Lenovo T570 not turn on

[arber1232]

hello I have a lenovo t570 laptop that has water on board. I cleaned the board well with solutions for the board, dried it well and tried to turn it on, but it didn't turn on. I made some measurements 20v is the voltage in dc in and in the first mosfet I miss VSYS 3.3v and 5v
Laptop have 2 dcin i use type c charger i try and lenovo charger with with a yellow head

THIS IS SHCEMATIC




[Mod. Edit-Vesko356] Schematic: https://www.badcaps.net/forum/showthread.php?t=118676

[mon2]

Re: Lenovo T570 not turn on

Check the voltage to ground of PU7301:

pin #1 (VBUS)
pin #2 (ACN)
pin #3 (ACP)
pin #4 (CHRG_OK)
pin #28 (REGN)

[arber1232]

Re: Lenovo T570 not turn on

pin #1 (VBUS)=20.23v
pin #2 (ACN)=20.23v
pin #3 (ACP)=0v
pin #4 (CHRG_OK)=0v
pin #28 (REGN)=6v

[mon2]

Re: Lenovo T570 not turn on

pin #3 (ACP)=0v

Confirm this voltage to ground measurement. It should not be 0v unless there is a trace break or a resistor is missing between pin #3 of the charger IC and the current sense resistor @ PR7320 (pin #1).

To check the resistance, remove all power -> meter in resistance mode (lowest scale).

Measure the resistance with one probe @ pin #3 of the charger IC; other meter probe @ pin #1 of PR7320. If you do not see a low resistance (~10 ohms), there is a fault in this trace.

[arber1232]

Re: Lenovo T570 not turn on

yes is 10 ohms

[mon2]

Re: Lenovo T570 not turn on

Then the voltage on pin #3 should not be 0 volts -> confirm it. Should be the same voltage as the ACN pin.

[arber1232]

Re: Lenovo T570 not turn on

I measured it now with a device with thinner pins and the voltage is 20v

[mon2]

Re: Lenovo T570 not turn on

Measure the voltage to ground of VSYS (pin #22) on the charger IC.

Measure the voltage to ground of RTCVCC.

[arber1232]

Re: Lenovo T570 not turn on

i see in this place is not normaly can you confirm it ?

[arber1232]

Re: Lenovo T570 not turn on

VSYS 12.36v
RTCVCC 3v is battery bios ?

[mon2]

Re: Lenovo T570 not turn on

The mosfet is a P-channel so this means that the gate voltage must be lower than the voltage being passed between the source / drain pins to ENABLE.

Since gate voltage is the same, this mosfet is OFF.

Take a piece of wire and connect one side to pin # 4 (only) = GATE. Other side of the wire to ground on the logic board.

This act will force this P-channel mosfet to turn ON.

Test it.

[arber1232]

Re: Lenovo T570 not turn on

yes it true mosfet enable

[arber1232]

Re: Lenovo T570 not turn on

in Pu7501 VIN vsys is missing

[mon2]

Re: Lenovo T570 not turn on

Have you tried the ground wire on gate pin #4 of PQ7308?

[arber1232]

Re: Lenovo T570 not turn on

yes i try and mosfet enable now in Pu7501 i have
Vin=12,3v
Vreg3=3,3v
vreg6=5v
In power button i not have 3,3v

[mon2]

Re: Lenovo T570 not turn on

Check the voltage to ground on both sides of the fuse F2607 which is used to power the power switch board.

[arber1232]

Re: Lenovo T570 not turn on

is ov in both side

[mon2]

Re: Lenovo T570 not turn on

VCC3M is created by PU7501.

Remove all power. Meter in resistance mode.

Check the resistance to ground of VCC3M at PL7502.

What is the resistance?

Next, meter in voltage mode. Check the voltage to ground of the EN1 and then EN2 pin of pu7501. Each pin is used to enable the local power rails. We are checking to see if the power rail is being instructed to turn on or not.

[arber1232]

Re: Lenovo T570 not turn on

Risistance in Pl502 is 5,4 kohms
EN1=0.025 v
En2=0,025 v

[mon2]

Re: Lenovo T570 not turn on

Confirm the power rails of the KBC component that is used to enable the above power rails.