B2 Suspend ECR

This page describes how to modify an XO B2 laptop to better support suspend/resume.

Keyboard Power

This ECR changes the power supplied to the keyboard and touchpad so that they are powered in suspend mode. In a B2 unit, the keyboard power comes from +3.3V, which is normally turned off in suspend. This ECR powers the keyboard from the SUS_3.3V supply.

1. Disassemble the laptop until the motherboard is exposed (the motherboard does not need to be removed, so the display may remain connected.)
2. Disconnect the cable going to the keyboard (CN23).
3. Rotate L37, an 0805 ferrite located very close to CN23, the keyboard connector, so that it is only connected by one pad (the one wired to L36, a non-populated 0805 adjacent to L37).
4. The other terminal of L37 (resting on the soldermask) should be wired with a blue wire to the center pin of Q26. Q26 is a three lead SOT-23 located halfway between the Southbridge (U27) and the EC (U41), immediately above the EC reset switch. The silkscreen legend identifying Q26 is part of block J, located near SDRAM U22 (nowhere near Q26 !).
5. Reconnect the keyboard cable and reassemble the unit.

Laptops Modified

The following laptops have already been modified, and sent out to developers. We are placing a green sticker labelled "PWR" in the battery compartment of these laptops.

• SHF70500391
• SHF70600283
• SHF70500240
• SHF70500358
• SHF70nnn27F
• SHF70nnn34A
• SHF70nnn392
• SHF70nnn3AA
• SHF70nnn3A0

Some of these serial numbers are incomplete (indicated by nnn digits). Please supply all digits if you know them!