Lenovo G505s No Power

[leggot]

Hi,

I have a Lenovo G505s that currently won't start, I believe that it is a power circuitry issue, however I am not 100% sure.

Initially the unit would boot but not charge the battery, despite the battery maintaining a charge, and the laptop would not run off the battery. This led me to believe that the MOSFET PQ302 was not working, hence I replaced it. This rendered useless, and shortly thereafter, I was recommended to heat the area to ensure there are no solder cracks. I heated both sides of the board in the area containing the power circuitry only. After this, the board seemed to have failed as there are no led lights and it won't boot.

I tested the voltage input, at 20v and the same voltage on PQ301 (pins 8 and 1) and PQ302 (pins 8 and 1).

Here is the service manual (battery circuitry is on page 48): https://drive.google.com/file/d/0BwBeBHAY_5iFSFZPUXpDekNZQlU/view?usp=sharing



I am not sure what to do next.

 

[Harald Kapp]

Your link is not accessible (at least not to me).

 

[leggot]

Sorry, please try this link: https://www.mediafire.com/?n2cgj4ry32swdd2 and page 39

 

[Harald Kapp]

What is the voltage on B+ (Pin 4 of PR301)?
PR301 is a Kelvin-connected current sense resistor. It may have opened due to overcurrent.
Also check CHG_B+ at the right side (pin 2) of PL301.
What is the voltage at pins 1 and 4 of PR324?
PQ309 and PQ310 together wit PU301 and PL302 make a switch mode regulator. If you don't see a good voltage on Batt+, probably this regulator is defect.Debugging a switch mode regulator is no easy feat.

 

[leggot]

Hi,

The voltages are as follows:

PR301 shows 0Ω
PR301- 20v on both sides
PL301(pin 2) - 0V
PR324 shows 0.3Ω
PR324 is 20.6V on both sides

I am fine with spending the time to debug the regulator, but if its just easier to pick several pieces to replace, thats fine with me too.

It appears as if PQ302 is SI4483A instead of AO4423L as indicated on the diagram. Not sure if this is the issue.

Thanks