Difference between revisions of "XO4 C1 ECOs"
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Revision as of 23:53, 29 November 2012
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These are recommended engineering change orders (ECOs) to the C1 prototype of the XO-4 laptop. This is NOT a list of changes from C1 to C2, that is located elsewhere.
External SD Power Switch
There is a problem with the external SD power switch which prevents it from supplying +1.8V to the card. This can be fixed by:
- Replace R416, R417, and R420 with zero ohm resistors.
- Remove R414. Wire a 220K resistor between Q54, pin 3, and +3.3V_NAND. One location where this is readily available is PR102 (either end, above the battery connector and PU10).
- Remove C498
- Change R415 to 220K
- Change C420 and C496 to 0.1 uF
- Replace Q50, which has been removed, with an AO3402.
Modify the Board ID
Modify the board ID to 4C2 to communicate the new SD Power Switch capabilities to software:
- Change R337 ("bottom" side, near the EC) to a 33K resistor
Shorter version
This one has slightly longer turn-on/turn-off times, but otherwise works fine and halves the soldering required. The board ID should also be modified.
- Replace R416 and R420 with zero ohm resistors (anything less than 50 ohms will do).
- Remove R414. Wire a 100K resistor between Q54, pin 3, and +3.3V_NAND. One location where this is readily available is PR102 (either end, above the battery connector and PU10).
- Remove C498
- Replace Q50, which has been removed, with an AO3402.