T43p black screen after experimental noisy fan improvement

[thinktwice]

Hi,

After I improved the fan of my Thinkpad T43p, I have some blank screen problem; more exactly, the screen remains black and the splash screen does not display at all.

At the bottom of the screen the diodes light up green when I power on the laptop.
During approximatively one second, the "battery diode" is bicolor green/orange and then light up green. I assume this illustrates how much loaded the battery is.

The fan works wonderfully, silently and without excess. However, it does not start at maximal speed like previously.

I cannot say if the hard drive is rotating or not. Probably not, because I cannot hear it and the hard drive diode doesn't lighten. All the system was working perfectly before (excepted the noisy fan and a sometimes frozen touchpad).

I tried removing-reinstalling the battery and the same with the button battery for the CMOS (10 minutes). The hard drive socket appears correctly plugged.

Switching the hard drive with thus of another T4x does not give more results.

Both RAM cards appears correctly plugged and I unpluged/repluged them to be sure.
Between the ATI Graphical Processing Unit (GPU) and the copper heat sink is the original black thermal paste from Lenovo.

To detach the heat sink from the GPU, I used dental floss impregnated from methyl-ethyl-cetone (since I had no isopropanol) and applied a shear movement between the bottom of the thermal paste and the ATI chip.

Below the black thermal paste is some pink fabric that I was not aware of.
During shearing, this tissue was detached from the GPU and stayed well pasted to the thermal paste. Was just a little damaged in one corner.

There is also a second smaller chip below the heat sink. I was not aware about it.
A very thin thermal paste detached from it. I cannot see any apparent damage to that chip.

So, both chips look nice, but I cannot exclude some electrostatic damage, especially concerning the use of the dental floss.

The ends of the fan blades were scrapping the aluminium cage at the bottom of the fan. After disassembling the fan cage, I pushed at its center (bottom) to lift the rotor. As the fan cage is very narrow, making then the fan blades scrapping the upper copper plate, I had to rise a little the copper plate. For this, I used the rods from coton swabs, that I splitted lengthwise using a cutter, and clipped on the upper borders of the aluminium chassis.

The slightly raised heat sink (~0.5 mm at the fan side) was put again in the laptop.

No new thermal paste was applied, but I cannot see any gap between the ATI chip and the heat sink's pink fabric. All seems OK from a mechanical point of view.

The small button that transmits the "open/close" status of the screen (near the left hinge) seems working.

The small electrical switch that it actuates also seem OK from a mechanical point of view.
(Not tested electrically.)

I can see nothing more if I connect the laptop to some external monitor.
Also tried pressing Fn+F7.

The small metal tab on the left of the radiator that provides the contact with the motherboard is correctly fixed with the screw.

Things were done with care. I may not have been careful enough with the static electricity.
However, I avoided touching electronic parts.

Thank you for any clue that would help me diagnose the problem.

[RealBlackStuff]

There is also a second smaller chip below the heat sink. I was not aware about it.
A very thin thermal paste detached from it. I cannot see any apparent damage to that chip.

Go back in and take the fan out again.
You need to clean up the second smaller chip as well as the matching counterpart on the bottom of the fan.
That chip is the all-important CPU, which needs even more and better cooling than the GPU.
Buy some Arctic Silver 5 and apply that, before you put it back together.
There are tons of posts on how to apply AS5.

(Think three times next!)

[thinktwice]

Thank you for answering so quickly. I was aware about Artic Silver 5, as well as a competitor product mentioned by AdaSch somewhere on the forum.

Sure that I'm interested in getting some quality thermal compound.
However, as I can imagine such compound not being cheap I first would like --if possible-- to diagnose which component is causing the failure and know if one chip (CPU or GPU) or the whole motherboard has to be replaced.

Is there no way to diagnose the failure before purchasing thermal paste?
Is there real risk of overheating if powering on the laptop just a few seconds?

> Think three times next!
Sure. My pseudo already come from what I should have done...

[RealBlackStuff]

A 3.5g tube of AS5 costs about CHF 15.- on eBay: http://www.ebay.ch/itm/Arctic-Silver-5- ... 27c6230305
1 Tube is enough for at least 4-5 applications.
You probably spend that much for your daily trip to the pub, so tomorrow buy AS5 instead!
It takes only seconds for the CPU to overheat, don't try to save on the wrong side...
And take those silly "cotton swab rods" out, they prohibit proper contact between CPU and fan.
You probably wrecked your fan or its cage by pushing too hard on the wrong spot...

[thinktwice]

I agree, AS 5 is quite cheap on eBay. I imagined it much more expensive.

The "silly cotton swab rods" are not as silly as you may think.
I was forced to open the cage for several reasons:
- First, the fan ends were scraping the bottom of the aluminium cage.
- Secondly, drilling a 2,2mm hole at the bottom of the cage would have had the contrary effect of what was my Thinkpad needed. (http://forum.thinkpads.com/viewtopic.php?t=69539)
- Thirdly, I needed to understand how the fan was built.

Because the border of the aluminium cage is very thin on one side, it was practically very difficult to increase the cage height 0,5 mm. The rods were the only longlasting solution that I found. Soldering aluminium and copper is impossible unless you have some special compound.

The "cotton swab rods" solution allowed me to suppress the resonance cage between the fan and the bottom metallic plate, because the rotating axis is no more directly in contact with the bottom of the Thinkpad. The fan noise is very low now.

[ajkula66]

The "cotton swab rods" solution allowed me to suppress the resonance cage between the fan and the bottom metallic plate, because the rotating axis is no more directly in contact with the bottom of the Thinkpad. The fan noise is very low now.

But now you have a T43p that won't boot...

[Tasurinchi]

I used to use AS5 since I started assembling my own desktops. But after reading very positive reviews in other forums I started using Artic MX-2 cooling paste with excellent results. You can get if for 9 CHF from here: http://www.digitec.ch

[thinktwice]

Yes, Arctic Cooling MX-2 seems nice and MX-4 even more.

Strangely, at Prodimex, MX-4 (4,80 CHF) is cheaper than MX-2 (8 CHF) for the same quantity (4g): http://www.prodimex.ch/pSearch.aspx?SEARCH=Arctic+MX

Cannot understand why. Maybe is MX-4 less known than MX-2.
On Arctic Cooling's website (http://www.arctic.ac) it's the contrary; MX-4 is more expensive than MX-2.

I would not be surprised if Arctic Cooling thermal compounds were based on diamond powder, as Arctics Cooling tells about "carbon microparticles" ...
Diamond is nothing else than pure carbon. Diamond is an electrical insulator, but an excellent thermal conductor. This is of course pure speculation.
It could be interesting watching at the paste with a microscope.

There is also ICY Diamond Thermal Compound http://innovationcooling.com/overview.htm , which is clearly based on diamond particles. I suspect that this product could be hard to apply because high diamond could mean high viscosity. Feedbacks welcome.

Back to my question...
How could I diagnose if the CPU or the GPU was destroyed ? I cannot see anything on screen...

[ajkula66]

Once you've re-inserted the CPU and secured it properly, remove all the RAM and power the machine on.

Does it beep?

[thinktwice]

Thank you ajkula66 . Could you explain what you mean by reinserting the CPU?
Do you mean unscrewing the card on which the CPU is, repluging it and screwing again?

I applied some thermal compound on the CPU and GPU.

I did all what you describe (excepted that I did not reinserted anything). Of course, the screws on the back of the laptop were screwed again.
The laptop doesn't beep.

When I open the casing, I can see a grey thin plastic tab near the power-on button.
I cannot remember where this tab should be. I pressed the tab down against a shiny black plastic surface.

When I watch the laptop from its rear face, with the screen closed, I observe that the border of the screen is not perfectly parallel to to the casing below it. There is a curvature. The maximal tension appears located near the hinge on the side of the power supply, like if some screw was too long not far from this location. However, I have carefully checked that the screws have the right length. Of course, the fan was rehaussed about 0.5mm, but I don't think that this should lead to such a curvature.

[ajkula66]

Yes, unscrew the CPU, check for any bent pins, re-insert and tighten.

If the board still doesn't beep with no RAM installed, start looking for a new one...

[thinktwice]

After following your advices, I have good reasons to think that the CPU is dead.

However, it should be possible to just replace the CPU (which has a FRU) and not the whole laptop. Such a CPU costs around 50 USD on auctions sites.

[ajkula66]

Just buy the cheapest applicable (PM740) CPU which is $10 or less and make sure that the machine boots...and then we'll take it from there.