Backlight issues

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#1 Post by **GomJabbar** » Sun Mar 04, 2007 2:23 pm

Today I am really beginning to have some backlight issues with my T42. I can be browsing, typing or whatever, and suddenly the backlight goes out. I can see the display very very faintly from the overhead lighting. Moving the TrackPoint or pressing the Fn button has no effect. If I press Fn + F3 while in this state, I can see even the very very faint display disappear. If I then press the Fn button, the display lights right back up to normal for a few minutes.

What is the consensus? Is this the CCFL backlight or the inverter that is going out? I suppose it could be a software or other hardware issue, but that seems less likely to me. I have been noticing for the last several months, some pink especially at the bottom of the display, and even more so when the brightness is turned down. Today I have had the LCD brightness set to 7 (maximum) and have been on AC power when the backlight kept turning itself off. I also rebooted once, but that didn't make a difference. FTR, my T42 is about 2 years old, and the warranty is expired.

Just now, I set up my S-Video to output to the TV. When the display went dark on the LCD, the TV still was showing my desktop. If I press Fn + F3, then the desktop disappears from the TV as well. After this, pressing Fn lit the display back up and the desktop was again showing on the TV.

Website · #2 Post by **tfflivemb2** » Sun Mar 04, 2007 3:42 pm

Actually, given the symptoms, it could be either one (CCFL or Inverter)....I know that doesn't help.

I would try replacing the inverter first, since it is generally cheaper and easier to replace. The other benefit to replacing the inverter first, is that if it isn't the inverter, you can always resell it and get most of your money back.

#3 Post by **rkawakami** » Sun Mar 04, 2007 3:43 pm

Sounds like the power to the inverter is getting turned off or the inverter itself is shutting down for some (unknown) reason. Seeing how the inverter is fairly cheap, I'd go for swapping it out with another unit.

edit: Ah, beaten by Steve again. Really have to finish my posts all in one session and not be bothered by outside forces... This time my daughter wanted me to hear some strange noises in the backyard...

Leikeze Ajnin · #4 Post by **Leikeze Ajnin** » Sun Mar 04, 2007 4:07 pm

I had a similar problem with a T-30 a few months ago. It turned out not to be the cheaper and easier part to replace - the inverter - but the backlight itself had up and died. Not saying you shouldn't try the inverter first, but if it's like the problem I had it more likely is the light itself.

#5 Post by **tomh009** » Sun Mar 04, 2007 4:17 pm

A failing backlight normally also shows an additional symptom: a pinkish hue when you first turn on the display.

If you are not seeing this, the chances are that it's the inverter, which is inexpensive and easy to replace.

#6 Post by **GomJabbar** » Mon Mar 05, 2007 9:24 am

Well I am seeing some pinkish hue at times.

Here is some more info. I booted up into my Vista partition with the same results as in XP, so that pretty much rules out a software problem. Last night I took out the inverter card and used some electrical contact cleaner on the two plug connections, then reconnected. No change (at least I didn't break anything - yet).

This morning while I was using my T42, I was only getting a minute or two before the backlight would shut off. I have been on AC power with the brightness level set to 7 (maximum). After I was having so much trouble this morning, I decided to go the other way and set the brightness level to 0 (minimum). Since I have set it to zero, my backlight has not turned off in the last couple of hours.

#7 Post by **tomh009** » Mon Mar 05, 2007 1:07 pm

With inverters available on eBay for under $10, I think it's still worth a shot -- unless your are certain about the pinkish hue on startup.

Here is one:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0088637727

#8 Post by **rkawakami** » Mon Mar 05, 2007 1:52 pm

GomJabbar wrote:Since I have set it to zero, my backlight has not turned off in the last couple of hours.

That may point to the inverter drawing too much current and shutting down. I know that there are several "thermal fuses" on the T23 motherboard. I would assume that the T4x are designed similarly. Basically they look like the greens ones in this picture:

http://www.globalsources.com/gsol/I/Res ... 279017.htm

Now, the problem could be the inverter itself or the CCFL requiring more power to keep it lit brightly. Since it's infinitely easier to change the inverter vs. the backlight, that would be my plan of action.

#9 Post by **GomJabbar** » Mon Mar 05, 2007 7:30 pm

Another update. This evening, now it began turning off every couple of minutes with the brightness level set to zero. I turned the brightness up to level 4, and it seems to be working fine again. I think (hope) that the problem is with the inverter board, and not a motherboard problem. I kind of doubt the CCFL backlight is the culprit with these particular symptoms.

#10 Post by **GomJabbar** » Tue Mar 06, 2007 8:25 am

Today I ordered an inverter card (supposedly new) from CompuNet Solution for $24. With shipping and tax it comes to $36. I am having it shipped to the company warehouse. Hopefully I can pick it up in a timely manner. I'll report back once it's installed and tested.

zone · #11 Post by **zone** » Tue Mar 06, 2007 9:38 am

I had similar symptoms with my A31p, few weeks ago display started to flicker and within couple of hours went black, I can see desktop icons windows etc under beam of light but F7 brightness controls etc doesn't help, external display works fine, have to say that I didn't have any pink yellowing indicator that display is at end. So, I got new inventer but no change. Well, my next try will be CCFL exchange since this is much cheaper than hunting 15" UXGA display on ebay, and LCD part in display is working . Also second hand display may be temporary easier fix but as it seems it's only question of time when CCFL in used display will die... seems that CCFL lasts cca 3 years under heavy use.

#12 Post by **tomh009** » Tue Mar 06, 2007 10:13 am

GomJabbar wrote:Another update. This evening, now it began turning off every couple of minutes with the brightness level set to zero. I turned the brightness up to level 4, and it seems to be working fine again. I think (hope) that the problem is with the inverter board, and not a motherboard problem. I kind of doubt the CCFL backlight is the culprit with these particular symptoms.

Given that an external display still works, I think it's very unlikely to be a motherboard problem.

NS · #13 Post by NS » Wed Mar 07, 2007 10:42 am

Gomjabbar,

That is not a motherboard problem for a 99.99999% confirmation. It cannot be the backlight CCFL tube because your thinkpad is only 2 years old and even if you can use it for 24 hours daily for 2 full years, the CCFL won't die off yet. It took around 4-5 years of continuous daily use (more than 10 hours daily) for the CCFL tube to die. <--my gf thinkpad is the evidence...

<Just joking> Your thinkpad LCD wants a good rest after all the year long moderation duties from you...

#14 Post by **GomJabbar** » Thu Mar 08, 2007 10:45 pm

Tonight I got the new inverter card and installed it. It's no better than the one I took out. On full brightness the backlight shuts off in less than a minute. At mid brightness it seems to work OK.

Website · #15 Post by **tfflivemb2** » Thu Mar 08, 2007 11:04 pm

I am leaning towards the CCFL, given that the new inverter hasn't helped.

This is where working on laptop LCDs can be really tricky...even though it is now most likely the CCFL (given the pinkish hue and the inverter not helping), there is still the possibility that it could be the systemboard. I know that several people have said that it can't be the systemboard, since the external monitor still works....HOWEVER, the issue could be that something on the systemboard is preventing the inverter from getting enough power to keep the CCFL running properly....and possibly even creating the pinkish hue, similar to a "brown out" when there is minimal power.

As for the comment above about it not being the CCFL because it is only two years old....that is not necessarily the case. Bulbs can have defects that cause their lives to be shorter than normal.

NS · #16 Post by NS » Fri Mar 09, 2007 1:17 am

Ok, i am sorry for missing out on the facts about defective CCFL tubes...

Steve has made a good point. Thanks.

#17 Post by **GomJabbar** » Fri Mar 09, 2007 8:30 am

I just ordered the CCFL backlight from lcdpart.com. I wish I could be more optimistic about it fixing the problem.

Website · #18 Post by **tfflivemb2** » Fri Mar 09, 2007 8:41 am

GomJabbar wrote:I just ordered the CCFL backlight from lcdpart.com. I wish I could be more optimistic about it fixing the problem.

yeah, sorry that it is such hit or miss diagnostics. I think that Ray suggested somewhere (possibly here, but I am too lazy to scroll down and look), but if you have a voltmeter, you could probably check the power coming in and out of the inverter to see if the problem is before or after the inverter. As to what the numbers should be, I haven't a clue.

#19 Post by **rkawakami** » Fri Mar 09, 2007 12:47 pm

No, I retracted that suggestion (measuring the output voltage of the inverter) after I almost blew up an inverter. I may have shorted the two output pins together, but when I tried measuring the output voltage with a DVM, I got a nasty "snap" and the smell of burning plastic (the clip I was using melted).

After some further investigation I found that the loading of the output voltage by the CCFL is not constant (i.e., like a fixed value resistor). Special equipment is needed to measure the inverter's output voltage.

As far as the input voltage, I did not try that.

#20 Post by **GomJabbar** » Fri Mar 09, 2007 1:13 pm

rkawakami wrote:...when I tried measuring the output voltage with a DVM, I got a nasty "snap" and the smell of burning plastic (the clip I was using melted).

No doubt

Below are the specs for the CCFL for my LCD panel:

lcdpart.com wrote:Part Number - MS20290
CCFL Voltage - 725
Watts - 2.85
Starting Voltage* - 980
Intensity ( Cd/m2 ) - 38,000

*Starting Voltage: Typical Vrm

#21 Post by **GomJabbar** » Mon Mar 12, 2007 7:37 pm

This problem is getting worse day by day. I won't be surprised if the backlight becomes basically useless in another a day or two. I am 'hoping' that I can get to the company warehouse sometime this week to get the new CCFL tube I ordered and see if that fixes the problem. Trying to view text on a cheap 13" TV with a composite video connection through a composite/S-Video adapter to the S-Video port on my ThinkPad is the worst.

EDIT: Now, my backlight only stays on a minute or two at a time.

1ravendog · #22 Post by **1ravendog** » Wed Mar 14, 2007 11:14 am

I am at same point with T42/UXGA. Please keep us posted on your replacement experience.

Best,
Mark

#23 Post by **GomJabbar** » Wed Mar 14, 2007 11:25 am

Will do.

I won't make it to our company warehouse (where the new CCFL backlight shouid be waiting) until sometime next week. In the meantime I am hoping I get a chance Friday to buy a 15" LCD TV/Monitor (1024x768 with VGA port). Best Buy supposedly has one for $159 this week - in store only. This would upgrade my existing TV, and give me a fallback option. My existing setup is barely usable. Being able to zoom up several levels in Opera is the only thing that keeps me online.

EDIT: Well it took 10 days from the start of my problems with the backlight to no backlight at all.

#24 Post by **GomJabbar** » Tue Mar 20, 2007 7:03 am

OK, I received the new backlight yesterday. Man, this thing is tiny! A standard #2 pencil lead is thicker. I measured the diameter with a set of vernier calipers at 0.075" (1.9 mm). That's just over 1/16" in diameter. The length is about 11".

Getting to the backlight, I removed the entire display lid, necessitating the removal of the keyboard, palmrest, and keyboard bezel. The HMM said there would be some T7 torx screws holding the palmrest on models with the 802.11ab WLAN card, but there weren't - only phillips. Removing the display lid from the T42 was not overly difficult.

My problems began when trying to deal with the backlight itself. I broke the old one trying to remove it. I also broke one of the leads trying to remove the backlight reflector assembly. The single wire soldered on each end of the tube, was soldered right next to the glass on the tube I had removed. First I had to slide the silicone caps off the end of the tube and down the wire, then unsolder the leads (wires) from the tube.

The instructions said to solder the leads 2-3 mm from the end of the glass with a 25W max soldering iron, 4 seconds or less. This I did; I bent the lead in a short U shape and slid over the wire end of the tube, soldering it in place with the lead coming out at a right angle. This was a mistake. I had difficulty getting the silicone caps slid back fully onto the tube. I should have soldered the leads in-line with the wires extending from the ends of the tube. Next I had difficulty fitting the slightly longer tube and reflector assembly back into the LCD display. I installed and uninstalled several times, breaking one of the leads again, necessitating another solder job to the tube. I also damaged one of the silicone caps, so I used one I ordered along with the backlight. Now when I put the backlight reflector assembly back in, the wires to the inverter were too short. I had to find a length of similar diameter wire to splce in. Finally, after several more attempts, I got it back together, but the backlight was slightly too long, and I kind of forced it all together and held it this way with the High Temperatire Metalic Tape that I also bought with the baclklight.

Are you still with me? After this long and sorted tail, I still do not have a working backlight. It could be that I damaged something in the wiring to the backlight. I don't think I physically broke the backlight, but it is a possibility. I am tempted when I get home, to remove the display connector from my wife's T42 and plug in my display for a test to see if it will light up or not. I am not sure when I will be home to do this though.

To sum up: I would not recommend doing this yourself unless you are quite handy with tools and handling small pieces. My fingers are kind of fat because of the work that I do, and that does not help any when dealing with tiny backlights, tiny wires, and tiny screws. I learned from this experience, and would probably have better luck next time. If I could afford to spend the time to send it in for backlight replacement, I would seriously consider that route next time. I would not hesitate to replace an entire display lid however. If I find out my backlight job was successful when I test it with my wife's T42, then that would mean that I need a new system board. I sure hate to junk my favorite laptop.

#25 Post by **GomJabbar** » Sat Jul 21, 2007 6:09 pm

Well to cap this off, I finally got around to purchasing a used T42 display lid complete on ebay for $100 + $17 for S&H and Insurance. The display was marketed as a SXGA. My existing display was XGA. What I received was XGA.

The backlight on the new display works fine (I am glad it wasn't the motherboard). I was hoping for the higher resolution of SXGA+, but it is still just XGA. Oh well, I'll just settle for what I got and be happy.

The posts below by larrys gave me hope that I would only need the display...
http://forum.thinkpads.com/viewtopic.php?t=44264

Now I have restored factory contents and am setting up this T42 for my daughter. It will be replacing the old 600E that she has been using. That 600E was my first laptop.

mientras · #26 Post by **mientras** » Sat Aug 25, 2007 1:41 am

Going back to the original post, I have the exact same problem. When it works the screen is bright and shiny but it goes dark randomly and more often. When it first comes on, it exhibits the pink color. AFter reading the messages, I am going to try for a new CCFL. Any suggestion for an experienced repair shop in Los Angeles that can change the backlight?

I have a T42 with a 15" SXGA+(1400x1050)TFT LCD.

Thanks

#27 Post by **GomJabbar** » Sat Aug 25, 2007 5:27 am

I saw these guys on the internet, but I have not used their service.

http://www.moniserv.com/doc/laptopscreen.html

Robbyrobot · #28 Post by **Robbyrobot** » Sat Aug 25, 2007 6:12 am

I saw these guys on the internet, but I have not used their service.

Is that a realistic service at those prices?

#29 Post by **GomJabbar** » Sat Aug 25, 2007 6:26 am

The price seems reasonable to me. The job is somewhat labor intensive and requires a certain amount of expertise and finesse.

I happened to choose a different route and bought a used display lid complete on ebay for $117 (shipped). It was advertised SXGA, but turned out to be XGA. I kept it anyway as my existing display was XGA. IIRC, a new XGA display runs about $250 US. A SXGA+ display no doubt costs more.

mientras · #30 Post by **mientras** » Sat Aug 25, 2007 11:32 pm

My 3 year warranty expired a couple of months ago, but I paid with American Express which extends warranty coverage by a year. I will try to see if Easyserve will give me an estimate for this repair as well as a very noisy fan and check coverage with AMEX.

Thanks for the tips.

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