T40 Display won't work on battery power

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lavinbuk · #1 Post by **lavinbuk** » Sun Dec 10, 2006 10:13 am

Out of the blue, the display on my T40 doesn't work on battery power. It works perfectly fine when running on AC, but when I pull the plug to battery the display goes dim to almost virtually dark. I've check the power management settings and the display is set to a go a bit darker to save power, but not totally dim.

Any ideas?

nodus · #2 Post by **nodus** » Tue Dec 12, 2006 6:12 am

sounds vaugely like a inverter+older battery issue to me. They really dont like to get under a cirtain voltage and if the battery is older it may have fallen under that threshold, slowly killing the inverter. You migh be able to check with a multimeter. If you want a example of of a inverter dieing plug a screw in type florecent blulb into a light with a dimmer switch. It will be dead in a week. (the screw in type have a inverter built in to generate the high voltages for florecents) sorry for the spelling its 3 am here.

lavinbuk · #3 Post by **lavinbuk** » Tue Dec 12, 2006 2:43 pm

Thanks. The battery is less a replacement of the original - less than a year old and from IBM itself. I sure hope that isn't the cause since the machine went out of warranty three months ago.

If anyone has other thoughts they'd be much appreciated - I'm fairly sure I'm not capable of changing the inverter myself (it that is even possible).

#4 Post by **GomJabbar** » Tue Dec 12, 2006 5:26 pm

http://forum.thinkpads.com/viewtopic.ph ... 365#229365

EDIT: Do you have the green battery icon in the notification area at the bottom right? If so, left-click on it and choose Battery Information > Battery Health... What is displayed? If you do not see the icon, go to Start > All Programs > Access IBM > and launch Battery MaxiMiser Wizard. When the screen shows up to display the icon, check the box.

RRHODY · #5 Post by **RRHODY** » Tue Dec 12, 2006 7:44 pm

I don't have a T4X, but in ThinkPad Configuration for my T30 there's a LCD icon that lets you change the display brightness from "NORMAL" to "HIGH" while on battery. Try changing that to high as well as the other battery checking suggested.

lavinbuk · #6 Post by **lavinbuk** » Tue Dec 12, 2006 7:49 pm

Battery is totally healthy. New (unfortunate) development is that now the monitor goes dark even when running on AC (just did it now). If I unplug the machine and plug it back in the monitor fires up again.

Very disturbing...

#7 Post by **rkawakami** » Tue Dec 12, 2006 7:59 pm

lavinbuk wrote:I'm fairly sure I'm not capable of changing the inverter myself (it that is even possible).

It is possible to change yourself, just grab a copy of the Hardware Maintenance Manual from here:

T40/T41/T42 HMM

If it's like the T23 (I've never torn a T4x apart), then all you need to do is remove the LCD bezel (several small screws around the edges of the lid) and remove the inverter card. They should be available on eBay or you could ask here in the Marketplace forum. Be sure you get the correct one (14.1 and 15" panels appear to use different inverter cards).

lavinbuk · #8 Post by **lavinbuk** » Tue Dec 12, 2006 9:14 pm

Thanks for the great advice Ray. Is there a way for me to confirm that the problem stems from the inverter before I purchase a new one? Some sort of diagnostic tool maybe?

#9 Post by **GomJabbar** » Tue Dec 12, 2006 9:16 pm

Check out the forum thread I posted above for a link to get it repaired at a reasonable price - that is if you uncomfortable with doing it yourself.

EDIT: If your backlight was showing pink - especially at dim settings, I would tend to suspect the CCFL (backlight). From your description, I would tend to suspect the inverter. I admit, I am not an expert on this subject, but I base my speculation on what I have gleaned from reading some related posts in the past. The company I linked above will fix one or both problems for a flat rate.

#10 Post by **rkawakami** » Tue Dec 12, 2006 9:28 pm

About the only way I know of verifying that the inverter is doing its job is do hook up a voltmeter to the output pins of the inverter card. I believe that it should be outputting a couple of hundred volts AC so I would be VERY careful if you choose to do this. I have not attempted this feat as I'd just as soon as change the card and see if the problem goes away. I've been "tickled" enough times playing around inside of TVs many years ago to say that I've had my share of amps flowing into (and out of) my body.

Instead of unplugging the AC adpater, try either the Fn+F3 combination to turn off the display (then press any key to turn the display back on) or the Fn+F7 sequence three times it switch between the external monitor and LCD. Both of these will cut off power to the inverter and then re-apply it. See if that "wakes up" the inverter/backlight.. Problems with the light in the LCD panel can be the inverter, the lamp in the display panel, the LCD ribbon cable or power/signal problems from the motherboard. Generally, a sudden loss of the light points to the inverter. If your lamp has been pinkish/reddish upon power up, that's usually a sign that the backlight is reaching the end of its life. Inverter cards are fairly cheap on eBay so I'd start with that. If that doesn't fix the problem, then I'd consider a backlight replacement or entire LCD panel swap.

(And I was typing this up and getting interrupted by my boss, GomJabbar jumped in there and beat me to it....)

lavinbuk · #11 Post by **lavinbuk** » Tue Dec 12, 2006 10:24 pm

Wow. Again - thank you guys for the great advice. The Fn-F3 test did the trick -- after turning the LCD off and waking it up, the display "awoke" (of course, it dimmed again a few seconds later). Similar things happen with Fn-F7 and I suspect the reason I can get a lit screen by unplugging the AC and then plugging it back in is because its cause the inverter to do the same thing.

So, inverter it is! I'm going to look into replacing it myself - many thanks...

T40 Display won't work on battery power

T40 Display won't work on battery power

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