XO 1.75 B1 ECOs

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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.

Enabling Antitheft

By mistake, the resistor which disables the OFW SPI Flash antitheft circuit (to allow for ISP reprogramming in the repair center) was populated.

• Depopulate R92

This has not been done on any motherboards.