Thinkpads Forum

How do you tell if a dead screen is an LCD failure, blown backlights, or bad inverter? Trial and error? I have a 600X with a cracked working screen and parts left over from a full lid replacement from another 600X.

A couple of easy and free things to try:

- Carefully push down on the lid switch a couple of times. Those switches tend to break and if bad, will cut off the power to the backlight.

- Shine a bright light upon the screen when it is supposed to be displaying something. If the pixels are active then it could be the inverter or backlight. If no pixels are active, try the Fn+F7 key sequence a couple of times to make sure that the LCD is in the active mode.

http://forum.thinkpads.com/viewtopic.php?t=48910

If the neon bulb flashes on for a brief time when the system is powered up but no light is emitted from the backlight, then I'd say the backlight is dead. If there's NO activity from the neon bulb, then that's an inverter, cable or motherboard issue.

The best method, but not necessarily the easiest, is to swap in a complete lid assembly which is known to work. That will eliminate/identify the motherboard as being the source of the problem. The cheapest parts to individually replace are the Sub Card (where the lid switch is located) or the inverter.

Both motherboards are fine, I'll do the LCD swap with the cracked one. Probably a bad inverter, I believe I did the flashlight test and had a good panel.

Did the LCD swap tonight. Used a known good inverter and the light just fades away. I will tear apart the cracked LCD panel for the backlights just to see how hard that swap will be. Case was full of dust bunnies and cat hair...even found a loose screw floating around there.

I have two good 600Xs now, tore apart the lcd panel and pulled the top wire right off the backlight. Soldered it back on and it works great, the pain of assembly is over and I have a working display.

Nice work! Congrats on the successful repair.

Phil.