Reassembled XOs fail heat spreader test

[Sridhar Dhanapalan]

All of the XOs I've seen have three screws on their heat spreaders.
I've attached an annotated image. Hopefully the lists don't strip it
out.

There is an unanchored screw point in the bottom-left. However, the
danger area is at the top, particularly in the top-left. This affects
contact between the heat spreader and the Companion Chip, and might
also be affecting contact with the CPU. Do the four-screw versions of
the heat spreader address this problem?

Thanks,
Sridhar



On 23 July 2011 01:21, John Watlington <wad at laptop.org> wrote:
>
> Do your heat spreaders have four screws or three ?
>
> The final heat spreader for XO-1.5 production had four screws
> holding it down, to ensure a good fit.    If your heat spreaders
> only have three, OLPCA should be able to get proper replacements
> from Quanta.
>
> Regards,
> wad
>
> On Jul 22, 2011, at 10:35 AM, Sridhar Dhanapalan wrote:
>
>> We are currently engaged in changing the motherboards in over a
>> hundred XO-1.5s. In many cases, the XOs are failing the heat spreader
>> test afterwards.
>>
>> However, we can get the test to pass if we press down on the lid,
>> behind the screen. This suggests to me that the heat spreader is not
>> in proper contact with the chips.
>>
>> Without the lid plastic affixed (heat spreader exposed), we can see
>> that the spreader is not touching the chips properly. We have tried
>> bending the metal slightly near the screw points, but the contact
>> doesn't last.
>>
>> Is there any way that we can deal with this better? We are changing
>> the motherboards in these XOs because they have succumbed to
>> overheating. I want to avoid that from happening again.
>>
>> Thanks,
>> Sridhar
>>
>>
>> Sridhar Dhanapalan
>> Engineering Manager
>> One Laptop per Child Australia
>> M: +61 425 239 701
>> E: sridhar at laptop.org.au
>> A: G.P.O. Box 731
>>      Sydney, NSW 2001
>> W: www.laptop.org.au
>> _______________________________________________
>> Devel mailing list
>> Devel at lists.laptop.org
>> http://lists.laptop.org/listinfo/devel
>>
>
>
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