I successfuly repaired this Lenovo Ideapad 320 laptop with board id NM-B242 Rev 1.0. According to customer, they used universal charger and set to 24V causing the laptop not to power on because of overvoltage.
I check for shortage using power supply but it has zero ampere. I dismantled the unit and check if there was a burnt components, but the board was clean and shinny.
I check 19V rail. I measure voltage input of the first mosfet, it has 19V. But on the output side, it has zero volt. I thought the culprit was the 2nd mosfet. But before I checked the 2nd mosfet, i disconnected the jumper PJ301. Then measured the output of the second mosfet if it has 19V. YES, it has! Therefore the problem lies on 19V rail.
So, I downloaded the schematics, and check the 19V rail. By analysing the schematic diagram under page 53, I planned to lift PQ314 hoping that this mosfet was leaking. I lifted the mosfet, then checked 19V at current resistor PR301. Huwaw!!! 19V was there! I quickly replaced PQ301 N-Channel type mosfet. Now the laptop has been revived.
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