No backlight on T500 and green LED status lights not working

[marlar]

The backlight on my T500 has stopped working. It's completely off, but I can vaguely see the screen contents by the help of a bright flashlight.

Additionally, the green LED indicators below the LCD are off except the bluetooth indicator.

It first happened a couple of months ago, but it started working again after a few days. Now it seems permanent, though.

Googling the symptoms tells me it could be the fuses or the LCD cable. Given that it stopped working and came back again, it's probably not the fuses. More likely, it's the cable or connector.

Still, I want to check the fuses. But where are they? I have removed the palmrest and the keyboard, but I can't locate the fuses.

Could somebody point me to where the fuses are? And also how to check the cable?

Here is a picture of the my Laptop with keyboard removed:
https://www.dropbox.com/s/h2b3whyigff5q ... 5.jpg?dl=0

[wileE]

fuses here: http://thinkwiki.de/W500_Sicherungen T500 is the same

There is also a fuse on the LED/inverter board. Next to the connector, marked F1.

Did you have any problems with the screen backlight before it went comletely dark?

[jaspen-meyer]

Have you tried reseating the LCD cabel at each end?

[Neil]

The number one suspect in my mind, based on your symptoms, is the LCD inverter. They are relatively cheap, and fairly easy to swap out, so not a bad place to start.

[marlar]

Thanks for replies!

Did you have any problems with the screen backlight before it went comletely dark?

No, one day it was just dark. No weird colors or stuff like that.

Have you tried reseating the LCD cabel at each end?

No, not yet. Actually I am in doubt how to do that. Do I have to remove the motherboard completely? And how do I dismantle the display? (can't find any screws).

Edit: I found the screws hidden behind six caps.

The number one suspect in my mind, based on your symptoms, is the LCD inverter. They are relatively cheap, and fairly easy to swap out, so not a bad place to start.

Would that also explain the missing indicators (except Bluetooth)?

Is it possible to test if the inverter is functioning?

[Neil]

Would that also explain the missing indicators (except Bluetooth)?
Is it possible to test if the inverter is functioning?

The indicator lights are actually on the inverter board. And the inverter is what supplies high voltage power to the CCFL. Not much one can do other than try another inverter. Unless you discover a loose connector on the inverter. Might just get lucky and fix it without any new parts.

[wileE]

And how do I dismantle the display? (can't find any screws).

Edit: I found the screws hidden behind six caps.

Consult the HMM before you grab a screwdriver: http://download.lenovo.com/ibmdl/pub/pc ... 630_04.pdf