Reassembled XOs fail heat spreader test
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: srid...@laptop.org.au A: G.P.O. Box 731 Sydney, NSW 2001 W: www.laptop.org.au ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Reassembled XOs fail heat spreader test
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: srid...@laptop.org.au A: G.P.O. Box 731 Sydney, NSW 2001 W: www.laptop.org.au ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Reassembled XOs fail heat spreader test
The unused hole actually is filled by one of the screws which holds in the rear plastic panel. That's why the screw holes which only secure the heat spreader have arrows pointed at them. The fanciest (newest?) XO-1.5 heat spreader design I've seen adds a support bar up to the green screw hole above near your area of concern, again filled by a screw used to secure the back cover. I'm not certain though if this is the design John is referring to, but I have seen a few XO-1.5s with it. It may be possible to bend the existing heat spreader in a certain manner which solves the problem. But I would *not* be someone who could recommend this approach for deployments. Some of OLPC's hardware engineers may be traveling this weekend, so I'm just trying to provide you with a quick explanation in the meantime. On Fri, Jul 22, 2011 at 9:55 PM, Sridhar Dhanapalan srid...@laptop.org.auwrote: 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 w...@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: srid...@laptop.org.au A: G.P.O. Box 731 Sydney, NSW 2001 W: www.laptop.org.au ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Reassembled XOs fail heat spreader test
Thanks Samuel. I'll be talking in more depth with OLPCA about this. Any suggestions on how to deal with this in the meanwhile are welcome :) I have found that it can help to bend the spreader near the screw points to make it slightly concave. However, I agree with you that this is not a good recommendation for deployments. Sridhar On 23 July 2011 12:18, Samuel Greenfeld greenf...@laptop.org wrote: The unused hole actually is filled by one of the screws which holds in the rear plastic panel. That's why the screw holes which only secure the heat spreader have arrows pointed at them. The fanciest (newest?) XO-1.5 heat spreader design I've seen adds a support bar up to the green screw hole above near your area of concern, again filled by a screw used to secure the back cover. I'm not certain though if this is the design John is referring to, but I have seen a few XO-1.5s with it. It may be possible to bend the existing heat spreader in a certain manner which solves the problem. But I would *not* be someone who could recommend this approach for deployments. Some of OLPC's hardware engineers may be traveling this weekend, so I'm just trying to provide you with a quick explanation in the meantime. On Fri, Jul 22, 2011 at 9:55 PM, Sridhar Dhanapalan srid...@laptop.org.au wrote: 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 w...@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: srid...@laptop.org.au A: G.P.O. Box 731 Sydney, NSW 2001 W: www.laptop.org.au ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
