Troubleshooting and Fixing a Blank LCD Screen
on your IBM ThinkPad notebook computer

After having spent most of the past 11 months using an external monitor because all I could see looking at the LCD panel on my IBM ThinkPad T42 laptop computer was a blank screen, it appears I have successfully corrected the problem by replacing the LCD panel. Since my research on the Internet indicates that a blank LCD panel is a common problem with ThinkPads, but that this symptom may be the result of a number of various causes, I offer the following information to those who may be experiencing a blank LCD screen on their ThinkPad—to the end that, maybe, they won't have to spend all the time I did groping for the solution, going down dozens of dead-ends.

"LCD brightness" setting causes LCD screen to go blank

Although comments and suggested solutions on the Internet indicate that there are various causes for ThinkPad LCD screens going blank, in my particular case, it was the "LCD brightness" setting that triggered the screen to go blank. (And I would like to say "Thank you" to a few now unknown souls whose random comments on the Internet led me to focus on this as a possible cause.) If the LCD brightness was set at high (or 7), the LCD panel would blink off almost immediately. If the LCD brightness was set at low (i.e., zero), the screen might stay on for one to two hours before blinking off (although it was a little difficult to read, being so dim). I also found that the screen stayed ON longer in the morning upon being booted up, after the computer had been off overnight. However, once it did blink off that first time, it did not stay on as long thereafter. [For whatever relevance this may have on the following discussion, I'm running Windows XP, SP-3.]

Once the screen blinked off, it could be refreshed by pressing Fn+F3 (turning off the "monitor"/screen) and then pressing any key to turn it back on. Likewise by pressing Fn+F4 (to cause the ThinkPad to go into sleep mode) and then pressing Fn (to wake it up) caused the screen to come back ON.

On the ThinkPad T42, the LCD brightness setting is manually controlled by pressing Fn+Home (to increase brightness) or Fn+End (to reduce brightness).

Since the default "out of the IBM box" LCD brightness setting is "high/7" when operating on AC power and "medium/3" when operating on the battery, the trick here is to set up your ThinkPad so that it does not operate on those default settings, but instead defaults to the low/zero LCD brightness setting when booting up—because, if you're using IBM's defaults, your computer, if operating on AC power, will always boot up to level 7 LCD brightness and blink off immediately before you're able to reduce the LCD brightness level to zero. Thus, you're never going to actually be able to figure out the triggering cause, from which the solution can be determined. Here's how to set up your ThinkPad so you can test whether the LCD brightness setting is the trigger causing your LCD panel to go blank. If it is, then swapping out the LCD panel—and nothing else—is the solution.

Set LCD brightness to default to low/zero setting

ThinkPad's Battery MaxiMiser Wizard allows you to create custom "Power Schemes". When creating a custom Power Scheme, you are able to set the LCD brightness level of that Power Scheme to low/zero. (Recognize that every Power Scheme has two halves: one when you're operating on battery power and the other when you're operating on AC power.) You can also modify any previously existing custom Power Scheme by right clicking over the custom power scheme's name and then selecting "Modify".

If you set up your computer to use and default to a "Battery MaxiMiser created" Power Scheme with a low/zero LCD brightness setting, and if you shut down your ThinkPad when it is set at low/zero LCD brightness (because, until Battery MaxiMiser loads, initial boot up is based upon the LCD brightness setting when the computer was shut down), there's more of a chance that your screen will actually come ON at boot up. You will then be able to manually play around with the LCD brightness settings by pressing Fn+Home (to increase brightness) or Fn+End (to reduce brightness) and see what happens. If that's the trigger, then replacing the LCD panel is the solution. [Whether it's the LCD panel itself (as a whole) or merely the backlight bulb, I don't know. But I do know that it's way easier to replace the entire LCD panel as a whole than it is to try to replace just the backlight bulb. Being able to buy a (claimed to be new) replacement LCD panel on eBay for $89 + shipping, I just didn't figure that I wanted to go through the hassle of trying to replace just the backlight bulb.]

[Before replacing the LCD panel, I had tried replacing the inverter card for the reason that comments on the Internet indicated this to be the most likely solution to the problem. However, even after replacing the inverter card, the blank screen problem remained. The problem was only solved with the replacement of the LCD panel.]

[Note that using the ThinkPad Presentation Director program to switch between display settings (Fn+F7), which you might wind up doing if using an external monitor, may interfere with your plan to set and keep the LCD brightness setting on low/zero. All Presentation Director "Display Schemes" (except "My Normal Display Settings") have an option which, if checked, cause the use of the "Presentation (with projector)" "IBM out-of-the-box" power scheme, which sets LCD brightness at medium/3 if using battery power and high/7 if using AC power. The LCD brightness setting of the "Presentation (with projector)" power scheme cannot be modified.]

Procedure for Replacing a ThinkPad LCD Panel

The starting point is to obtain a copy of IBM's Hardware Maintenance Manual for your particular ThinkPad model. Download this from:

http://www-307.ibm.com/pc/support/site.wss/homeLenovo.do?country=us (Note: Clicking the link will open into a new browser window. To return to this website, simply close or minimize that window.)
  1. Fill in your "product number" (i.e., the 7-digit machine "Type"+"Model")
  2. Click "Go"
  3. Click "User's guides and manuals"
  4. Click "Hardware Maintenance Manual" to be taken to the download page for your particular ThinkPad laptop's Hardware Maintenance Manual.

The Hardware Maintenance Manual pretty much covers most of what you need to know to swap out a ThinkPad LCD panel. The diagrams appear to be sufficient explanation. But, the following is some extra explanation that I learned along the way that was NOT INCLUDED IN THE MANUAL for my ThinkPad T42:

1 — Despite what the Manual says, you do NOT have to take apart anything in the lower keyboard section of the notebook—which reduces the scope of this task SIGNIFICANTLY!!! Following the steps in the Manual, you only have to first remove (a) the LCD front bezel and (b) the inverter card. The steps to disassemble the LCD panel from the back/top cover and the various other "all attached together" stuff surrounding the LCD panel are adequately explained. But you don't even have to take apart all of the items illustrated. You just need to get to the point where you can remove the LCD panel from the hinges (extended) by removing 4 screws that secure the LCD panel to the hinges. You then just re-attach the new LCD panel with those 4 screws and put it all back together. It's going to take you a bit of time carefully doing the detail work, but it's all pretty straightforward.

2 — What the Manual calls "Screw caps" are, in reality, simply plastic coated sticky tabs. You can remove them with a sharp pointed object. If you're careful, you won't damage them too much.

3 — The LCD front bezel is adhered to the LCD panel at several locations with double-sided sticky tape. Inserting a small flat-bladed screw driver between the bezel and the frame of the LCD panel and slowly and carefully twisting the screw driver causes the adhesive to come loose and the two pieces to separate.

4 — Both the Bluetooth antenna and the LCD cable assembly are secured to the LCD panel with tape. This may sound obvious, but remove the tape only as to the portion of the tape stuck to the LCD panel. Since you're going to be re-using the other items, there's no need to disturb the portion of the tape stuck to them.

5 — For the T42 at least, one does not need either the ThinkPad CE Utility Diskette or the ThinkPad Hardware Maintenance Diskette to complete this process. Older model ThinkPads may need the CE Utility Diskette. For more on this issue, see: CE Utility Diskette / Hardware Maintenance Diskette

6 — The Hardware Maintenance Manual for my ThinkPad T42 listed 3 (equally interchangeable) replacement 14.1" XGA LCD panels (manufacturer/FRU part number):

Samsung - 11P8352
LG - 92P6726
CMO - 92P6675

Calling IBM/Lenovo parts (1-800-388-7080), I was told that IBM/Lenovo's price on each of these, as new replacement parts, was: Samsung, $335.00; LG, $471.00; and CMO, $482.61. What this indicates to me is that the Samsung is a cheaper product. Lo and behold, when I opened up my "blank LCD screen ThinkPad", I found that my ThinkPad had the Samsung LCD panel installed. When I bought the replacement LCD panel, I made sure NOT to buy another Samsung panel.

If I'd have known all this in the beginning, and how relatively easy this was, I'd have done this months ago.

— Rich Lang
    September 2009