On Thu, 7 Feb 2013 14:28:54 -0500, "Wild_Bill"
put finger to keyboard and composed:

D7 may not be across the DC supply, and not have anything to do with the T3
failure.. that's up to the person testing the unit to determine.

I'm guessing that D7 is a Schottky diode. I suspect that D7, L4
(6.8uH) and U16 form a buck regulator that generates the +5V supply. I
can't see any reverse polarity protection on the PCB, so I would think
that U16 would have been hit.

The L2 and L3 coils are probably associated with U17 and U14 to form
their own +1.8V and +3.3V buck regulators. I suspect that each of
these ICs would have been hit also.

If I were the OP, I would locate the datasheets for the three ICs and
examine their application circuits, if any.

- Franc Zabkar
--
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