Lenovo G500 - No power or charging

[panandreas]

Hi everybody,

I have a Lenovo G500 with LA-9631P mobo that doesn't turn on. If I connect the laptop to AC power I get no lights or anything that shows that its on a power outlet. Same thing happens if I press the power button.

I have found some information and schematics on the internet about the laptop and I started measuring Voltages with a multimeter. I have power (20.31V) getting in the mobo but no 3.3V or 5V.

From the info I have found this laptops has problem with the FETs on the charging circuit. So I measured the voltages on the first FET after the VIN which is PQ301 (A04407AL) and the measurements are:

• Drain(5,6,7,8): 20.31V
• Source(1,2,3): 19.78V
• Gate(4): 19.77V

Is this normal? Shouldn't the gate has a lower voltage? Shouldn't the voltages between drain and source be almost the same?

Do you think this is the problem of my laptop or do you have a suggestion for anything else that could be the problem?

I am attaching some schematics images

Thanks for your time

[r0ma1992]

Re: Lenovo G500 - No power or charging

I think PQ301 or PQ302 is damaged. Check resistance between Source and Gate. There is should not be a short circuit

[panandreas]

Re: Lenovo G500 - No power or charging

Unfortunately there is no short circuit between source and gate and that's why I have opened this thread. I am measuring about 200 Kohm which is the resistance of PR304

[lakrouf]

Re: Lenovo G500 - No power or charging

PQ301 P CH is damaged change it.

[panandreas]

Re: Lenovo G500 - No power or charging

I will try to replace PQ301 and report back. Thank you very much

[peste]

Re: Lenovo G500 - No power or charging

if you have to point B + 19v is ok ... if you did not, change pq 301, pq302, pu301, check pr301, power button.