Help me find the cause of problem on a dead T42 (2373-A23)

[frankiepankie]

Hi guys (and girls?),

I have bought a T42 that has been dropped. It has no signs on the outside because of the drop.

I think / thought i could fix it.

The problem is: When i push the power button, the laptop starts, but there is no image displayed on the screen.

It does the normal startup things like:
The lights (caps lock, numlock, little moon) all blink once at startup
The laptop charges the battery fine
The DVD indicator is blinking a few times on boot
The fan is running (quite fast)

Measured the CMOS battery with a multimeter --> 2,94V (seems OK to me)
Also tried connecting an external monitor (VGA) and powering it on, but still no image (yes i pressed Fn + F7 a few times to be sure it would redirect the signal to the external monitor )
Also tried pushing on the cooling part above the GPU quite hard with my thumb, and then pressing the power button, also didn't work (i remember the loose GPU problem)
The ThinkLight won't turn on either, so i guess it won't even go as far as the BIOS

Is the motherboard broken because of the drop?
System board FRU: 39T5451

[Harryc]

Remove all of the RAM including the optional slot underneath and the slot under the Palm rest. Does it beep while booting up?

[frankiepankie]

No, it doesn't beep (removed both sticks)

Is that a good or a bad sign?

[ajkula66]

You can most likely kiss that board goodbye.

Try swapping the CPU if you have a spare, and check whether it beeps then, but this is a very long shot...

Good luck.

[frankiepankie]

OK

I have another T42 here, but i don't think the problem resides in the CPU.

Any other things i can try to fix it?

Or any advice on how to narrow down the problem (i am sure the mainboard is shot, but what part?)

I am quite handy with electronics (flashed my Xbox 360, flashed my PSP, jailbreak iPod / iPhone, soldered my own LED Bicycle light, etc etc ) so i am not scared by some soldering on the mainboard

[craigmontHunter]

The problem is not so much the soldering action as the type - the bga are difficult to resolder well without the right tools (I have tried with limited succes). Try reseating the cpu to make sure, then you need a replacement. I would get a r5x board with intel graphics to prevent the potential for the gpu issue.

Good luck

[frankiepankie]

I completely dissambled the T42 this evening, i have the mainboard connected trough a dock so i don't need all the hardware (Screen, wifi, keyboard, touchpad, battery etc.) connected.

I used a small pen-sized blowtorch to reflow the GPU chip, and the chipset chip (and some other BGA chips i saw on the mainboard).

The problem is, it still won't POST or have any video output (i have connected an external monitor to the dock).

I also connected the ThinkPad's internal speakers so i could hear beep codes, but nothing happens. (I am testing it without RAM, it should beep then, but it doesn't )

When i turn it on, the lights turn on, and the fan begins spinning, increasing in speed with steps, until it is running at full speed.

I think this mainboard is dead and never will wake up again
Already contacted someone that had an T42 motherboard lying around (only disappointment is that my current board has an 9600, and the replacement an 7500 )