Dell Latitude 7390 _DAZ20 LA-F312P 1.0 - all power rails up except VCC_CORE and VCC_GT

[NADJIB]

Hello,
I need help please

I have Dell Latitude 7390, LA-F312P 1.0


- power LED turns on a few one second or two withe power supply or battery
- the power supply indicate current 0.16 A While laptop is powered
I checked:

While laptop is powered from battery/barrel plug AND power LED is on, all voltage rails show up, except +VCC_CORE and +VCC_GT.


* COIL
PL612
- Output resistance to ground is 14.7 ohm.
PL613 AND PL610
- Output resistance to ground is 9.8 ohm.

[mon2]

These are good readings. As long as the actual DCin connector is not missing this required signal connection, the power adapter details should be available to the EC. Confirm the DCin connector is in good shape / check the continuity of this same pin to the DCin connector using DIODE mode. Will tone beep if the connection is ok. The power adapter will use this PS_ID pull-up voltage to power a security devices implanted inside its enclosure.

Check the voltage to ground on the following mosfets:

PQ9 ; check source (1-2-3); gate (4); drain (5-6-7-8) - each to ground voltage
PQ4 ; (same as above)

Check PU901 (charger IC),
pin # 24 (ACOK) ; this line should be a logic high if the power adapter is deemed to be ok to power this board

PBAT_CHARGER_SMBDAT ; to confirm the required SMBUS lines are not stuck due to an ESD event or similar
PBAT_CHARGER_SMBCLK

[mon2]

It is a Dell so the adapter details are important. Are you using the official Dell adapter? Rated for this model of laptop?

Dell will use a single wire communication to extract the adapter identity and this communication is often broken to raise the same observation.

check the PS_ID line voltage from the power adapter.

Measure the voltage to ground of:

PS_ID
NB_PSID

post the measurements. The communication line is powered through the parasitic pull-up voltage +3.3V_ALW through PR4 resistor. If the mosfet @ PQ2 is damaged, the single wire ID chip inside the true Dell adapters cannot be powered to share the details of the power adapter. This is the Maxim / Dallas Semiconductor single-wire communication protocol.

[NADJIB]

It is a Dell so the adapter details are important. Are you using the official Dell adapter? Rated for this model of laptop?

Dell will use a single wire communication to extract the adapter identity and this communication is often broken to raise the same observation.

check the PS_ID line voltage from the power adapter.

Measure the voltage to ground of:

PS_ID
NB_PSID

post the measurements. The communication line is powered through the parasitic pull-up voltage +3.3V_ALW through PR4 resistor. If the mosfet @ PQ2 is damaged, the single wire ID chip inside the true Dell adapters cannot be powered to share the details of the power adapter. This is the Maxim / Dallas Semiconductor single-wire communication protocol.

Thank you for your interaction,
yes i using the official Dell adapter
PS_ID = 3.29V
NB_PSID = 3.29V

all the best for you

[mon2]

These are good readings. As long as the actual DCin connector is not missing this required signal connection, the power adapter details should be available to the EC. Confirm the DCin connector is in good shape / check the continuity of this same pin to the DCin connector using DIODE mode. Will tone beep if the connection is ok. The power adapter will use this PS_ID pull-up voltage to power a security devices implanted inside its enclosure.

Check the voltage to ground on the following mosfets:

PQ9 ; check source (1-2-3); gate (4); drain (5-6-7-8) - each to ground voltage
PQ4 ; (same as above)

Check PU901 (charger IC),
pin # 24 (ACOK) ; this line should be a logic high if the power adapter is deemed to be ok to power this board

PBAT_CHARGER_SMBDAT ; to confirm the required SMBUS lines are not stuck due to an ESD event or similar
PBAT_CHARGER_SMBCLK

[NADJIB]

These are good readings. As long as the actual DCin connector is not missing this required signal connection, the power adapter details should be available to the EC. Confirm the DCin connector is in good shape / check the continuity of this same pin to the DCin connector using DIODE mode. Will tone beep if the connection is ok. The power adapter will use this PS_ID pull-up voltage to power a security devices implanted inside its enclosure.

Check the voltage to ground on the following mosfets:

PQ9 ; check source (1-2-3); gate (4); drain (5-6-7-8) - each to ground voltage
PQ4 ; (same as above)

Check PU901 (charger IC),
pin # 24 (ACOK) ; this line should be a logic high if the power adapter is deemed to be ok to power this board

PBAT_CHARGER_SMBDAT ; to confirm the required SMBUS lines are not stuck due to an ESD event or similar
PBAT_CHARGER_SMBCLK

hello ,