X31 LCD screen corruption

[snv]

I could not find any problem reports in the forum archives with exactly the same symptoms, but I know that, in general, video problems on X31 are nothing new. Fortunately, the problem is not frequent so far.

The symptoms are:

The lower 2/3 of the LCD screen exhibit some flickering, and the picture gets blurred when, say, scrolling text or switching between windows. I would say, there is some ghosting in the lower 2/3 of the screen, where either some rows of pixels get delayed by a couple of seconds, or the delayed video signal gets somehow admixed to the picture (I need to look more carefully next time). The flickering and ghosting can range from barely noticeable to quite severe and impeading normal use of the laptop. The upper 1/3 of the screen is always fine.

The flickering and ghosting, once started, persist not only in graphics video mode under Linux (ati driver by xorg, version 6.7.197, xserver version 1.4), but also when rebooting to Windows XP or to the text-mode PC Doctor from the service partition.

The problem happened twice so far, first time about 3 weeks ago and the second time this week. It looks like the problem started after some moderately heavy use of the graphics (like scrolling text documents a lot), but I cannot be sure of it. Once started, it gradually gets worse, and then may become better or worse again - I have not noticed any pattern yet. It is not cured even by turning the laptop off, removing the battery for a minute, leaving the laptop off overnight. Both times the problem went away by itself after a day or two. Trying to press on or bend the laptop slightly at different places does not seem to help, but I did not try it without the extended life battery, which makes the laptop quite more rigid.

I use the computer almost daily, and use it a lot, but nothing too heavy on graphics: viewing PDF files and web browsing at most. When at work, the laptop is connected to an external CRT monitor, the laptop LCD turned off. No problems with the VGA output. Right now the temperature of (or around) GPU is 60C (as reported by `cat /proc/acpi/ibm/thermal`). I did not check it when the problem was showing up.

My ideas so far are (what I feel is more likely is listed first):
(1) the video chip getting unsoldered,
(2) some video cables not seated tightly or damaged,
(3) the video chip is overheating,
(4) electromagnetic interference of some sort inside the laptop body,
(5) the video driver corrupts the GPU in some way until it is reset somehow (is it possible at all?),
(6) other motherboard failure, video memory failure,
(7) the TFT martix is damaged.

I will look into the HMM and will try to open the laptop and see if everything is looking good, but am not sure if I have enough experience to identify the reason of the problem. Besides, it is my main working laptop, and I am afraid to break something if I experiment with it to much. If things will be getting worse, I'll probably end up getting another X31 or X32 and will be reparing this one in more relaxed circumstances.

Maybe someone will have any other ideas on what could be the source of the problem and what could I check?

[proaudioguy]

If the external monitor works fine the gpu is likely fine. I'd check the lcd cable, then the lcd.

[snv]

If the external monitor works fine the gpu is likely fine. I'd check the lcd cable, then the lcd.

VGA and LVDS are two distinct interfaces. Do they use the same pins on the GPU chip to deliver the signals? (I somehow doubt it, because the internal and external screens can work independently.) If not, then the external monitor working may not prove much, as just a few pins could get unsoldered initially.

[proaudioguy]

Well you asked a question, you got an answer and now you argue wiht the answer. It has been noted many times int he past that if the crap coming off the GPU is on both screens, then it's GPU related not the cable, not the inverter, and not the LCD. I suppose what you say could be possible as I do not have all the answers about how GPUs are soldered on the board. If you have all the answers then why ask the question? Had I been completely wrong I guarantee someone else would have piled on. This forum is very well self moderated.

[ajkula66]

Where I would begin is running PC-Doctor on every component of the system, especially video adapter.

If that doesn't show anything (I'm suspecting a GPU problem, although I'm not 100% certain at this point) I'd try running some VERY intensive video applications or games and look for the display going nuts.

If and when the display goes nuts, I'd hook up the external monitor and start all over again, looking for signs of corruption there...

Good luck.

[snv]

Well you asked a question, you got an answer and now you argue wiht the answer.

Oops - I certainly did not want to offend you and I appreciate your trying to help me... I am sorry if my reply sounded inconsiderate.

I did not mean arguing with your answer, I just wanted to understand the reasoning behind it. Your conclusion seemed somewhat illogical for me, so I replied in a hope that you or someone else might clarify it. I do not imply that you are wrong, I just do not know the details of the GPU physical interface to the motherboard, and the little that I know gives me some doubts that I can exclude it form suspicion.

I apologize for not wording my previous reply properly.

[ajkula66]

As stated on this forum many times before:

The output to LCD is digital while the VGA is analog and they're separate. It's perfectly possible to have VGA working on a machine with a defective GPU, I've had an X31 like that (along with many others that had exibited the very same behaviour) although the issue there wasn't the type of corruption that we're discussing here, but a different one.

Hope this helps.

[snv]

Where I would begin is running PC-Doctor on every component of the system, especially video adapter.

Thanks for your reply. I've done it before, and everything was fine. But the problem comes and goes, so I'll try running PC-Doctor again if and when the problem reappears.

If that doesn't show anything (I'm suspecting a GPU problem, although I'm not 100% certain at this point) I'd try running some VERY intensive video applications or games and look for the display going nuts.

That is probably a right thing to try. I would stress out the GPU and monitor its temperature at the same time. Now I'll have to think of some graphics intensive Linux applications - I do not even have decent games on the comuter

Does anybody know, if it is possible to unsolder the GPU by such a stress test? What temperature would be dangerous? (Do not want to kill my presumably-weak laptop by such testing.)

[ajkula66]

Given that your GPU is only 16MB, it won't take that much to stress it out, but it may be a while.

The machine will shut itself at 95 degrees C.

If your GPU is at fault, you'll need a new motherboard. Stress-testing won't make the things any worse than they really are...

Good luck.

[gongo2k1]

i've had this sort of erratic behavior before on a compaq laptop. it turns out that i had inadvertently loosened the display cable on the lcd just a little bit when i was installing wifi aerials in the case. it was frustrating because i must have re-seated the cable to the motherboard at least a handful of times before thinking about the OTHER end of the cable...

[proaudioguy]

I have had numerous computers with this problem and every time it's been on both the LCD and external monitor. I have no idea what the difference between digital and VGA is. I'm pretty sure all computers are digital so you lost me there. These machines were all A31s. I was told on this forum and also read many related threads that if the display issues appeared on the external display and the LCD then it was the GPU, this would make one assume the inverse was also true. As I said, I don't have all the answers, but it didn't seem like anyone was going to answer this one so took a shot. Still I think if the BGA came loose it would affect the image everywhere, not just the LCD. I should add that I have RDPd into these machines and the video artifacts then show up on the remote computer too. Pressure on the GPU or re-flowing solves the problem at least temporarily.

http://forum.thinkpads.com/viewtopic.ph ... 31+gpu+bga

http://forum.thinkpads.com/viewtopic.ph ... 31+gpu+bga

http://forum.thinkpads.com/viewtopic.ph ... 31+gpu+bga

http://forum.thinkpads.com/viewtopic.ph ... 31+gpu+bga

http://forum.thinkpads.com/viewtopic.ph ... 31+gpu+bga

http://forum.thinkpads.com/viewtopic.ph ... 31+gpu+bga

And this one which I monitored for the longest time......

http://forum.thinkpads.com/viewtopic.ph ... 31+gpu+bga

And there are many more.

[ajkula66]

GPU failures are like cancer...they have many faces, and usually quite a few stages...

Example #1:

I've owned an A31p (later sold to schen) that displayed all the symptoms of a loose GPU once booted into Windows, but would run Linux fine 8 times out of 10. Throughout all this time external display was perfect.

Slowly, but surely, the picture started getting corrupted in Linux, but was still good externally.

In the next stage, the corruption has spread to external display.

In the final stage, the machine lost video altogether.

Example # 2:

X31 that I've bought with the assumption of a bad backlight...machine would boot, but show a very faint image on LCD. Nothing wrong with external display.

After LCD was swapped with a known working one, along with a brand new cable and inverter, the machine still behaved exactly the same. New motherboard solved the problem.

I've owned several other machines that had behaved in a similar manner, and could possibly pull my notes out and get each and every one of them described, but I really don't feel like doing that.

Conclusion:

What I'm trying to say here is that in many cases you'll be able to see the failing GPU on the external display immediately, but in some you won't. You'll have to run it for a long time and/or stress the GPU in order to get the VGA output to show corruption.

I don't know how I lost you with the VGA...that output is analog, plain and simple, while the one going to internal LCD is digital. They have the same starting point ( GPU) but their transmission routes are different.

Hope this clears any misunderstandings and question marks that my previous post(s) may have left behind.

[snv]

A little update...

The X31 behaved well for 3 month, but the ghosting problem returned briefly two days ago and then again today (and it is still there). As I said, it is a kind of interlaced ghosting, where about every other pixel in the lower 2/3 of the screen gets delayed by a couple of seconds. The delay time itself seems to oscillate from almost zero to a few seconds in a pretty irregular way, every 5-10 seconds or so. Wierd!

I removed the extended life battery and tried to bend the laptop here and there, but nothing seems to change. I disassembled it couple of month ago, but everything looked normal inside. Will try to wait and see whether the problem will go away by itself, as it did the last two times...