Fixing a bad backlight on an IBM ThinkPad R32

Recently I bought an old ThinkPad R32 on Tradera, the Swedish equivalent of EBay. The plan is to use this laptop as the basis of a DIY tablet-PC project.

Anyway, I got the laptop cheap because the LCD panel was broken. The LCD displayed an image but it was very dark, a classic backlight problem. After a bit of googling around I found out that either the CCFL (Cold cathode fluorescent lamp) or the LCD inverter could be the cause of the problem. The CCFL is basically a lamp which illuminates the LCD pixels from the backside while the inverter is a circuit board which supplies the CCFL with the correct voltage.

Replacing a CCFL seems very complicated while replacing the LCD inverter is trivial, at least on this particular ThinkPad model. According to Google the most common cause of backlight problems is the inverter. To confirm that this was the case I ripped the LCD panel out of my old ThinkPad A20m and connected it to the inverter in the R32. I figured that if the R32’s CCFL was broken the A20m’s LCD panel would light up when I plugged it in. It didn’t light up but I did see the same very dark Thinkpad logo during the BIOS initalization so I concluded that the inverter was the problem. After a quick search on EBay I found a new inverter for $30 including shipping to Sweden.

The disassembled ThinkPad A20m (left) and R32 (right)
The new inverter has been installed
The inverter is located below the panel
The new inverter
The new inverter

When the inverter arrived after about a week I followed the instructions over at Laptop Repair to replace the old one. Unfortunately, nothing happened when I turned on the laptop. What Laptop Repair fails to mention is that, at least with ThinkPads, you may have to run a program which updates an EEPROM chip on the inverter after it has been connected. This EEPROM stores the id (manufacturer and size) of the panel connected to it. If the wrong id is set or no id is set at all the panel will stay black.

It took me a while to find this information in the ThinkPad R32 Series Hardware Maintenance Manual:

System board/LCD/Inverter replacement notice
Restoring the LCD panel ID
The EEPROM on the inverter stores its supported LCD type ID code. If you replace a LCD with one of a different brand or use a new inverter, the ID information in the inverter EEPROM should be updated.
Follow the steps blew to set the LCD panel ID:
1. Install the ThinkPad Maintenance Diskette and restart
the computer.
2. When the IBM logo is displayed, press the ′′ESC′′ key
few times until BIOS copyright and diagnostics screen
appears.
3. Select 1. LCD Panel ID Utility from the main menu.
4. Follow the instruction on screen to read current or to
set new LCD Panel ID code.
5. Restart computer : the new LCD should work normally.

I quickly found the ThinkPad Maintenance Diskette. Then I spent hours and hours trying to get it to boot from a USB memory stick. According to the forums I’ve read this disk MUST be booted from a floppy drive (it can be a USB floppy drive). The forum posts say that making a bootable CD out of it will not let you write to the EEPROM. Since I don’t have a USB floppy drive at my disposal I tried for days to get the floppy image onto a memory stick and fool the ThinkPad into believing that the memory stick was a floppy disk. It’s supposed to be possible. I finally gave up and bought a USB floppy drive on Tradera.

Now I was finally able to boot the damn disk using the floppy drive but it didn’t seem to be the right disk. No such thing as “1. LCD Panel ID Utility” turned up in the menu. After a bit of more googling I discovered that the maintenance manual was incorrect. I should have used the so called ThinkPad CE Utility Diskette instead. Thank you IBM!

After a couple of hours I managed to find the correct version of the CE Utility Diskette for the R32 ThinkPad model (this link was of great help). First I ran the LCD Panel Utility with the old inverter in place to get the correct LCD Panel ID. Then I replaced the inverter and ran the utility again to set the correct LCD Panel ID. And now, finally, the backlight works great!

First boot up after the panel ID has been set
First boot up after the panel ID has been set

14 thoughts on “Fixing a bad backlight on an IBM ThinkPad R32”

  1. Hi, I replaced the inverter board but the screen is still dark, and haven’t been able to find the CE Utility Diskette for the T20 – do you know where I can get it? I tried using yours but it freezes. Also the links on the IBM ftp site from paul.sladen.org do not work as the pub directory no longer contains those directories. If I cannot set the panel ID I have no way to know if that is problem or it’s the backlight, so I would get stuck.
    If you could provide some info on finding the CE Utility Diskette for the T20 I would appreciate it.
    Thanks

  2. Hi! I guess I should have mentioned that you need to change the FTP server name to http://ftp.software.ibm.com and use /pc/ instead of /pub/. E.g.: ftp.pc.ibm.com/pub/pccbbs/mobiles/ceutil1m.txt becomes ftp.software.ibm.com/pc/pccbbs/mobiles/ceutil1m.txt

    Anyway, I just found a text file on the IBM FTP server which gives you a short description for the files in the /mobiles directory: ftp://ftp.software.ibm.com/pc/pccbbs/mobiles/00index.txt

    Also, this file has descriptions for some files in other directories on the IBM FTP server. Though it doesn’t seem to include all files in the /mobiles dir.

    I cannot find any information about a CE Utility Diskette for the T20. The Hardware Maintenance Manual for the T20 doesn’t seem to mention that you need to do run anything after replacing the inverter.

    If your display isn’t completely black but still shows a faint picture (e.g. the ThinkPad logo when it boots up) I would say that the inverter isn’t the problem but rather the CCFL.

  3. Niklas, My Kudos to you.
    This is one of the best described “How To ???” I have ever seen. It is Informative, Descriptive, Visual and full of info on how to get the necessery tools for the job at hand.
    I was just googling and came across your blog.
    Great job Niklas

  4. thank you so much for this blog! i agree with silverfox that it is among the more informative and well written i have read. however, i am a bit confused. in the blog you mention that your screen was not completely dark, and you could see the thinkpad logo when it booted up. then you mention that replacing the inverter nad updating the eeprom chip fixed the problem. but on your may 13th response to the first comment you say: If your display isn’t completely black but still shows a faint picture (e.g. the ThinkPad logo when it boots up) I would say that the inverter isn’t the problem but rather the CCFL.

  5. Thank you for those kind words!

    The may 13th comment was a response to the may 12 comment made by Anonymous. He or she had already replaced the inverter but the LCD was still dark. In my response I said that if the display is still dark after replacing the inverter but it isn’t completely black I would say that the CCFL is the problem and not the inverter.

    Hope that makes things clearer.

  6. thanks for the quick response. would you happen to know anything about how to update the eeprom id in a dell laptop?

  7. Hi.Read your great guide on changing the backlight on the R32 Thinkpad. I have just cxhanged the display screen for a friend but i am having difficulty obtaining the ce utility diskette as the links are either dead or with IBM you need to be a partner or authorised user to be able to access the file.
    would be very grateful if you couldhelp me obtain the CEUTIL1M.EXE file.
    Thanks in advance.
    joe

  8. Hi!
    Good guide… I’m in the same trouble with one of those machines: Where to obtain the blessed diskette? If you can help me i’ll be very very grateful to you.
    Happy new year from Chile!!
    Alexis

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