T42 issue : screen suddenly black but display OK if reboot.

[thinktwice]

Hi,

I'm facing a strange issue with my T42 (Type 2373-6ZG).

After a few minutes the screen becomes suddently black and key-in "Fn+F7" or any other key does not make the backlight come back. (It was previously working.)

I have no other choice than pressing the "Power on/off" button a few seconds to shut down the computer and restart it.

My first hypothesis was GPU bad contact, but strangely the display comes back when I just start the laptop again without it was moved at all.

Sometimes, the problem occurs just a few minutes after Windows was started.
Sometimes, it only occurs after about one hour.

Any idea ?

[smashkenazi]

Try removing the wireless card under the trackpad. It worked for me.
I wasn't using the wireless card, so I've left it like this.

[thinktwice]

Thank you.
Yes, meanwhile I did it as I observed the card was quite large and was swingging a little.
Maybe at its outermost side, it could touch the motherboard if the touchpad or some keys were hitted with some energy.

The problem remained, although maybe less frequent than before. Of course, I insulated the main/aux cables from the wireless card the best I could. What I observed it that there's very few space between the touchpad and the motherboard. Maybe the cables are still creating some bad contact from time to time.

The issue always seems occuring when I press the touchpad or a key.

I also disabled the active hard drive protection, as it is based on accelerations and vibrations could potentially switch off the hard drive. However, even if the hard drive is switched off, the screen should remain bright.

[Ken Edmonds]

I had exactly the same problem a month or so ago. More accurately, I've still got it.

The consensus was it's the usual GPU problem but it puzzles me too that it always starts up fine, even seconds later. That's what makes me wonder if it's the right diagnosis.

It had never even twitched in the 10 months or so I'd had it, then suddenly went black and has never worked for more than a few minutes since.

Taking the wireless card out isn't an option for me, using it anywhere in the house is my sole justification for having a laptop.

[sethstorm]

Hi,

I'm facing a strange issue with my T42 (Type 2373-6ZG).

After a few minutes the screen becomes suddently black and key-in "Fn+F7" or any other key does not make the backlight come back. (It was previously working.)

I have no other choice than pressing the "Power on/off" button a few seconds to shut down the computer and restart it.

My first hypothesis was GPU bad contact, but strangely the display comes back when I just start the laptop again without it was moved at all.

Sometimes, the problem occurs just a few minutes after Windows was started.
Sometimes, it only occurs after about one hour.

Any idea ?

Most likely it is the GPU, especially that you mention how it is failing. The backlight on mine goes off first, then the whole system goes down with it.

[thinktwice]

I think the culprit is either the GPU or the touchpad.

I observed that there's less than 0,5 mm vertical space between the metallic strip that fixes the touchpad and the top of main/aux cables fixed on the the wireless card.

So, I unmounted the wireless card (although I need it). One issue was were to put the (antenna?) main/aux cables, so that they do not enter into contact with either the motherboard or the keyboard's bottom metallic plate. But I could find some solution.

Despite this, the "sudden black screen" issue remains.

There seem being high correlation with hitting the touchpad, but sometimes is no problem and sometimes the problem comes very quickly. So, it may be related to either some unstable electric status or desoldered GPU.

The very strange is that the machine always boots up correctly, even a few seconds after the problem occured.

[RealBlackStuff]

If you remove the keyboard bezel, you will see a micro switch on top of the LCD cable connector.
That might be dirty/faulty.
'Hammer' lightly on it a few times, then try again.

[Ken Edmonds]

That was one of my early thoughts when I had the same problem. I did try prodding it a few times but as the laptop didn't shut down or standby when the screen went black I discounted it fairly quickly. Equally, if I did shut the lid or hold on to the microswitch it didn't standby then either.

Like thinktwice, I'm puzzled why when rebooting it is always fine, without fail. Though I'm prepared to accept the opinion of people who know far more than I do, it just seems strange. My spares machine has got the classic fault and sure enough it's erratic.

[RealBlackStuff]

It's been mentioned before.
The most likely culprit is the GPU.
When it heats up, it loses connection through one or more of the ca. 650 solder balls between GPU and motherboard.
Reballing it would be the perfect solution, if you can find someone reliable...

If it were the Southbridge, you'd have problems with hard disk, CD, USB ports, printing, connections, to mention but a few.