GPU problem on a T42

[Sudevan]

I had recently picked up a T41 and a T42 quite inexpensively, and gratefully, from Medessec, just so that I could tinker with the hardware and learn a few things. When they arrived the T41 worked fine and the T42 would not boot. Now this was exactly the opposite of what Medessec had told me -- that the T42 worked fine, but the T41 had display issues. No matter, this was the exact reason why I picked these machines up -- for tinkering. So, together with my tech friend Chuck and his collection of memory sticks, I first tried swapping memory, both the stick in the back and the one you get to after popping up the keyboard. Various combinations resulted in no progress.

Then I remembered reading something that George (ajkula66) had posted regarding this problem on the T4x machines. He suggested starting the machine while pressing down on the GPU chip. And it worked! Windows 7 came up without problems (nice high res screen too -- SXGA+ ? -- thank you Medessec! ). And thank you, George for this suggestion. When I released pressure on the chip from my finger, it beeped at me and the display went off. Our conclusion was that the GPU must very probably have come unsoldered from the motherboard during shipping. Reflowing it is not within our capabilities, so we are going to try another motherboard -- used ones are about $20 on fleabay, so we will give it a go. Yes, I have heard about baking the darn thing in an oven, but I am not sure I want to try that! My objective is not necessarily to make this machine perfect, but to get more comfortable with the hardware. My friend, who repairs laptops of all kinds, is of the opinion that Thinkpads are among the more difficult ones when it comes to motherboard replacements. I'll find out for sure when the thing gets here, and I have a first crack at it.

I am sure there are Forum members who have done things like re-soldering bits and bobs on these motherboards. Any advice on alternate approaches would be very welcome. My apologies if all this seems like old hat to many, but it is rather a new adventure for me.

As ever,

Sudevan

[theterminator93]

My thoughts upon reading the thread title before I opened it and read your post was "probably one where he can put pressure on the GPU to get it to boot".

If you are in the market for a replacement board, the later ones have red epoxy dabs on the board in key places on the edges of the GPU and chipset dies to help keep flex and chip creep down to a minimum. My T42p has one of these "red dot" motherboards and it's been fine since I've had it - though I don't use it particularly heavily. Either way - I'll take all the help I can get.

[that1nerd]

My friend, who repairs laptops of all kinds, is of the opinion that Thinkpads are among the more difficult ones when it comes to motherboard replacements.

Have they ever worked on MacBooks or iBooks before? Now THOSE are very difficult to service, let alone do a motherboard swap for.

IMO, the T4x series are about as difficult as any other laptop of the era, in some ways easier, and I've serviced quite a few different makes and models of laptops. Even if you get lost or confused, the HMM (Hardware Maintenance Manual) is a great resource of information for servicing these units.

As for reflowing chips, it requires specialized tools to do it properly, which I lack.

The idea is to preheat the board with some sort of hot-plate or oven, and then to use a hot-air gun on the chip in question. During the process, don't let the hot-air gun sit in one place for too long. Move it around slowly in a circular motion over the chip.

That's the gist of it, anyway. Probably makes more sense to just replace the board unless you're willing to experiment.

[RealBlackStuff]

Forget about reflowing the GPU or Southbridge (big Intel chip under the wifi-card).
Forum member poshgeordie used to do that for me, but I had to ship stuff to the UK and back for that.
He is no longer in that business and I never found a reliable partner in the US.
The red dots BTW are no guarantee that the chips will 'hold'.
Too many people pick up their laptops with one hand (usually on a corner), thus flexing the mobo to no end.

[Sudevan]

RBS, Thanks for the suggestions. The T41motherboard is on its way, so I will check to see if it has those red spots. This is perhaps a dumb question: Can one add the epoxy oneself? What I mean is, can one get some red epoxy and add it to the corners, etc., to strengthen things?

Once I get the T42 working again, I might take the non-working one we pull from it and go the baking plus hot-air gun route suggested by that1nerd, just for the heck of it, to see if it can be revived. If it works we can call it the Lazarus motherboard. Come to think of it, that's a nice name for a new line of Thinkpads, maybe even the new Retro TP that David Hill is going to build for all of us retrocomputing addicts. Rising from the dead, perfect for Halloween too. (Or maybe the Phoenix)

that1nerd, thanks for your comments. I think my pal fixed a 2000-era Macbook Pro someone had given me for free, which was having some trouble with the display. I can't remember what was wrong with it, precisely, but I am pretty sure he did not get a new motherboard. He did not seem to think that it was a hugely difficult fix either, but it did require some work to figure out what was wrong with it.

Cheers,

Sudevan

[Sudevan]

Sorry I should have addressed my first set of comments to theterminator93 as well. My apologies!

Sudevan

[RealBlackStuff]

Leave those epoxy dots to the factory (never heard of anyone doing them "aftermarket").

[Fotis]

I had the same issue on my t41p, and chose to replace the motherboard, which i think is the best choice. It took a couple of hours following the service manual. It was actually easier than I thought.

[Sudevan]

Thanks. I also realized just now that I had mis-typed: I should have said the T42 motherboard is on its way, not the T41! Once I install it, I will post here and let people know how it went.

Cheers,

Sudevan