XO Immersion Repair: Difference between revisions

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(New page: 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 completel...)
 
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==Summary==
==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.
After immersion in flood water for several days, an XO laptop should be completely discarded, with the possible exception of the display. Even if components continue to function, it is very likely that they will fail in the near future.


==Description==
==Description==
Line 8: Line 8:


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.
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.

⚫
===Display===

The display showed serious corrosion on the backlight cable, and minor corrosion on the main display cable. After replacing the backlight (due to cable corrosion, the actual lightbar appeared fine), the display functioned correctly!
<gallery widths="320px" heights="240px" perrow="2">
Image:XO_Immersion_Repair_Display1.JPG|Backlight cable
Image:XO_Immersion_Repair_Display2.JPG|Display cable
</gallery>


===Battery===
===Battery===
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.
<gallery widths="320px" heights="240px">

[[image:XO_Immersion_Repair_Bat1|thumb|left|Battery contacts]]
Image:XO_Immersion_Repair_Bat1.JPG|Battery contacts
[[image:XO_Immersion_Repair_Bat2|thumb|left|Laptop battery contacts]]
Image:XO_Immersion_Repair_Bat2.JPG|Laptop battery contacts
</gallery>


===Motherboard===
===Motherboard===


Upon disassembly, it was determined that the motherboard was seriously oxidized. The worst damage was to the power supply units (1183, 1190, 1185, 1189) and the WLAN (1186, 1188)
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:
<gallery widths="320px" heights="240px" perrow="2">
Image:XO_Immersion_Repair_MB2.JPG|Battery charger
Image:XO_Immersion_Repair_MB3.JPG|Closeup of Battery Charger IC
Image:XO_Immersion_Repair_MB4.JPG|Backlight Power Supply
Image:XO_Immersion_Repair_MB5.JPG|+1.2V Supply
Image:XO_Immersion_Repair_MB6.JPG|WLAN module
Image:XO_Immersion_Repair_MB7.JPG|WLAN module and +3.3V Supply
</gallery>


One of the RTC battery holder contacts was seriously corroded (1184).
One of the RTC battery holder contacts was seriously corroded:
<gallery widths="320px" heights="240px" perrow="3">
Image:XO_Immersion_Repair_MB1.JPG|RTC Battery Holder
</gallery>


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:
<gallery widths="320px" heights="240px" perrow="2">
Image:XO_Immersion_Repair_MB8.JPG|Backlight Conn.
Image:XO_Immersion_Repair_MB9.JPG|Backlight Conn.
</gallery>


===Laptop Bottom===
===Laptop Bottom===


Opening up the bottom of the unit, the "hidden" battery connector showed serious corrosion on one pin (1196).
Opening up the bottom of the unit, the "hidden" battery connector showed serious corrosion on one pin.
<gallery widths="320px" heights="240px" perrow="2">
Image:XO_Immersion_Repair_Bat3.JPG|Backlight Conn.
</gallery>


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)
The connector between the KBC and the cable going to the motherboard showed only surface (non-contact) corrosion. The KBC itself only showed minor corrosion on the KBC chip.
<gallery widths="320px" heights="240px" perrow="2">
Image:XO_Immersion_Repair_KBC1.JPG|KBC/MB cable
Image:XO_Immersion_Repair_KBC2.JPG|KBC chip
</gallery>


===Keyboard===
===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
The keyboard showed corrosion on the flex cable connecting to the Keyboard Controller (KBC) PCB (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 and the V key.
<gallery widths="320px" heights="240px" perrow="2">
corrosion between the membranes under the space key (1201, 1202) and
Image:XO_Immersion_Repair_KB1.JPG|Keyboard flex cable
the V key (1203)
Image:XO_Immersion_Repair_KB2.JPG|Keyboard bottom membrane (space)

Image:XO_Immersion_Repair_KB3.JPG|Keyboard top membrane
⚫
===Display===
Image:XO_Immersion_Repair_KB4.JPG|Keyboard bottom membrane (V)
</gallery>


[[Category:hardware]]
The display showed serious corrosion on the backlight cable (1204), and
[[Category:repair]]
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.

Latest revision as of 19:44, 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 display. 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.

Display

The display showed serious corrosion on the backlight cable, and minor corrosion on the main display cable. After replacing the backlight (due to cable corrosion, the actual lightbar appeared fine), the display functioned correctly!

  • Backlight cable

    Backlight cable

  • Display cable

    Display cable

Battery

The battery contacts showed minor corrosion, but not in areas where the electrical connection is actually made.

  • Battery contacts

    Battery contacts

  • Laptop battery contacts

    Laptop battery contacts

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:

  • Battery charger

    Battery charger

  • Closeup of Battery Charger IC

    Closeup of Battery Charger IC

  • Backlight Power Supply

    Backlight Power Supply

  • +1.2V Supply

    +1.2V Supply

  • WLAN module

    WLAN module

  • WLAN module and +3.3V Supply

    WLAN module and +3.3V Supply

One of the RTC battery holder contacts was seriously corroded:

  • RTC Battery Holder

    RTC Battery Holder

The main connection to the display was relatively OK, but the backlight connector contacts were seriously corroded:

  • Backlight Conn.

    Backlight Conn.

  • Backlight Conn.

    Backlight Conn.

Laptop Bottom

Opening up the bottom of the unit, the "hidden" battery connector showed serious corrosion on one pin.

  • Backlight Conn.

    Backlight Conn.

The connector between the KBC and the cable going to the motherboard showed only surface (non-contact) corrosion. The KBC itself only showed minor corrosion on the KBC chip.

  • KBC/MB cable

    KBC/MB cable

  • KBC chip

    KBC chip

Keyboard

The keyboard showed corrosion on the flex cable connecting to the Keyboard Controller (KBC) PCB (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 and the V key.

  • Keyboard flex cable

    Keyboard flex cable

  • Keyboard bottom membrane (space)

    Keyboard bottom membrane (space)

  • Keyboard top membrane

    Keyboard top membrane

  • Keyboard bottom membrane (V)

    Keyboard bottom membrane (V)

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