Trying to Resurrect T20: LCD Display Problem -

[PeteS457]

Hi All:

I bought a T20 back in 2000 and after about 3 yers, the display starting having problems. I pretty much just stashed it and bought a T42p since I wanted an upgrade anyway. However, I've just moved into a new place and would like to resurrect the T20 as a backup laptop. (Previously upgraded to 512 MB RAM so it will be OK for basic ops.)

The display when it started going bad would have bands of red/pink throughout the display. Then a few weeks later, the display would be black/dimmed to where you could just see the Windows desktop. After a few minutes, it would lighten up, but the discoloration (red/pink Matrix-type streams and bands) just got worse. After retiring it for three years, I've resurrected it and attached it to a external monitor. The display on the external monitor is perfect. However, the LCD is totally blacked/dimmed; it never lightens up to the discolored display I used to get.

From reading the forums, it appears that it's a given that the backlight (CCFL?) is bad. Here are my questions:

1. Best place to buy - eBay? Is there a place I can get the FRU number to ensure that I buy the right backlight? I've seen reports of it being $10-20.

2. Has anyone else run into exactly the same scenario? Is it possible (hopefully) that this is all it is?

3. Does the fact that the computer displays perfectly on the external monitor rule out the inverter? I guess it's possible the ribbon/cable could still be bad in addition to the backlight. Does it sound as though the display may still be good though since I can see dimly the Windows desktop?

4. I'm not a solder guy, but I guess I'll learn. From reading here, I have to know how to do that, right?

Thanks a lot for your help. I tear apart desktops all the time, but that's easy. I have taken this laptop apart once, but this is a pretty daunting exercise for me and I want to make sure and do it correctly. Plus it's a chance to learn. The laptop isn't worth much otherwise.

[awdark]

Its probably easiest to change the cold cathodes as they are the most likely to burn out.

Ebay does seem like the best place to get all this stuff, I got my motherboard from ebay...

It does sound like your ccfl is burning out instead of an invertor problem. I think I recall reading a bad invertor will either flash or have no light in contrast to a burning out ccfl where the death is more like a fluorescent bulb.
When you say pink and all those colorful colors, its the backlight right? Like if you display white on the screen, the back looks pink when it should be white right? If yes then backlight. If its like lines on the LCD (uneven) then its probably the ribbon or lcd.

The fact that it can display on an external monitor doesn't rule out the invertor. The invertor circuit simply converts the power from the laptop, (lets assume 12v) and converts it to 600volts.

I haven't dismantled the Thinkpad LCD before, so I am unsure about how its all held together. But, I can tell you the bezel is held in place with a ton of little screws and you have to kinda pop it off from the bottom up.
The LCD appears to be held together by clips so you will most likely have to stab a screwdriver or knife to pop the clips open. Also, be weary of ribbon cables. I recently replaced the backlight of an old LCD (desktop one not a laptop one) and after popping the front frame of the LCD off, I tried to lift the LCD and realized it was still held down by ribbon cables. Had to flip it around and detach the controller board and unhook the back cover of the lcd to get to the light box and ccfls.
Also noteworthy is don't touch the surfaces of those plastic sheets within the LCD. They said that if you touch it, that fingerprint would be almost impossible to clean off and we don't want weird shadows now do we?

blah blah blah...

Look up lcd repair on google or lcd backlight and check those guides out. I think lcds are all built similar so it owuld be useful.

You will need to solder the wires to the end of the CCFL and they do say don't overheat it or it will pop on you. So use one of those heatsink clips, loop the wire (so end up with 2 loops), and solder it together quickly. Heat solder onto tip of iron, touch to the loop with more solder on the bottom. Should solder together nicely.

[JohnnyM]

I once attempted replacing the CCFL with less than stellar results. I found the soldering job was very delicate and precise. The power going to the bulb needs to stable, and a bad solder job (like mine) will act like a resistor. When it was finally put back together, the bulb mostly worked but there was no display. I ended up getting a new screen from ebay for about $60.

[vlyne]

It's probably a bit late now for the OP but I would expect a bad CCFL to give a graded or uniform tint - a more "analog" problem than a "Matrix-type" problem. The latter suggests LCD cable or connector problem, or LCD itself.
Cheers