Acer Aspire 3680 (Dead)

Acer Aspire 3680 (Dead)

   01:28       intersoft

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This unit comes in Wednesday with symptoms: DEAD
Will Not Charge
Will Not Work With Good Battery

Diagnosis begins by following the DC IN from the DC Jack. The voltage would drop to 3v and not enough to power laptop or close any gates on the MOSFETs.

Taking the MOSFET [FDS6675] source side out of circuit shows the direction of the shorted components. Since the power branches to the charge section or the run section with the other MOSFET shown below it. Checking to voltage at the source shows +19v. When in soldered on the board, the MOSFET DRAIN voltage is +3v. After replacing the FDS6675 the DRAIN side is still shorted.

Further testing indicates larger capacitor shown (in circle picture 1) is also shorted, removing it from circuit voltage on Drain side is now +19v. But the laptop would not turn on.

Still further testing and following the circuit path leads to the top side (facing technician when opened) to a series of three capacitors. Removing one side of this bank and testing each capacitor finds the shorted capacitor. As it turn out it was the topmost cap (marked with X in image), and when removed it was horizontally spit into 2 pieces.

Replace Capacitor.