Project Report: Replacing LCD Backlight

[Jim Olson]

This long-winded posting descrives my effort to replace the LCD backlight in two T-2x series Thinkpads from which I want to get another year’s usage. I'm waiting for a T-42 that offers an external DVI video port.

Getting replacement CCFL lamps is the key to this task. You can get CCFLs from several vendors but the best one hands-down is:

MoniServ, Inc.
28971 Hopkins St.
Hayward, CA 94545
Attn: Benson Hue
(888)785-7288
<moniserv.com>

I paid $10 apiece for the lamps plus shipping. Buy one more lamp than your actual needs because you’re guaranteed to break one during the installation process. They are only .080” in diameter and fragile as heck.

MoniServ does not keep a chart of CCFL type vs. Thinkpad model. You need to disassemble the Thinkpad and determine the LCD panel type and, most important, measure the length of the CCFL. MoniServ's not keeping a CCFL look-up chart annoyed me until I realized that IBM used multiple LCD vendors for each model of Thinkpad. In fairness to MoniServ, they couldn’t keep track of all the combinations of vendor, display size, and IBM model.

My T-21 had a 14.1” Hyundai-branded display that used a 290mm long CCFL. I was tempted to purchase a slightly shorter CCFL but I’m glad I didn’t. Matching the glass capsule length exactly is key to the lamp’s proper mounting in its saddle.

It takes seven screws under nine black sticky dots to remove the LCD display from the Thinkpad cover. Another four screws internally give you access to the teeny metal reflective channel that houses the CCFL. Pull the black frame around the CCFL downward toward the Thinkpad's panel hinge to disengage the frame at the top close to the latches.

Try not to destroy the molded silicone boots on the ends of the CCFL because they serve two roles: minimizing corona from the high voltage and providing “motor mounts” to support the CCFL in its reflective channel.

The notes in the shipping carton from MoniServ mention the importance of not stressing the leads on the CCFL. This is very important. Even with careful handling I injured the glass seals on the ends and started again with a fresh CCFL. Sliding the silicone boots back on the capsule is half the work to reassemble the display. My CCFL even had silicone donuts on the tube mid-span to hold it away from the metal channel. It took a magnifying glass to locate them.

The entire process took about three hours because I moved cautiously. It in the end it yielded an LCD that is only tad brighter than when I started. The LCD is still miles from the sparkling brightness that I remember when the Thinkpad was new. The color temperature is still low. White areas in the displayed images don’t have the crisp bluish-white color that I always notice on new LCDs.

Suspecting that the LCD might be plagued by low inverter voltage, I swapped the inverter with a known good one from another Thinkpad with excellent display brightness. There was no noticeable improvement in either color temperature or brightness.

Question to my educated readers: Is it possible that the optics in this LCD have components that have darkened or discolored with three years of usage? The UV light boiling off the CCFL lamp must be substantial. Is that UV severe enough to darken the polarizer film over the display? (MoniServ offers to replace polarizers for about $100).

I’d appreciate any feedback on these comments although I’m finished with this ill-considered refurb project. I’ll call Bill Morrow today about getting a new T-42. Opening an LCD is not a project for the timid. The panels are literally 0.25" thick--something that's not apparent from the Thinkpad's construction.

I’m a practicing electrical engineer who’s used a soldering iron every work day for 30 years. This job pushed my substantial skills to their limit.

The LCD described here was the 1024x768 one. I tried to replace the lamp in another T-21 that had the nifty 1400 x 1050 pixel LCD but gave up midway through the job. The lamp in that Hitachi-branded display is not accessible without detaching some microscopic flex circuit board connectors and disassembling the optics entirely.

“UNCLE”, the engineer cried wearily. With this posting my job is done. Thanks to Bill Morrow for a great forum.

Jim Olson
Fountain Valley, CA

[Leon]

Thank YOU for a wonderful post that will be valuable to many users for years to come. Welcome to our forum. Please come back and participate often!

[daeojkim]

WOW... This is agood information but it sounds like it is not a plug and play type of fix for novice.
Nevertheless this will a lot of people an option to fix their backlight.

Welcome to the forum.

[JHEM]

“UNCLE”, the engineer cried wearily. With this posting my job is done. Thanks to Bill Morrow for a great forum.

Thanks for that excellent synopsis of your adventure and welcome to the Forums.

Just as an FYI, I never pursue a backlight replacement without changing the inverter as well! I would posit that a new inverter might restore the "sparkling brilliance" you so fondly recall.

Regards,

James

[krosenstein]

Jim -

To extend the life of the CCFL, does it make any sense to set the screen so it will automatically turn off after specified, or does the increase in the on-off cycles offset any potential benefit?

[jpfsanders]

I definitely have to look for another laptop... this sounds way too scary for me

Anyway a great post!

Well, I guess is time for me to buy a brand new Txx, for me any cheap Thinkpad will do as I do not require much power... how good are the latest celeron models????

[Leon]

Welcome to the forum! None of the T Series have Celeron.

Check Bill's page (thinpads.com) for some good deals!'