T61 LCD display flickering with big patches of black and going to dark (very low light) afterwards

Question

I have a T61 which has Intel graphic card. It is seven years old and at times has a noisy fan.
Very recently it started to have problem with its LCD, it starts with slight flickering of light intensity from corners of screen, here and there, eventually covering the whole screen, goes away and comes back, happens for few seconds, the pattern repeats for few times, then big (screen-wide) patches of back starts to cover the lower 1/4th, one-half, 3/4th of screen, flickering between the screen content and black screen, till they cover the whole screen after 30-60 seconds. At that moment, the screen is very dark but with a close look, it is still possible (but very hard) to read it. Connecting it to external monitor (through its VGA), it is working very well. Showing same screen on both LCD and external monitor at the same time, the picture on external is solid, but picture on LCD can have this issue. At the moment of writing this message, the problem seems to not happening!! but it was happening during the past whole week including few minutes ago. I searched online and here in the forum and read few posts, and found about these issues:
- some T61's have Nvidia GPU and thermal effects over the time and stress on the package or solder balls can make loose connections (this is probably not my case since the interface to graphic card is by Intel)
- problem with LCD itself (it is working fine just right now)
- problem with graphic card (it is working very well over the VGA to external monitor)
- problem with the ribbon from mother-board to LCD (tilted the screen in different angles when the black patches and flickering are happening and didn't change the chaos much in any direction of making it better or worse)
- problem with bulb inside the screen (maybe the cause, but somehow decided for the last few minutes to working fine)
- problem with inverter (don't know yet what this part it)
- problem with some sort of mechanical part(s) being loose, gently tapped on sides and back of the screen while the phenomena was happening and again didn't have much effect on it in any direction.
I appreciate your time and good gesture of help, many of you would know more scientific/engineering ways of approaching the problem and how to root cause it. My sincere thanks beforehand.

Answer 1

>  the screen is very dark but with a close look, it is still possible (but very hard) to read it.
That sounds like a defective CCFL backlight or inverter.
>- problem with bulb inside the screen (maybe the cause, but somehow decided for the last few minutes to working fine)
A CCFL is essentially a high intensity fluorescent bulb. One failure mode is flickering.
>- problem with inverter (don't know yet what this part it)
The inverter is a power supply that converts the low voltage DC used in the rest of the ThinkPad to high voltage to drive the CCFL. I would expect that to fail catastrophically rather than cause flickering.
What to do?
CCFLs backlights are relatively inexpensive ($10 to $15 on eBay) but they can be difficult to replace because they're delicate. You may prefer to replace the entire LCD panel assembly or even the entire top cover assembly (which also includes the inverter card.)
The Hardware Maintenance Manual for the T61 provides detailed instructions for doing this sort of stuff if you'd like to see what's involved and decide what you feel comfortable doing.
Cheers... Dorian Hausman
X1C2, TPT2, T430s, SL500, X61s, T60p, A21p, 770, 760ED... 5160, 5150... S360/30