T41 power is on but screen off just after OS started!

[lht2ht]

Hi,

My T41 is with me since 2004 and I love it.
Below is the sad story.

History
Recently, its fan was very noisy and slow that could not release heat from T41 and make my laptop intermittently stop running due to overheat. I changed new part (same part ID) bought from eBay. Same time, I also bought a 9cells battery. After changing all, fan worked for a couple of times and stopped. Of course my T41 did not worked as well.

With some search around the internet, I found the problem was F4 fuse (I even found a pdf diagrams of T41's mainboard, don't remember the website because I saved it for my own reference and forgot to save the link). Change the F4 fuse (I DIYed). The fan (new set) worked but then there was new issue: my T41 cannot keep running for long.

Here is what happened: I started the computer: OK. Fan: OK. Leds: OK. CMOS checked: OK. (If I want to set and update/change CMOS parameter, press IBM button for setting up: OK. Have to Save and Quit CMOS configuration after doing that, of course).
OS start: OK. (I tried with original Windows XP and Sun Solaris 10, installed separetely on two different HDDs. I did swap them when I wanted to use this or that OS)
OS checked system and proceeded to open the first screen: not OK. Right after finishing checking system, the screen went blank and I could not do anything else except press and hold Power button to shutdown the computer. Power led (green): OK.

Solution tried:
- Thought it was power problem, I tried with just battery, just main power and battery/main power combine. Same problem. <br>
- Press and hold power button tricks someone suggested in this forum does not help as well. I even took off CMOS battery to reset CMOS setting and repeat the same process: same thing happened everytime I started T41.
Even worst, after first or second time the OS could come out, the computer just started with power led ON and fan ON, but nothing displays. Press-hold trick and CMOS battery may bring the situation back that may display CMOS checking but OS still cannot go far.

I indead searched for this issue in the forum (tediously browsing almost 100 pages in ThinkPad T4x Series topics) and found someone had the same problem (seems so) with his child's T41 but all I have is a reply that refer to something called "sticky" and southbridge which I am not familiar with. The reply also suggested the last solution is to replace the mainboard.

I would like to ask if anyone else here have got the same issue can share experience.
I'm appreciated any reply.

Thanks and Regards,
HT

[Harryc]

Well, Southbridge bonding is easy to check. Put some pressure on it with a thumb while powering on the laptop. You can do this in a dock with the keyboard removed, or with the keyboard physically removed but still hooked up via it's ribbon cable. You'll have to remove the palm rest and the keyboard bezel as well to see it.
http://forum.thinkpads.com/viewtopic.php?f=2&t=89216

[poshgeordie]

Welcome to the forums and sorry to hear of the problems you're having.

This is a very common problem with these laptops and could be either an unsoldered Graphics (GPU) or Southbridge (SB) chip.

One way to find out which chip is unsoldered is to start up the laptop and when the screen's blank, and to switch it off by pressing the On Off button.

If it takes around 5 secs for it to switch it off then it's 95% an unsoldered GPU.

If the laptop switches off immediately it's often an unsoldered SB but could be the GPU.

These chips have hundreds of tiny solder balls which solder the chip to the motherboard and what's happening is that some have become unsoldered.

The faulty chip can be repaired by infrared reflowing, that is the chip is heated up using specialist Infrared Reflowing equipment which melts the solder balls and resoldering the chip back onto the motherboard.

Even better is to replace the solder balls with new ones by Infrared reballing. This refurbishes the chip and so should continue to work for a long time.

I do not know of a company in your area which does this; there may be companies locally or in Malaysia. I offer the service in UK and Europe but it would be too expensive for you to send your board to us.

There are DIY methods such as using a heat gun to resolder the chips but this is a very dangerous process which may well permanently damage the chips and motherboard: forum.thinkpads.com=2&t=57021.
Also if it does work it often fails again within a short period of time.

[Mike Blake]

Out of curiosity, do you see a screen if you hook it up to an external monitor?

[poshgeordie]

Out of curiosity, do you see a screen if you hook it up to an external monitor?

Good point Mike, but bear in mind that there are two video outputs - digital to the internal screen, and analogue to the external RGB connector - and as you're saying occasionally it's possible to have video via RGB with no internal, but it's no indicator that the GPU chip is 100% OK.

@lht2ht Go to my sig and download the Links doc and then the Fuses doc.

[Mike Blake]

Nick, I was offering the suggestion more in the spirit of giving him a possible alternative to spending time and money on the problem. Like when you tell the doctor it hurts when you do this, and he says "Well, don't do that!"

[poshgeordie]

Nick, I was offering the suggestion more in the spirit of giving him a possible alternative to spending time and money on the problem. Like when you tell the doctor it hurts when you do this, and he says "Well, don't do that!"

Good point and well made Mike. Fingers crossed it works from that port.

I get a bit blinkered sometimes with this problem and need the likes of you to give others the full picture.

[GomJabbar]

If I understand your symptoms correctly, this could be a display backlight issue. Just had to send in my T42 (to Moniserv) to get my failed backlight replaced (with similar symptoms). This is my 3rd failed backlight with my T42's (3 total T42's in the family).

It is a bit difficult to see, but try shining a light onto the display and see if you see any text or images at all. If you can, then it is probably your backlight (or possibly inverter) that has failed.

[lht2ht]

Thanks Harry, Nick and Mike,

1. I connected to an external monitor when the laptop's screen was blank. The external monitor was also blank.
2. I found the soundbridge chip. It's Intel 82801DBM right under the wireless card. Slightly pressed on it when turning the laptop on as Nick suggested but the laptop could not start normally.
3. Turn the power switch off, the laptop power light went off immediately (less than 1sec). Then it very high possibility that the symptom is caused by SB's faulty. Is it right, Nick?
Then the problem is by SB, not GPU.
Why I can say that. Because during this test, I could turn the laptop on once, screen is OK, CMOS test passed. When it came to Solaris boot menu, I did not touch anything. Just let it counted down from 30 seconds before booting to Solaris using default option. If GPU got anyproblem, I could not see anything on the screen, am I right?
However, right after the Solaris graphic screen came out, the laptop suddenly blacked out. Screen was off, HDD off, fan off, no light. I used external power, no battery.

After that, everytime I tried to switch it on, I could see wireless LED , HDD and CAPLOCK LED also on for a while when hardware check was proceeded. Then there was only power light (Z light) on and fan was working. Press ON/OFF button, the laptop turned off very quickly (~1sec).

Nick, from your reference about reflowing (http://forum.thinkpads.com/viewtopic.php?f=2&t=73945), there are two things happened to my T41:
"
* Screen is blank from switch on, but everything else appears to work (GPU)
* 2.0 USB port only works at slower 1.1 speed (SB). "
In fact, I did not know if it was 2.0 - 1.1 problem or not. I just do remember that my T41' USBs did not work properly before. It could be used for mouse or external keyboard or memory with external power source (e.g. from camera). But it had not been detected external HDD for at least 1 year time. For USB thumb drive: sometime on, sometime off.

Then what is the problem here?
Sorry for late reply as I was quite busy lab work these days.

Regards,
HT

[lht2ht]

If I understand your symptoms correctly, this could be a display backlight issue. Just had to send in my T42 (to Moniserv) to get my failed backlight replaced (with similar symptoms). This is my 3rd failed backlight with my T42's (3 total T42's in the family).

It is a bit difficult to see, but try shining a light onto the display and see if you see any text or images at all. If you can, then it is probably your backlight (or possibly inverter) that has failed.

No, I don't think it's backlight issue, GomJabbar. Because the screen can display properly at least once while booting.