Boots with Dark Screen

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Alb-Oz
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Boots with Dark Screen

#1 Post by Alb-Oz » Mon Feb 22, 2010 12:35 am

This is most likely not just an R32 thing, so read on.
I know this can be a bad inverter or lid switch, but it acts very odd.
when I boot my R32 it would almost always boot with a dark screen
in XP. I moved to Vista and it worked normally for a long time,
then went back to booting with a dark screen again (i.e. shadow LCD).
sometimes you can see a dim light at the bottom then just goes dark.
sometimes it would light up on its own after the F12, F1 BIOS at start-up
screen was all timed out, and Windows shows up on screen.
It will just work normally for a long time, and then go back to dark almost every time.

to get the screen to light up, one of these would most likely work:
hold the PC upside down (sometimes works)
close and open the lid (sometimes works)
unplug and plug-in the 16volt power plug (most times works)
hold down FN key and tap screen brightness keys up or down (most times works)
that last one is the oddest one of all.

restarts work normally and after lid closed, wakes or restarts normally. (most of the time)
it acts more like the screen thinks it is in closed lid or sleep mode than anything else.
I have heard that if the inverter has been replaced, it needs an update of some kind
to tell the firmware the new inverter was installed, or it won't see the inverter at start-up.

any Ideas?

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Re: Boots with Dark Screen

#2 Post by tcone » Wed Mar 03, 2010 9:00 pm

If a faulty inverter is replaced, then no update of whatever is needed. Just replace it and the backlight will work as expected.

If your screen doesn't have a reddish tinge when you power your thinkpad on, then it's very likely that your inverter is faulty or that you have a loose connector. A red tinge would be an indicator for a dying backlight.
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Re: Boots with Dark Screen

#3 Post by RealBlackStuff » Wed Mar 03, 2010 9:09 pm

Take it apart, and reseat the LCD cable on the motherboard as well as on the back of the LCD.
Also reseat the inverter. Check the lid-switch as well.
You may just need a new LCD cable, if that switch is on the cable...
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Alb-Oz
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Re: Boots with Dark Screen

#4 Post by Alb-Oz » Tue Mar 23, 2010 12:19 pm

Took it apart, and reset the inverter plug. will have to Check the lid-switch when I have time.
I think the lid switch is a SPDT and one led is not making contact (dirty?)
I am able to recreate the dark screen 90% of the time after a boot up, by pushing the lid switch
in, and it will not light the screen when I let the switch back up. the only way to relight the screen
is to push the screen brightness keys down and up. touch the lid switch, and it's back off.
I think the switch functions to tell it the lid is closed, but does not tell it when the lid is reopened.
I'll take it apart when I have less need to use it. just incase I damage something.

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Re: Boots with Dark Screen

#5 Post by rkawakami » Tue Mar 23, 2010 1:20 pm

Alb-OZ wrote:<snip>... unplug and plug-in the 16volt power plug (most times works)
hold down FN key and tap screen brightness keys up or down (most times works) ...<snip>
I'd have to agree with tcone; try replacing the inverter. If the backlight (aka, CCFL) is not showing any obvious signs of a pink/red tint on power up, then you could have an intermittent inverter board. If turning up (or down) the brightness with the Fn key combinations makes the light come on, without touching the lid switch, or if changing the laptop's power condition also makes the CCFL turn on, then I would suspect the inverter board. An inverter board for the R32 appears to run around $10-$15 on eBay and is easy to replace.

I suppose that a dirty switch could be causing your problem but usually if you toggle the switch several times very quickly, it tends to clean itself. The switch can be cleaned using an electrical contact cleaner spray but you have to be very careful and select one which does not attack any of the plastics that might be used in the switch or on components in the surrounding area. This is assuming that there's holes in the switch housing which allows the cleaner to enter. You can always replace the switch but you have to have some good soldering skills to remove the old one and install the new without causing any damage (I'm assuming that the switch is of the surface mount style). Not sure where the switch is mounted; some systems can have the switch on a smaller PC board, generally the one which have the I/O ports soldered on it, and it may be easier (but costs some more $$$) to simply replace the sub-board. Other systems may have the switch mounted directly on the motherboard. Then you have to decide if it is cost effective to buy an entire motherboard to fix this problem.

Either that, the backlight is getting harder to start up. In which case, an inverter replacement or switch cleaning/replacement may not help. The pink/red tint definitely points to an aged backlight and generally means that the lamp is on the way out but it's also possible to have a "normal" light that's having some trouble turning on.
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