XO Immersion Repair: Difference between revisions
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===Battery=== |
===Battery=== |
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The battery contacts showed minor corrosion, but not in areas where the electrical connection is actually made. |
The battery contacts showed minor corrosion, but not in areas where the electrical connection is actually made. |
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[[image:XO_Immersion_Repair_Bat1.JPG|thumb|center|Battery contacts]][[image:XO_Immersion_Repair_Bat2.JPG|thumb|center|Laptop battery contacts]] |
[[image:XO_Immersion_Repair_Bat1.JPG|thumb|center|Battery contacts]][[image:XO_Immersion_Repair_Bat2.JPG|thumb|center|Laptop battery contacts]] |
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===Motherboard=== |
===Motherboard=== |
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Upon disassembly, it was determined that the motherboard was seriously oxidized. The worst damage was to the power supply units |
Upon disassembly, it was determined that the motherboard was seriously oxidized. The worst damage was to the power supply units and the WLAN. This was likely due to the battery keeping the VIN rail powered during the immersion: |
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[[image:XO_Immersion_Repair_MB2.JPG|thumb|center|Battery charger]][[image:XO_Immersion_Repair_MB3.JPG|thumb|center|Closeup of Battery Charger IC]] |
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[[image:XO_Immersion_Repair_MB4.JPG|thumb|center|Backlight Power Supply]] |
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[[image:XO_Immersion_Repair_MB5.JPG|thumb|center|+1.2V Supply]] |
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[[image:XO_Immersion_Repair_MB6.JPG|thumb|center|WLAN module]] |
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[[image:XO_Immersion_Repair_MB7.JPG|thumb|center|WLAN module and +3.3V Supply]] |
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One of the RTC battery holder contacts was seriously corroded |
One of the RTC battery holder contacts was seriously corroded: |
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[[image:XO_Immersion_Repair_MB1.JPG|thumb|center|RTC Battery Holder]] |
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The main connection to the display was relatively OK, but the backlight connector contacts were seriously corroded (1191, 1192) |
The main connection to the display was relatively OK, but the backlight connector contacts were seriously corroded (1191, 1192) |
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Revision as of 19:13, 1 October 2008
This is a failure analysis of an XO laptop which had been immersed in water for several days.
Summary
After immersion in flood water for several days, an XO laptop should be completely discarded, with the possible exception of the screen. Even if components continue to function, it is very likely that they will fail in the near future.
Description
OLPC received a laptop, CSN74800466, from a small school that had been flooded.
Upon receipt, the EC was operating (the battery LED indicated external power and battery charging), but the screen did not light up and no sound was heard on power up.
Battery
The battery contacts showed minor corrosion, but not in areas where the electrical connection is actually made.
Motherboard
Upon disassembly, it was determined that the motherboard was seriously oxidized. The worst damage was to the power supply units and the WLAN. This was likely due to the battery keeping the VIN rail powered during the immersion:
One of the RTC battery holder contacts was seriously corroded:
The main connection to the display was relatively OK, but the backlight connector contacts were seriously corroded (1191, 1192)
Laptop Bottom
Opening up the bottom of the unit, the "hidden" battery connector showed serious corrosion on one pin (1196).
The connector between the KBC and the cable going to the motherboard showed only surface (non-contact) corrosion (1198). The KBC itself only showed minor corrosion on the KBC chip (1200)
Keyboard
The keyboard showed corrosion on the flex cable connecting to the KBC PCB (1199, not in the contact area, but destructive given the nature of flex cable traces.) The keyboard matrix itself almost survived. There was a small amount of corrosion between the membranes under the space key (1201, 1202) and the V key (1203)
Display
The display showed serious corrosion on the backlight cable (1204), and minor corrosion on the main display cable (1205). After replacing the backlight (due to cable corrosion, the actual lightbar appeared fine), the display functioned correctly.