HP 15-cb028nl (dag75ambad0 rev. d) no charge battery

[zaurus81]

Hi all, I have a HP 15-cb028nl (dag75ambad0 rev. d) that turns on but does not charge the battery. The laptop arrived with the super I/O (ITE IT8987E BXA) burned. After replacing the EC, it turns on but does not charge the battery. Below are the voltages on the pins of the bq24738h, with and without the battery inserted:

WITHOUT BATTERY	WITH BATTERY
PIN1 (ACN)= 19.76 V	PIN1 (ACN)= 19.76 V
PIN2 (ACP)= 19.76 V	PIN2 (ACP)= 19.76 V
PIN3 (CMSRC)= 19.74 V	PIN3 (CMSRC)= 19.74 V
PIN4 (ACDRV)= 25.66 V	PIN4 (ACDRV)= 25.66 V
PIN5 (ACPRES)= 3.00 V	PIN5 (ACPRES)= 3.00 V
PIN6 (ACDET)= 2.68 V	PIN6 (ACDET)= 2.68 V
PIN7 (IOUT)= 0.00 V	PIN7 (IOUT)= 0.00 V
PIN8 (SDA)= 3.22 V	PIN8 (SDA)= 3.09 V
PIN9 (SCL)= 3.22 V	PIN9 (SCL)= 3.09 V
PIN10 (ILIM)= 0.99 V	PIN10 (ILIM)= 0.99 V
PIN11 (BATDRV)= 2.96 V	PIN11 (BATDRV)= 1.07 V
PIN12 (SRN)= 2.94 V	PIN12 (SRN)= 1.05 V
PIN13 (SRP)= 2.94 V	PIN13 (SRP)= 1.05 V
PIN14 (GND)= GND	PIN14 (GND)= GND
PIN15 (LODRV)= 0.00 V	PIN15 (LODRV)= 0.00 V
PIN16 (REGN)= 6.03 V	PIN16 (REGN)= 6.03 V
PIN17 (BTST)= 5.87 V	PIN17 (BTST)= 5.87 V
PIN18 (HIDRV)= 2.94 V	PIN18 (HIDRV)= 1.05 V
PIN19 (PHASE)= 2.94 V	PIN19 (PHASE)= 1.05 V
PIN20 (VCC)= 19.16 V	PIN20 (VCC)= 19.16 V

I removed the high and low mosfets to test them outside the circuit and they seem ok. analyzing the board with the thermal camera there are no hot spots, in fact even with the bench power supply the absorption with the board in standby (s5) is 7 mA.
BQ gone??
thanks in advance to anyone who answers me

[mon2]

PIN3 (CMSRC)= 19.74 V

CMSRC is between the 2 x DCin mosfets in the main power path. You should not have a voltage here when using only the battery. Confirm this measurement again.

If you do, review the DCin mosfets for leakage.

Remove all power. Meter in resistance mode.

Measure:

source / drain
source / gate
gate / drain

Post each measurement. Test both DCin mosfets. Suspecting that at least the 2nd one is defective.

Update - you have both, adapter & battery attached. Continue to test the mosfets as above.

[zaurus81]

CMSRC is between the 2 x DCin mosfets in the main power path. You should not have a voltage here when using only the battery. Confirm this measurement again.

If you do, review the DCin mosfets for leakage.

Remove all power. Meter in resistance mode.

Measure:

source / drain
source / gate
gate / drain

Post each measurement. Test both DCin mosfets. Suspecting that at least the 2nd one is defective.

Update - you have both, adapter & battery attached. Continue to test the mosfets as above.

hi mon2, sorry I expressed myself badly in a hurry, the values with the battery inserted were measured with the charging jack inserted, that's why I have 19.77 v

DCin mosfets are PQ1015 PQ1003 PQ1002?? see boardview - https://www.badcaps.net/forum/troubl...75ambad0-rev-d

[mon2]

Yes, I agree with your findings.

My search was as follows:

(boardview file only)

Searched for REGN -> found the charger IC -> found the ACDRV pin -> found the ACDRV series resistor -> other side of this resistor mates to the DCin mosfet gate pin # 4.

[zaurus81]

Yes, I agree with your findings.

My search was as follows:

(boardview file only)

Searched for REGN -> found the charger IC -> found the ACDRV pin -> found the ACDRV series resistor -> other side of this resistor mates to the DCin mosfet gate pin # 4.

DCin mosfets tested:

first mosfet (PQ1003)
source / drain 2.6M OHM
source / gate OL
gate / drain OL

second mosfet (PQ1002)
source / drain 4.3 M OHM
source / gate 3,4 M OHM
gate / drain 6,3 M OHM

[mon2]

Mosfets look ok to me. Suggest to test with another known good battery. Amazon?

The low voltage with battery on SRN / SRP are of concern. These pins should reflect the battery charge voltage. That is, the high side and low side mosfets linked to the battery connector pins should be switching to dial up the ideal charge voltage to charge the pack. That is, unless the battery is locked.

You can also test the nearby mosfets used by the battery in the same was as above to confirm they are not leaking.

[mcplslg123]

SRN/SRP voltage perhaps indicate a dead battery.

[zaurus81]

Mosfets look ok to me. Suggest to test with another known good battery. Amazon?

The low voltage with battery on SRN / SRP are of concern. These pins should reflect the battery charge voltage. That is, the high side and low side mosfets linked to the battery connector pins should be switching to dial up the ideal charge voltage to charge the pack. That is, unless the battery is locked.

You can also test the nearby mosfets used by the battery in the same was as above to confirm they are not leaking.

good morning(evening) mon2, so from what you're telling me you're ruling out the presence of a damaged bq chip??

[zaurus81]

SRN/SRP voltage perhaps indicate a dead battery.

hi mcplslg123, SRP/SRN without battery is 2.94V. is this normal due to no battery? or is the bq chip not switching the 2 mosfets?

[Sametbey]

maybe it can help you.

[Sephir0th]

Bad battery need to be ruled out.

[zaurus81]

maybe it can help you.

thank you

[maniche]

2,96 without battery look normal for me, but I don'tt see the voltage of battery, which mean the battery is dry, try to charge it with a power powersuplay ,if battery is to low the laptop will not charge it