T42 screen goes black, ok after restart.

[bretddog]

Suddenly, yesterday, the screen on my T42 went black. I've made no hardware changes and no software changes/installs. The computer kept on working, which I know because I'm connected from other laptop to a software running on the T42.

Tried to twist, turn and push on the chassis/lcd, in case it's a bad connection, but doesn't make any difference. A restart is required, and then the screen is fine, for a while, now down to a few minutes only. Fan is running, tried to fix it at max speed, but doesn't seem to make any difference.

Any ideas what this may be, or if it's a known problem..?

[RealBlackStuff]

Either a stuck LCD On/Off switch (near the left-top corner), or more likely: a broken CCFL that only works while it is still cold.

[rkawakami]

Problem most likely is a worn-out backlight (difficult to replace individually) or a weak inverter board (easy to swap out). You might be able to get more runtime by turning down the brightness of the display.

[bretddog]

Thanks!

The lid-switch was helpful, by using it to turn the lcd on/off I can trigger it to turn on again, instead of doing a restart. But it doesn't act like the switch itself is the problem.

The brightness setting definitely impacts the behavior. It's 7 levels, and at two brightest it's on for only 5-10 seconds. On 5th and 4th it's on for 30 seconds and 2 minutes respectively, then a barely noticeable flicker for a few seconds before it goes dark. On level 1 to 3, I'm still testing (>30min), may last for a while.

So does that give any further clue?
I read somewhere that 95% of cases it's the CCFL, not the inverter. No idea if that's true. But I guess I'll try replacing the CCFL if that's the likely cause.

[rkawakami]

That's pretty much true but if it were me, given the age of the system I'd spend the ~$10 replacing the inverter with a known good unit first before committing time and money to replace the LCD panel. It's not easy to replace the CCFL as it's buried within the panel. Besides the danger in breaking the lamp, either the old one when extracting it, or the replacement when it goes in, there's always the chance that you inadvertently damage the LCD in some way. For simplicity, I'd rather replace the whole panel (or lid assembly, which will have another inverter in it already) with one that is known to work. Unless the panel is one of those that are relatively rarer or costlier (IPS, for example). Then I'd consider the cost/risk ratio in taking apart the panel. This is the boat I'm in as I have a couple of burned out A31p panels and some CCFLs waiting for me to dive in .

[goldap77]

Hi! Pls explain CCFL abbreviation; i ve bumped into similar bug with T43 LED going black , lid knob helps for 2-3 seconds; inverter has been updated ; what is to be checked further?

[RealBlackStuff]

CCFL = http://en.wikipedia.org/wiki/Cold_cathode

[rkawakami]

Welcome to thinkpads.com!

CCFL = Cold Cathode Fluorescent Lamp; the type of light bulb that is inside the LCD panel and gives off the white light needed to see the display. If you have changed the inverter and the panel still goes dark after being on for a few seconds, then it is assumed that the CCFL is bad. The easiest way to check this is to replace the panel with another one that is known to work. Usually it is easier to replace the whole lid assembly than it is to take out and replace the LCD panel by itself.

[bretddog]

.. It's not easy to replace the CCFL as it's buried within the panel. Besides the danger in breaking the lamp, either the old one when extracting it, or the replacement when it goes in, ...

Yes this seems like a somewhat delicate combination; not the easiest replacement, and the mercury vapor. Though I do enjoy a challenge..

My screen seems so far to be working fine on the lower half of brightnesses, so considering it's secondary tasks I'll put off the decision until it fails.

[topshot]

.. It's not easy to replace the CCFL as it's buried within the panel. Besides the danger in breaking the lamp, either the old one when extracting it, or the replacement when it goes in, ...

Yes this seems like a somewhat delicate combination; not the easiest replacement, and the mercury vapor. Though I do enjoy a challenge..

My screen seems so far to be working fine on the lower half of brightnesses, so considering it's secondary tasks I'll put off the decision until it fails.

If you have a 15" version (preferably IDTech mfg apparently), it's not too hard if you like a challenge and can solder. 14" is a big pain from what I'm told. Must be similar to some others I've done. My 15" T42p were a breeze compared to those.