hp probook 4520s power problem

[JustX]

hello.
i failed to find the problem with this laptop so im asking for a help
i have 19v on source and gate of the first mosfet and no voltage on drain. the things that i did till now checked the gate source it comes from q1 i dont have any voltage on adp_en pin 5
i changed q1 and kbc and bq24740
i made a jumper from source and drain next fet does its job and power button blinks white one second and then dosent do anything i dint have 3.3 and 5 i changed rt8205 and the same.
any ideas anyone

[ktmmotocross]

Re: hp probook 4520s power problem

did u check if u have short to ground after sensing resistor?

[JustX]

Re: hp probook 4520s power problem

yes i dont have short
schematics attached

[ktmmotocross]

Re: hp probook 4520s power problem

u have tricked PSU cable or u r using original HP charger?

[JustX]

Re: hp probook 4520s power problem

u have tricked PSU cable or u r using original HP charger?

i tried both with hp charger and power dc power supply i had no amper from device only at the beggining when i connect i see 0.01 current and then 0 and nothing happens

[Spider1211]

Re: hp probook 4520s power problem

is 3VL present when you added the jumper?

Remove the jumper and measure voltage on all pins of BQ24740 and report back. Also check if any mosfet is shorted (U50, Q29, Q30, U21, U17)

[ktmmotocross]

Re: hp probook 4520s power problem

i suggest to not relay on the repair, but to trick it. cheap laptop, time consuming search.

BUT
What about U65 ? dont see its reading from u

As i see u must have VCC1_PWRGD and ADP_EN signal to pull down base on first mosfet through Q1

And offcourse u must check charging circuit and +3VL

This circuits was pain in the ass

[kotar]

hello.
i failed to find the problem with this laptop so im asking for a help
i have 19v on source and gate of the first mosfet and no voltage on drain. the things that i did till now checked the gate source it comes from q1 i dont have any voltage on adp_en pin 5
i changed q1 and kbc and bq24740
i made a jumper from source and drain next fet does its job and power button blinks white one second and then dosent do anything i dint have 3.3 and 5 i changed rt8205 and the same.
any ideas anyone

I also have same error with you . and I do same things like you. Now I have Very Hot on( R306 ) it's 100 ohms no short to ground. what do i do ?