Dell Latitude 7390 charging but battery not increasing

[dqtech]

here the link for schematic - https://www.badcaps.net/forum/troubl...-the-bios-chip

board number LA-F312P ....laptop charging but not increasing percentage...charge rate very low on BATMON ....i try use another battery also same result...but when i try this battery and adapter to another laptop (dell latitude 7300) its charging normally and charge rate goes to 19k-20k mW

[mcplslg123]

ACOK/ACIN /HW_ACAVIN_NB status?
Charging ic pin1-2 connectivity to PR917 intact as per rated resistance value?
SDA/SCL communication on pin21/22 checked with DSO?
PQ1202/1213-gate voltage?

[dqtech]

ACOK/ACIN /HW_ACAVIN_NB status?
Charging ic pin1-2 connectivity to PR917 intact as per rated resistance value?
SDA/SCL communication on pin21/22 checked with DSO?
PQ1202/1213-gate voltage?

hi sir...here the update about this laptop...without battery

ACOK = 3v
ACIN = 3.5v
HW_ACAVIN_NB = 3.3v
PQ1202 gate = 18.5v
PQ1213 gate = 1.2v
Charging ic pin1-2 connectivity to PR917 = 1.5ohm



SDA/SCL communication on pin21/22 checked with DSO? = is this need use Oscilloscope?..because i dont have it

[mon2]

Carry on with the debug guide as per mcplslg123.

From your measurements,

PQ1202 gate = 18.5v
PQ1213 gate = 1.2v

From the schematics, review the datasheet for these mosfets. From the datasheets, we know that each is a P-channel mosfet type.

For a P-channel mosfet to turn on, the gate voltage must be lower than the voltage being passed between source / drain pins. PQ1213 should be ON based on the very low gate voltage.

PQ1202, however, has the gate voltage at ~adapter voltage -> the voltage from the drain pins (5-6-7-8) is passing through the internal diode of PQ1202 and onto the source pins (1-2-3) and through the resistor @ PR1207.

From this voltage we know that PQ1201B is OFF since the voltage at the gate pin is so high. That is, when PQ1201B is ON, the gate pin will be pulled to ground through PR1213 and together, PR1213 & PR1207 will build a voltage divider. This process will lower the gate voltage and fully turn on PQ1202.

The voltage divider is not being enabled so this means VBUS1_ECOK is not a logic '1' to enable the mosfet @ PQ1201B (N-channel mosfet).

Confirm the voltage to ground of VBUS1_ECOK.

As a quick test, connect a piece of wire from PR1213 - pin # 2 - this pin is also mating with PQ1201B so double-check this trace. Other side of the wire to ground. We are bypassing the PQ1201B mosfet with this process. This will lower the gate voltage to enable the P-channel mosfet @ PQ1202.

[dqtech]

Carry on with the debug guide as per mcplslg123.

From your measurements,



From the schematics, review the datasheet for these mosfets. From the datasheets, we know that each is a P-channel mosfet type.

For a P-channel mosfet to turn on, the gate voltage must be lower than the voltage being passed between source / drain pins. PQ1213 should be ON based on the very low gate voltage.

PQ1202, however, has the gate voltage at ~adapter voltage -> the voltage from the drain pins (5-6-7-8) is passing through the internal diode of PQ1202 and onto the source pins (1-2-3) and through the resistor @ PR1207.

From this voltage we know that PQ1201B is OFF since the voltage at the gate pin is so high. That is, when PQ1201B is ON, the gate pin will be pulled to ground through PR1213 and together, PR1213 & PR1207 will build a voltage divider. This process will lower the gate voltage and fully turn on PQ1202.

The voltage divider is not being enabled so this means VBUS1_ECOK is not a logic '1' to enable the mosfet @ PQ1201B (N-channel mosfet).

Confirm the voltage to ground of VBUS1_ECOK.

As a quick test, connect a piece of wire from PR1213 - pin # 2 - this pin is also mating with PQ1201B so double-check this trace. Other side of the wire to ground. We are bypassing the PQ1201B mosfet with this process. This will lower the gate voltage to enable the P-channel mosfet @ PQ1202.

VBUS1_ECOK = 0v

PR1213 pin 2 jumper to ground ( i took from PQ1201 pin 1) = gate on PQ1202 become 1.7v sir and VBUS1_ECOK still remain 0v

[mon2]

When you did the PR1213 pin 2 jumper bypass, does the charge current change / increase at all?

[dqtech]

When you did the PR1213 pin 2 jumper bypass, does the charge current change / increase at all?

not increase sir....with and without battery current still around 0.600ma

[mon2]

Can you confirm the voltage to ground of the following?

PJP102 ; +3.3V_ALWP
PJP103 ; +5V_ALWP

3.3V_ALW2 ; PU100 pin 17 LDO

The EC is required to enable the VBUS1_ECOK signal but EC is powered by the above rails.

Charging ic pin1-2 connectivity to PR917 = 1.5ohm

Meter in resistance mode. Touch your meter probes together. What is the exact resistance in ohms?

Next, place one meter prove directly on pin #1 of the charger IC @ PU901. Other meter probe directly on pin # 2. What is the exact resistance?

It should be ~2 ohms. Total resistance = PR937 + PR938 + PR917 = 1 + 1 + 0.005 (too small to measure = 5 milliohms) = 2 ohms. This total resistance is important.

[dqtech]

Can you confirm the voltage to ground of the following?

PJP102 ; +3.3V_ALWP
PJP103 ; +5V_ALWP

3.3V_ALW2 ; PU100 pin 17 LDO

The EC is required to enable the VBUS1_ECOK signal but EC is powered by the above rails.




Meter in resistance mode. Touch your meter probes together. What is the exact resistance in ohms?

Next, place one meter prove directly on pin #1 of the charger IC @ PU901. Other meter probe directly on pin # 2. What is the exact resistance?

It should be ~2 ohms. Total resistance = PR937 + PR938 + PR917 = 1 + 1 + 0.005 (too small to measure = 5 milliohms) = 2 ohms. This total resistance is important.

here sir..
PJP102 = 3.4v
PJP103 = 5.2v
PU100 pin 17 LDO = 3.3v

Meter in resistance mode. Touch your meter probes together. What is the exact resistance in ohms? = 0.000ohm
Next, place one meter prove directly on pin #1 of the charger IC @ PU901. Other meter probe directly on pin # 2. What is the exact resistance? = 2.7ohm

[mon2]

Measure each of the resistors in this path individually.

Test PR937 (across the tips) and then PR938. Can you confirm that each is very close to 1R ohms each?

[dqtech]

here sir mon2

PR937 = 1.2 ohm
PR938 = 1.0 ohm

[mon2]

Ok. Now measure the last resistor which is the current sense resistor. This should be ~0Rohms since the schematics show as 5 milliohms.

[dqtech]

Ok. Now measure the last resistor which is the current sense resistor. This should be ~0Rohms since the schematics show as 5 milliohms.

current sense resistor is PR901 right?... if so its 000.0 ohm sir

[mon2]

Repeat the resistance between pins 1&2 of the charger ic.

This should be 2R2 ohms not 2R7 as posted earlier.

If 2R7 ohms then one of the traces in this loop is defective. You will have to test each segment of the circuit to locate which trace is weak.