HP Pavillion 15-cw1077nl no power

[vpower]

Hi, I have this laptop that is not powering on. It died suddenly. If I connect the charger or the power supply (19v), no charging led light is turning on.
I only checked with a multimeter that 19v is on the connector of the charging cable on the board (marked with an arrow on the "front" image).
Any hint? Cannot find any schemathics or board layout. Board code is DAG7BJMB8C0 REV C MODEL G7BJ
Regards,
Vito

[mon2]

Re: HP Pavillion 15-cw1077nl no power

Locate the power adapter connector. Start there to confirm the adapter voltage is present.

Continue to review the power path to the 2*DCin mosfets. These will be 8 pin devices.

Measure with care the voltage to ground of:

Source (1-2-3)
Gate (4)
Drain (5-6-7-8)

Pins of each of these mosfets. Post the measurements and also the topside markings of the mosfets.

Next, these mosfets are enable by the gate pin that will contain a ~4k resistor to the charger IC. The charger IC will be square in shape = qfn package.

What are the topside markings of the charger IC?

Do post pics of the mosfets and the charger IC for a verification.

[vpower]

Re: HP Pavillion 15-cw1077nl no power

Locate the power adapter connector. Start there to confirm the adapter voltage is present.

Continue to review the power path to the 2*DCin mosfets. These will be 8 pin devices.

Measure with care the voltage to ground of:

Source (1-2-3)
Gate (4)
Drain (5-6-7-8)

Pins of each of these mosfets. Post the measurements and also the topside markings of the mosfets.

Next, these mosfets are enable by the gate pin that will contain a ~4k resistor to the charger IC. The charger IC will be square in shape = qfn package.

What are the topside markings of the charger IC?

Do post pics of the mosfets and the charger IC for a verification.

the adapter voltage is present, around 20 volts, "power adapter connector" image

I marked all the mosfets I found in front and rear of the board, I will check voltage on all of them and report here.

I attached an image of battery connector, can you help me locating the charger IC?

[vpower]

Re: HP Pavillion 15-cw1077nl no power

I could only locate 2 classic mosfets, one on the front side and one on the rear side.
front side:
source(1-2-3) 0.4v
gate (4) 0.3v
drain 0v

rear side
source 0v
gate 0.2v
drain 22v

[mon2]

Re: HP Pavillion 15-cw1077nl no power

The charger IC is the square on marked BQ738H.

The part is a custom marked version with little public information. However we can get what we need from here and comparing to other similar parts from Texas Instruments.

https://www.datasheetcafe.com/bq2473...ge-controller/

With care, meter in dc volts mode, measure the voltage to ground of the VCC pin on the charger IC.

Also interested in the following:

REGN
ACDRV
ACOK

Post each measurement.

[vpower]

Re: HP Pavillion 15-cw1077nl no power

here the measurements:

VCC 21.1v
REGN 6.9V
ACDRV 0.1V/0.2V
ACOK 0V

[mon2]

Re: HP Pavillion 15-cw1077nl no power

So the chip is being powered.

ACDRV is not a good voltage. It should be ~25 volts to enable the DCin mosfets.

ACDRV 0.1V/0.2V
ACOK 0V

Check the voltage of ACDET. This is a voltage that is built by 2 resistors to lower the adapter voltage to a safe voltage for the charger IC. If the voltage on this pin is above ~2v7 then the adapter is deemed to be suitable and connected to power the laptop.

[vpower]

Re: HP Pavillion 15-cw1077nl no power

ACDET is 3.1v

[mon2]

Re: HP Pavillion 15-cw1077nl no power

This is a good value.

Remove all power. Meter in diode mode. Touch your meter probes and you will hear a tone beep.

Now one probe to ACDRV pin, other to nearby black resistor parts. If you hear a tone, stop. This is the 4k resistor in series with the ACDRV pin.

Continue to locate the mosfets as follows.

Meter probe on the other side of this same resistor.

Other probe to pin #4 of any local mosfet. If you hear a tone beep, stop. This is one of your 2*DCin mosfets.

Identify the mosfets and share an updated picture.