T42 not powering up after assembling it back together

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redmond · #1 Post by **redmond** » Mon Oct 01, 2007 7:55 am

I have having heat issues with my laptop (T42p) and opened it up and applied some thermal paste to remedy the issue. I realize that while doing all this the battery was plugged in. In any case, now the laptop does not power up--in fact no lights go on after I plug in the power. It is pretty much dead.

I unplugged all the power supplies and have plugged in all the wires (fan assembly, keyboard, trackpad).

What could be the possible issues and how can I go about diagnosing the problem?

Thanks very much for your responses.

sktn77a · #2 Post by **sktn77a** » Mon Oct 01, 2007 12:45 pm

You sure you plugged the fan cable back in? (I forgot to do this when I switched my processor the first time

) Alternatively, you may have put too much thermal paste on which then acts as an insulator! Do you get any errors on bootup?

agarza · #3 Post by **agarza** » Mon Oct 01, 2007 2:33 pm

Maybe some thermal paste spilled onto the motherboard and caused damage. Unassembly everything, then disconnect the fan. Reconnect and see if there is thermal paste outside the edges where you put the grease.

redmond · #4 Post by **redmond** » Mon Oct 01, 2007 3:53 pm

cleaned it out entirely, but still no luck. it is completely dead.. when i plug in the AC adapted there is absolutely no response as if i never plugged it in the first place... also tried the batter which i know has charge that also doesn't work.

how can i tell if the mother board has shorted? i am scared i might be in for a huge bill if it is...

#5 Post by **richk** » Mon Oct 01, 2007 4:20 pm

If you worked on the machine with the battery in, you probably dropped a screw and shorted something. THe best you can hope for is a blown fuse, but unless you know a very competant repair place who also has a board he can get one from, you are looking at a new motherboard. Usually, if there is a blown fuse, there is other damage.

redmond · #6 Post by **redmond** » Mon Oct 01, 2007 4:25 pm

i wasn't aware there are fuses on the motherboard... where can i find the fuse and can i verify it myself?

#7 Post by **rkawakami** » Mon Oct 01, 2007 4:27 pm

If you plug in the AC adapter with the battery installed, does the charge LED turn on?

Some other things to try:

- verify that the AC adapter is functional. Check it with a voltmeter or use another IBM 16V 4.5A adapter. Same goes for the battery.
- remove and re-install the CPU. It might not be making proper contact in the socket. Do this with the AC and battery removed.
- remove ALL components that plug into the motherboard, except for the keyboard. This includes memory, hard drive, MiniPCI, Ultrabay, ethernet, etc. and see if you can power up. You should at least get the 1-3-3-1 beep error code (for bad/missing memory). If so, then re-install the memory and try powering up again. With the system off, add one piece of hardware back into the system and see if it still powers on.
- if you have a port replicator/docking station, attach the laptop and try using the power button on the port rep/dock

edit: "Fuses". There's more than one most likely, given what I've seen on other IBM motherboards. For your problem, you would have to check the one that protects the DC input jack AND the one that is connected to the main battery. Here's a picture of what one looks like on a T23 motherboard:

http://www.rkawakami.net/ibm_t2x/main_fuses.jpg

The big white block is the fuse that is in-line with the battery. There should be a similar one near where the DC input jack connects to the motherboard. Both can be tested by connecting an ohmmeter across the ends and reading 0 ohms.

redmond · #8 Post by **redmond** » Mon Oct 01, 2007 4:53 pm

thank you, that's very helpful! i will get my hands on an omhmeter tomorrow and run the diagnostic checks tomorrow. hopefully it's just a fuse.

will post back after i run the diagnostics.

redmond · #9 Post by **redmond** » Mon Oct 01, 2007 4:56 pm

forgot to mention, i unlpugged everything and tried powering up with just the keyboard plugging in which did not work.

#10 Post by **richk** » Mon Oct 01, 2007 5:16 pm

When you unplugged to reset, make sure you also pull the CMOS battery and discharge the capacitors, by pushing the power button 10 times, holding it for a full 10 seconds the last time. Yes. THere are several fuses on the motherboard.

redmond · #11 Post by **redmond** » Sat Nov 03, 2007 12:48 pm

ok, so the primary issue of the blown fuse is solved through a local hardware repair shop. how much should a fuse cost? i was told 2-3 fuses were blown that were replaced. is it possible for me to buy the fuses on my own?

now on to the bigger problem for which i was tinkering with my T43 in the first place. after 30 mins - 1 hour of use, the thinkpad auto shuts off. i am fairly sure this is due to heating because if it is taken apart and open it runs for a long while. i tried the usual things (replacing the goo on the processor etc) but it still shuts off.

i am quite disheartened that an expensive machine is unusable.

any ideas?

sktn77a · #12 Post by **sktn77a** » Sat Nov 03, 2007 9:49 pm

Is it a T42P or T43? Is it still under warranty. The two likely culprits are heat (get Notebook Hardware Control - NHC - and check your temperatures) or the dreaded solder flow problem where the solder joints (particularly at the graphics chip on the T42 series) give out.

I hope its the former!

redmond · #13 Post by **redmond** » Sun Nov 04, 2007 3:18 am

It is definitely a heating issue, I have checked the temperature but I am lost on how to resolve it. Right now the laptop is at a local hardware repair shop and they are having a hard time fixing it as well.

If I open up the laptop and run it so that the processor can get lots of air and doesn't heat up, then the laptop runs without any issues.

Does the solder flow problem have the same symptoms? i.e. laptop shutting off after 30 mins - 1 hour of use.

Also, after it shuts off I have to unplug the battery and the power and replug it in for me to be able to power it up again. Maybe this helps diagnose the issue.

sktn77a · #14 Post by **sktn77a** » Sun Nov 04, 2007 5:38 pm

redmond wrote:Does the solder flow problem have the same symptoms? i.e. laptop shutting off after 30 mins - 1 hour of use.

Well, not typically. And it can frequently be mitigated by physically pushing on the graphics chip while booting up with the computer open. What was the temperature of the CPU and the GPU?

redmond · #15 Post by **redmond** » Mon Nov 05, 2007 4:59 am

The computer is at a local repair shop and I don't remember exactly what the temperature was (If I recall correctly it was around 58 or something for the GPU). In any case, the repair guy has told me he will try and run it with another heatsink fan to check if that works and get back to me in 2-3 days.

awolfe63 · #16 Post by **awolfe63** » Tue Nov 06, 2007 11:15 pm

I had this with my first T42. It was new - so IBM fixed it. I'm not sure how - they just said bad fan. I think it was poor heatsink contact.

The reason I knew it was a thermal problem was I ran MOBmeter all the time and I could see the temperature go up to 90C each time before it conked out. Try that.

T42 not powering up after assembling it back together

T42 not powering up after assembling it back together

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