T43 backlight problem

[lagged]

My T43 has developed an annoying problem. When I close the lid the the backlight and lcd turn off like normal, but when I open it, the backlight only comes on for a second. The lcd works fine however. I then have to manually press the lid switch a dozen or so times until the back light stays on. Each time I press it it will flash for a quick second.

Is this a problem with the switch or the backlight? Any ideas of how to fix it?

[richk]

The first thing to try is to remove the bezel behind the keyboard and see if the button there is binding. (you ned to look at the maintenance manual to see how to remove this. You take off the keyboard and the touchpad first. (If you have a 15" screen, the touchpad and bezel are one piece.) Then you can attach the keyboard and start it up and try the switch on the LCD cable (under the switch on the bezel) to see if that's sticking.

[rkawakami]

Welcome to thinkpads.com! (finally uncloaked huh? )

If the lid switch does not prove to be the problem, the next (cheapest) thing to check/swap would be the inverter board. I'm assuming that when the system is first turned on from a cold start, that everything works normally and then sometime after the system is "warmed up", that the backlight has trouble staying on. If so, you could have a thermal problem somewhere (motherboard, inverter, backlight). As the inverter board is relatively cheap and easy to get to (refer to the HMM for instructions on how to remove), I'd try that first. The other "free" thing to try is re-seating all of the connections between the motherboard and LCD.
ref:
T43 (1871, 1872, 1873, 1874, 1875, 1876) HMM
T43 (2668, 2669, 2678, 2679, 2686, 2687) HMM

Just thought of another thing you might be able to try... Cycle through the LCD/external monitor settings with the Fn+F7 key sequence. Does the backlight have a problem turning back on with that?

[mitchellst]

Did your LCD have a pink tint to it when it was first turned on? Since you didn't mention it, I doubt it. If so, then it's your LCD. If not, then my money's on the inverter.

[lagged]

Thanks for the help guys; I'm going to try to clean out the little switch per your instructions. If its anything more than that I still have on site warranty service. Wish me luck!

[Jim Olson]

Mitchellst, can you elaborate on the problem that causes the fluorescent back light to come on with a pink tinge for a minute or so? My Thinkpad does that.

The back light color (and brightness) eventually reaches the normal bright white, but it takes a couple of minutes.

[GomJabbar]

Hopefully you do not have the beginnings of a similar problem related in the following thread and links inside. This has happened to several of us. At least you still have your warranty to fall back on - I did not.

http://forum.thinkpads.com/viewtopic.php?t=47751

[The Spirit of X21]

Mitchellst, can you elaborate on the problem that causes the fluorescent back light to come on with a pink tinge for a minute or so?

Jim, this happens when the fluorescent bulb in the LCD is near the end of its life. You can fix this either by replacing the bulb (very hard, but cheap - $10) or replacing the LCD (easier, but much more expensive - $100-200)

[Johan]

... Any ideas of how to fix it?

Check the thread: LCD CCFL Backlight Repair/Replacement - I'll fix it for you! - I'd certainly consider this offer, compared to start messing with it on my own (because I haven't tried it, and would be afraid of damaging something!).

Best regards,

Johan