XO 1.75 B1 ECOs
This page is monitored by the OLPC team.
These are recommended engineering change orders (ECOs) to the B1 prototype of the XO-1.75 laptop. This is NOT a list of changes from B1 to C1, that is located elsewhere.
Fix MPPT
This extends the range of input voltages which the MPPT algorithm can use.
- Change PR234 to 150K
- Change PR235 to 220K
This was done to most B1 units, with the exception of twenty-six or so. wad has the serial numbers of laptops missing this ECO.
Increase Bulk Decoupling
This fixes a problem seen on some boards where trying to turn it on results in two fast blink of the red battery LED, cycling indefinitely. The problem is due to the +3.3V power supply shutting down when loads are added suddenly.
- Populate PC54 w. a 22 uF, 6.3V cap (or higher). This should be a ceramic cap.
This has already been done to around a dozen motherboards, as needed for reliable booting.
