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 Post subject: Reflowing a T40p
 Post Posted: Mon Dec 05, 2011 7:19 pm 
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Hi Scott-

I have an older ThinkPad T40p. The USB ports stopped working a while ago. After some surfing around, I learned that sometimes, due to flexing of the mobo, the soldering points around the chipset get weak so that they don't pass current. Then things like the USB ports stop working. I got a CardBus USB adapter and that made it work for a while.

I recently dropped it and now it starts up sort of intermittantly. I turn on the start button. The lights come on as usual, but it ends up just the battery light and the little circular light with a cockeyed "Z" (to the left of the battery light) just stay on and nothing else happens.

One thing that sometimes works to get it going is this. I flex the bottom part of the laptop (the part with the keyboard). This, I assume, is flexing the motherboard and possibly realigning and reconnecting (temporarily) the soldering points. If it works, just before the battery light and cockeyed "Z" lights come on steady, I hear the DVD drive spin up and the light on the drive blinks on and off. Then the initial splash screen comes up and everything boots up as normal.

Sometimes it take a few trys, but it eventually works. If I move the system, or if enough time goes by, the system eventually freezes. Obviously this can't go on forever.

I bought an E420 and boy am I happy with it. I was influenced by some of the threads I saw on your site about ThinkPads and I have to thank you for it.

Well, now I don't care so much about the old T40p, although I am still fond of it, and it's still nice having an extra computer around. I saw some videos on YouTube about reflowing boards, and I thought it might be fun to try it.

What do you think about it?

Bob


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 Post subject: Re: Reflowing a T40p
 Post Posted: Mon Dec 05, 2011 7:36 pm 
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At this point, considering that you aren't dependent on the system, I'd most definitely give it a try. I've learned a lot from experiments like that, and you don't really have anything to lose. Please let me know the outcome. Thanks, Scott.


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 Post subject: Re: Reflowing a T40p
 Post Posted: Tue Dec 27, 2011 10:56 pm 
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There are a lot of strategies for heating and cooling of the motherboard. Most say to heat the board up to 385 degrees Fahrenheit for 8 minutes then to open the door and let it cool down for 30 minutes before touching it. Some heat the oven as high as 420 degrees.

I chose to heat the oven up to 385 degrees, wait 4 minutes, turn the oven up to 420 degrees, wait 4 minutes, shut off the heat and open the door for the oven to cool down. After 30 minutes of cooling off I figure it will be save to handle the board. I used an inexpensive internal oven thermometer along with an oven with a glass door to verify that temperatures were correct. Temperatures were pretty much right on the money.

Many people wrap the plastic parts of the board up with aluminum foil to protect it from the heat. My thinking is that if the temperature of the air in the oven is hotter than the board, aluminum foil is only going to draw heat to whatever you wrap it around rather than away from it. Lots of people don't wrap the plastic parts of the board, and I haven't read of any plastic parts on any boards melting. So I chose not to wrap anything with aluminum foil. Nothing melted.

One thing that I did learn is that you should be very careful about how you support the board. This is something that none of the sites I found warned me about. Most people support the board above a cookie sheet by supporting it with aluminum foil "balls". The foil "balls" are just rolled up balls of aluminum foil about 1/2 an inch thick.

I chose to support my board with 6 nuts locked around the ends of 3 screws laid upon a cookie sheet. This held the board about 1/2 inch above the cookie sheet. The screws were toward the center of the board. Unfortunately, the board warped due to the uneven support in the center of the board. After the board cooled down, I foolishly tried to straighten out the board by flexing it with my hands. I heard a crackling noise as I did so. Probably the sound of hundreds of soldered joints fracturing.

I am assuming this ruined the board and I will try "cooking" the board again using all the available holes in the board to support the board with nuts and screws. Also, I will find something more flat to support the screws than a cookie sheet. I will probably use an upside down turned glass casserole dish, since they can be really flat on the bottom.

I doubt this will restore the board to it's original shape, I suspect that when I install the recooked board into the laptop it will flex the board again and fracture the soldering contacts all over again. Oh well, nothing ventured, nothing gained.

Presently, I am waiting for the right size nuts and screws to come in the mail (I had to order them). When I get them, I will try again and post the results here.


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 Post subject: Re: Reflowing a T40p
 Post Posted: Wed Dec 28, 2011 12:11 pm 
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Thanks for the detailed update! Please keep me posted on the outcome. Scott.


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 Post subject: Re: Reflowing a T40p
 Post Posted: Sun Jan 01, 2012 2:44 pm 
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I am dumbfounded. It seems to have worked.

Just to go over what I did.

I peeled a number of plastic tape off the board before putting it in the oven. I saved all the plastic and was careful to preserve the shape of them while taking them off. Later I taped pieces of electrical tape to waxed paper. Then I used the old pieces of plastic as stencils as I cut out new pieces with a razor blade from the electrical tape. I don't know what those pieces of plastic were for. I can only assume they keep exposed parts of the board from coming in electrical contact with other exposed parts of the computer. I also took pictures with my digital camera of the pieces before I took them off, so I'd know where to put them back on.

I supported the board with a number of 2mx14mm bolts with nuts on either side of the board to hold it in place. The board was pretty warped. I straightened it out a little more before cooking it. It still wasn't very straight, but it was the best I could do. I used an old bread board to rest it on while in the stove. It was pretty flat, so I thought it would not contribute to the warping of the board again. The bread board was a little more dark afterward, but not black, and not warped and even still usable.

I heated the oven the same as above. I was surprised that the system board was pretty much flattened out into it's original shape. There were a few bolts that were not touching the bread board surface, but they weren't more than 1/16th of an inch above the it.

I put the system back together and it booted right up. I backed up a DVD just to put some stress on it to see if it would fail and it didn't. Even the USB ports are working again. I transfered a 4GB file and didn't have any trouble.

As I was putting the system back together again I noticed that several of the threaded recesses in the palm rest which one screws things into were damaged. I think that this caused the initial problem with the board. The housing of the laptop wasn't rigid enough to keep the system board from flexing. Which is what I think caused the solder joints to weaken in the first place.

I bought a new palm rest and now the laptop external housing feels a lot stiffer. Hopefully the board will not fail soon due to this type of problem.

The sites that I've visited claim that this type of fix is not very permanent. They warn that this type of fix may last anywhere from 2 weeks to a year. I had this working 12-30-2011. When the board fails, I'll look up this post again and post when if fails again here.

I suspect a common reason laptop motherboards fail in this way is because people lose the screws or over-torque them when reassembling their laptops. If they over-torque the screws the inner threaded portion of the laptop fails and the laptop (and motherboard) is subject to a lot more flexing. Maybe the reason that this kind of fix is so unreliable is that people never address the cause of the problem in the first place: leaving out screws. I bought a screw kit for the laptop and I have made sure all the screws are in and not over-torqued.

Right now the lower portion of the laptop housing seems much firmer than before. I'm hoping that it may last a long time.


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 Post subject: Re: Reflowing a T40p
 Post Posted: Sun Jan 01, 2012 3:59 pm 
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Thanks for reporting the final outcome, I'm glad that it actually worked out!

To solve the flexing problem Lenovo incorporated a "Roll Cage" design in most ThinkPads starting in 2005. Scott.


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 Post subject: Re: Reflowing a T40p
 Post Posted: Wed Oct 02, 2013 1:30 pm 
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It is now starting up intermittently as I described in the beginning of this thread. It worked for almost 2 years.

I am very used to the SXGA+ (1400x1050 or 4:3) display standard. I'm considering getting a T60 as a replacement.


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 Post subject: Re: Reflowing a T40p
 Post Posted: Wed Oct 02, 2013 4:52 pm 
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I still have an R60 with that display that I use as a utility/auxiliary computer. The only problem is that the backlight has always been very dim. I much prefer the brighter LED backlight on my T520.


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