T23 Freezes when picked up **I Found something**

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TomKroscavage · #1 Post by **TomKroscavage** » Sat Mar 31, 2007 1:07 am

I've pulled everything out except one stick of memory and I moved that around. I've put the motherboard under a spotlight and inspected it. Is there anything I can do or check before I throw it out?

****The coil on the top left side of the motherboard above the CPU has a broken solder joint.****

#2 Post by **rkawakami** » Sat Mar 31, 2007 2:05 am

When I have the time (and the inclination) to take one of the "blink of death" systems I have apart to look at the motherboard, then this is what I plan to do:

- using a dental pick and a magnifying glass, inspect each lead of every component which appears to be related to the power systems

As schematics are not available, that's the only solution I have. I could try hooking up an oscilloscope but that is kind of useless since I don't have a good system to compare against. (The dead systems are a T21 and T22). I've posted pictures of the T23 motherboard and referenced them in this thread:

http://forum.thinkpads.com/viewtopic.php?t=37956

If you give me a day or so, I can give you the approximate locations you can check.

TomKroscavage · #3 Post by **TomKroscavage** » Sat Mar 31, 2007 7:29 am

I'm thinking that since flexing the motherboard creates the problem the surface mounted fuses and resistors are transferring the force to the solder joints. They may be causing the freeze up because of their stiffness? Just a thought.

Website · #4 Post by **tfflivemb2** » Sat Mar 31, 2007 11:08 am

This was actually the symptom that I was having prior to this systemboard giving out in this sticky thread.

phool@round · #5 Post by **phool@round** » Sat Mar 31, 2007 11:41 am

Spirit-1776,

Is/was the upper or lower case cracked anywhere and if so where?

If you are using two memory modules are they both showing up in the BIOS, in the OS?

Does your backlight stay on when the computer freezes?

#6 Post by **rkawakami** » Sat Mar 31, 2007 11:52 am

Flexing the motherboard should put more strain on the larger surface mounted components which have a relatively smaller solder pad footprint. Prime example would be the graphics chip that uses BGA (ball grid array) packaging. The ceramic or plastic package of such a device is at least an inch square. Underneath, there can be a couple of hundred tiny solder balls which should be making contact to the pads on the motherboard. When force is applied to one side/corner of the package, the strain is transferred onto each one of those balls. Sure there are hundreds of them to spread out the pressure, but a round contact (the solder ball) against a flat surface (the motherboard pad) means that the overall contact point footprint can be pretty tiny.

Thermal expansion and contraction can also cause problems like this. Again, taking the graphics chip as an example, the heat/cool cycles generated by these parts over time can weaken the solder connections. Coupled with some of the early lead-free solders being used in the industry, some of which have been proven to weaken over time/temperature, can cause these types of failures.

Of course any kind of poor solder reflow during the assembly process (lack of solder paste, lack of proper temperature, contamination on the leads) can cause any part to break off from the motherboard. I don't think that fuses and resistors are more prone, than say capacitors and transistors. What seems to matter is the physical size of the component (bigger is worse) and its overall rigidity.

(ref: IEEE article on shear strength of lead-free solders)

TomKroscavage · #7 Post by **TomKroscavage** » Sat Mar 31, 2007 12:51 pm

phool@round wrote:Spirit-1776,

Is/was the upper or lower case cracked anywhere and if so where?

If you are using two memory modules are they both showing up in the BIOS, in the OS?

Does your backlight stay on when the computer freezes?

-The case is not cracked
-Memory always shows up in Both
-the back light stays on. XP or suse freezes no mouse no keyboard except the thinklight will toggle

TomKroscavage · #8 Post by **TomKroscavage** » Sat Mar 31, 2007 1:05 pm

phool@round wrote:Spirit-1776,

Is/was the upper or lower case cracked anywhere and if so where?

If you are using two memory modules are they both showing up in the BIOS, in the OS?

Does your backlight stay on when the computer freezes?

I forgot the soldered on spacer under the NIC closest to the MiniPCI broke off the motherboard at the solder joint about a year ago. I left it loose.

TomKroscavage · #9 Post by **TomKroscavage** » Sat Mar 31, 2007 1:18 pm

I FOUND SOMETHING! The coil on the top left side of the motherboard above the CPU has a broken solder joint.

phool@round · #10 Post by **phool@round** » Sat Mar 31, 2007 1:20 pm

That spacer or post is very close to the video chip.....hmmm. I wonder if that post has effected the video signal in any way. It would take some considerable flex in order to pop that post from it's solder......

I had an R50 that would freeze the display for the very reason Ray brought up about the solder joints under the video chip. But a component that is in the video signal path could effect it the same way........

There are a few electrical components soldered very near that post, touch up the solder on those both top and bottom and see what happens......

You'll need your light and magnification to see what tiny components I'm talking about.

phool@round · #11 Post by **phool@round** » Sat Mar 31, 2007 1:24 pm

On Ray's top diagram would that be the one that occupies the A1/2 area?

I had one also not post video but the power light and fan came on for the same reason.

Cool!

#12 Post by **rkawakami** » Sat Mar 31, 2007 2:08 pm

If you look closely on that photo of mine you will notice that the inductor is NOT there. I had to take it off that board to use on one system that arrived with it missing. "A1/A2" was one of the places I was going to suggest

.

dannydoo · #13 Post by **dannydoo** » Mon Apr 02, 2007 1:31 am

does anyone have pics of this?

#14 Post by **rkawakami** » Mon Apr 02, 2007 1:39 am

In the second post of this thread I have a link to another thread here. In it I have posted links to scans I've made of a T23 motherboard. The part that is being mentioned here is NOT in those scans because I had removed it to fix another board. If you look at the top side picture, just above the large white socket for the CPU, it would be in the area marked A1 and A2.

Here is the link to the scan:

Top side w/legend (158KB)

TomKroscavage · #15 Post by **TomKroscavage** » Tue May 08, 2007 11:37 pm

I soldered up the coil above the CPU but the computer still freezes up twice a day. There is a flat surface mounted component to the right of the coil that looks burnt up. I desoldered that part and tested it with my continuity tester and found a closed circuit in both directions no resistance. Does anyone know what this is?

#16 Post by **rkawakami** » Wed May 09, 2007 12:20 am

If you are talking about a thin, flat, black component with silver endcaps, then I believe that it's a fuse. It should read 0 ohms

.

TomKroscavage · #17 Post by **TomKroscavage** » Wed May 09, 2007 8:05 am

Thanks Ray. I have a motherboard I bought off ebay two years ago that is working perfectly. It was listed "as is" buy it now $15, but I would like to get the broken one going again.

T23 Freezes when picked up I Found something

T23 Freezes when picked up I Found something

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