when the backlight stopped working?
Nothing unusual.
I just opened the lid and pressed the power button.
The screen lit up for some seconds and then the backlight stopped working that's it.
I think that there must be something with the sensor.
How do it test whether sensor is working fine ?
Hello,
I found the lid sensor, it is located near power button. When i moved a magnet around it the laptop goes to sleep mode. This means sensor is working fine.
Now either it is faulty lcd cable or fuse.
What should I check for first then?
Also for cable can we test with other laptop's cable or it has to be specific for E550 only?
