LCD backlight problems

[MikeG]

I hope you'll bear with a long post; I've tried to include all the necessary background info up front. Some of the questions may be dumb, but I hope those at least are straightforward and answerable with short phrases.

I have a hand-me-down T21 with 14.1" display, not sure if it's XGA or SXGA but from the reading I've done so far, I don't think that matters in my situation.

The display works, but there is no backlight (I can clearly see displayed text and graphics, they're just too dim to read comfortably.) Before it died completely, I would get occasional red-hues when I booted the machine up or the screen came back on after power-management-turn-off. It went away in less than a minute and I didn't notice any other significant change or deterioration in image quality apart from a very slight dimming in the couple of years I've had the computer. FWIW, I use it basically as desktop and open/close the lid once a day at most. I never noticed any change in the display when I moved the lid slightly (to get at something behind it on my desk, for example) Currently I'm using it with an external monitor which works fine.

I've tried turning the LCD on a few times (Fn-F7) since it died yesterday and a couple of those times there was a brief flash of white light in the bottom right corner of the screen. It wasn't enough to illuminate the whole screen in any color, red-hued or otherwise, just a brief triangular flash of pretty clear white light. Oh, and I've tried adjust everything I could find to adjust, so I'm confident I didn't somehow accidentally turn the brightness all the way down.

From the initial Googling I did, I was kind of relieved to think I'd discovered it was the inverter card or maybe the cable, but after looking at all of the LCD posts here, I'm starting to think it may well be the CCFL itself. I'm reasonably good with my hands and have done some miscellaneous maintenance in desktop cabinets, but I've never opened up a laptop and am not eager to mess around with the guts of the LCD screen itself. But since I'm not working right now, money is definitely an issue and I think I'm confident enough to risk not paying someone else to do the work.

Would anyone care to venture an opinion as to the most probable cause of the problem? CCFL, inverter, or cable?

Any which way, I figured I'd have to open it up, so I downloaded the HMM and started reading. I was pretty dismayed to see that according to IBM, you have to basically pull the whole freaking computer apart even just to get to the inverter card much less anything behind the panel. I realize this may be a really dumb question, but is this really true? You can't take apart the lid without removing the hard drive. keyboard, fan, etc., etc. first? Another possibly dumb question: I don't carry the machine around much at all, so how important is it really not to reuse the nylon coated screws as the manual warns?


Lastly, a bottom line question: if I were to attempt any repair (inverter, cable, CCFL itself) and royally screw it up, am I likely to render the machine completely useless? If worse came to worst and I end up with a topless laptop with the LCD cable hanging free, would the machine likely continue to work with an external monitor or will an unterminated cable leave it inoperable? I'm weighing the option of just using it as I am now, with the external monitor, but after using the LCD screen for so long, this [censored] CRT is making my eyes hurt!

Thanks for any guidance anyone can offer!

Mike

[redsb3]

Given your description, especially the red hue, and the fact that it will briefly flash on occasionally, given all those "conditions", 99 out of a 100 times it will be the CCFL that has died. Inverter and cable are "cheap" fixes if you care to try and be the one of a hundred. Opening up a display is not for the faint of heart, or the impatient. Also, I usually ruin about 1 out of every 10 and I know what I'm doing. Sometimes for no reason, after you replace a CCFL, you get what I refer to as "watermarks"on the screen. I think it occurs from flexing the backing next to glass, but I'm still not positive. It is a not an easy task, nor is finding the actual lamp itself. Its tough finding somebody, other than a wholesaler, who will sell you only one lamp. I think you best bet is to pull the display out and see who made it, then go shopping on eBay for a replacement. 14" displays can usually be had for around $100 or so. If you do attempt this and ruin it, you will not destroy the notebook and will still be able to connect it to an external monitor, I do it all the time for testing purposes. Anyway, good luck.

[krosenstein]

Re: replacing a CCFL -- see:

http://forum.thinkpads.com/viewtopic.ph ... ea80f741b0

[MikeG]

Thanks to both of you. I saw the post about replacing the CCFL, I wouldn't have even dreamed of trying it before I saw that, so thanks to you too, James!

Just so I'm 100% clear on this, if I decide to open up the display, I should follow the HMM instructions to the letter? That's what has me a little nervous. Since the display is useless to me as it is, I'm not so much worried about physically damaging it as I am about messing something else up in the process of yanking and more importantly replacing what seems to be just about everything but the motherboard to get to the screen. <sigh>

[Jim Olson]

My bet is that the problem is not the CCFL (lamp) but the inverter that drives it. The clue was the red hue before it died. This module is easy to replace and is available all over the internet for about $40. Be careful not to purchase someone else's dud.

I found that the going price for LCD panels for T-2x machines is $300. These are pulls from dead machines with scratches on the polarizer and hours on the CCFL. They might be cheaper on E-Bay but with no guarantee of functionality.

When I went looking for an all-new LCD panel I found none that were affordable. You'd trash the computer before paying that much.

The inverter is located under the bottom edge of the frame that surrounds the LCD. The frame comes off with three screws located under sticky black dots adjacent to the hinge. Pull down on the frame to disengage it from the top.

The inverter has two connectors that pop apart with a small screwdriver.

The entire replacement might take me sixty seconds. A novice might take fifteen minutes tops.

Yes, the external video port should function even when the inverter or CCFL is busted. How you'll get it to the external video mode without the display functioning is another question...

[MikeG]

Thanks, Jim. That gives me some hope so I guess I will try the inverter before deciding whether to try anything further. Especially if I don't have to worry about removing (and more importantly replacing) all those other components first!

As for using the external monitor with a nonfunctional/non-existent onboard screen, I'm not really sure, but I think it's sensing and defaulting to the attached monitor when I boot up. But then, if the LCD weren't there at all, I guess maybe I'd get a BIOS error when I tried to boot up? Dunno, guess I'll have to burn that bridge if/when I get to it.