I'm trying to help the OP at the following thread:
http://forum.hddguru.com/fried-pcb-n...ip-t24422.html

I'm fairly certain that the problem is a shorted TVS diode, but I'm
curious as to the identify of a 16-pin chip with the following
markings:

6855A
TI 271
A1CJ

It is located just below the 4-pin jumper block, and at about 10
o'clock to the MCU (the largest IC).

I suspect that it was made by Texas Instruments, and that it may be a
step-down PWM regulator with integrated MOSFET and diode.

A datasheet search at TI's web site found no items containing "6855".

The board appears to have 5 switchmode supplies (there are 5
inductors), with one being a -5V supply and the others probably being
positive step-down regulators. One would provide +1.8V for the SDRAM
and flash memory, while the others would provide the Vcore and Vio
supplies for the MCU.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.