A
Lenovo Y450 laptop, remove the battery, connect the adjustable DC power
supply, the standby current is 0.059A, the value is higher than normal
one, Push the power button and the current up to 0.53A, then automatic
shutdown. Open the notebook, checked each inductance, find the
resistance is only about 130 ohm between PL6 5VPCU and GND. The normal
value should be more than 300 ohm.
There
is a little short circuit, but the laptop can trigger, so solve
automatic shutdown problem first. According to the previous maintenance
experience, usually it is 1.8V circuit problem, this voltage is for the graphics
card. So, connect power supply again to test, the 1.8V is normal when
automatic shutdown. ....read more
A Lenovo Y470 notebook, can not start up when connect power or using battery, The led of power adapter is flashing when connect power. Open the laptop, test the power input terminal with multimeter, there is not short circuit, then test B+ point, find short circuit, then test the mosfet PQ302, PQ302 was damaged, remove it and replace a new one. ... read more
