Acer nitro 5 N20C2 No charge

[madjid911]

hello I have an acer nitro 5 model N20C2 (motherboard FH51M LA-J871P rev 1B) which does not charge, it turns on perfectly but when I plug in the battery, we see the charging indicator and the charged battery logo but it turns off a few seconds later, and there is no way to turn it back on, you must then disconnect the battery and the charger. If I turn it on without the battery it works fine.

I changed BQ24781 but the result is the same, I put after BQ24800 the same, I then checked all the resistors and mosfets, everything is ok, I bought a new new battery but the result is the same PC does not turn on with battery connected

here are my measurements :


PRB7 AND PRB10 = 4 KOHMS
PRB4 = 4,7 OHMS
PRB1 = 1 MOHMS
PRB31 = 10 KOHMS
PRB27 = 10 KOHMS PIN1 = 6V, pin 2 = 3V3, +6V_CHG_REGN = 6V.
PRB32 = 11,8KOHMS

BQ24 :
ACDET 2V6, REGN 6V, VCC 20v, ACOK 3V3

PRB5 : 4KOHMS
PRB6 : 10OHMS
PR212 : 100KOHMS
PR202 : 200KOHMS
PR203 : 1KOHMS
PR207 : 100OHMS
PR205: 100OHMS
PRB14 PRB17: OHMS
mosfet PQB5 PQB2 AND BPB6 are good
PCB23 AND PCB22 are good 16V45


PJP201 with battery :
Broche n° 3 EC_SMB_DA1 : 3V24
Broche n° 4 EC_SMB_SK1 : 3V24
Broche n° 5 BATT_TS : 0V155
Broche n° 6 BATT_B/I : 0V
Briche n° 7 AND 8 : 16V44

PQ201 :
pin1 : 0V
pin2 : 2V9
pin 3 : 0V


I am not an expert in electrical diagrams if anyone can help me on this, is PQ201 defective? THANKS

[madjid911]

PQ201 pin 1 is connected to pin 3 to ground is this normal?

[madjid911]

PQ201 pin 1 is connected to pin 3 to ground is this normal?

no it was just residual current, pin 1 and pin 3 is not connected

[mon2]

<< found the schematics - not required >>

If possible, share the voltage on each charger pin with adapter and battery. Post in a table format.

Measure the voltage to ground on the battery connector for:

Pin # 3 EC_SMB_DA1
Pin # 4 EC_SMB_SK1

The above 2 lines are used to communicate with the BMS board that is inside of each battery pack to extract serial #, mfr codes, # of charge cycles, etc. Are these details visible inside of Windows? If yes, these lines are ok.

[madjid911]

PJP101 (charging connector adaptater) :
pin 1 : 19V89
pin 4 : 0V (but pqb11 pin 1 acdet : 2V6)

PRB17 and PRB14 : 3V2

PJP202 (charging port battery) :
Broche n° 3 EC_SMB_DA1 : 3V24
Broche n° 4 EC_SMB_SK1 : 3V24
Broche n° 5 BATT_TS : 0V155
Broche n° 6 BATT_B/I : 0V
Briche n° 7 AND 8 : 16V44

I can't see the battery information because the pc turns off after a few seconds if I connect the battery

[mon2]

PJP101 (charging connector adaptater) :
pin 1 : 19V89
pin 4 : 0V (but pqb11 pin 1 acdet : 2V6)

With pin 4 = 0 volts, then means that PQB11 GATE pin is also @ 0 volts. If the GATE pin of PQB11 is at 0 volts, then this mosfet 2N7002 will remain OFF. If the mosfet is OFF, then the only available power source at pin # 1 will be from the resistor based voltage divider built by PRB11 & PRB13 (the 0 ohm resistors do not count in the equation). These other resistors create a lower and acceptable voltage of 2v6 for the ACDET function.

If the power adapter is MISSING, then the 0 volts supplied by the adapter (actually a short to ground) will also disappear. Then the voltage created by the 2 resistors @ PRB35 & PRB36 will create a high enough voltage from the power adapter that PQB11 will ENABLE. If PQB11 mosfet is enabled, then pin # 1 will pull down the ACDET voltage to ground. That is, the SOURCE & DRAIN pins will short together to lower the ACDET voltage to 0 volts. This will cause the charger IC to detect that the power adapter is no longer present.

The EC_SMB lines are ok and not shorted.

[SMDFlea]

hello I have an acer nitro 5 model N20C2 (motherboard FH51M LA-J871P rev 1B) which does not charge

Post a LINK to the schematic

Reminder: rules and organization of this section ->
https://www.badcaps.net/forum/troubl...f-this-section
If you request/offer BIOS/schematics/boardviews, please post in the appropriate subsection, and you can link to it in the troubleshooting topic.

[madjid911]

With pin 4 = 0 volts, then means that PQB11 GATE pin is also @ 0 volts. If the GATE pin of PQB11 is at 0 volts, then this mosfet 2N7002 will remain OFF. If the mosfet is OFF, then the only available power source at pin # 1 will be from the resistor based voltage divider built by PRB11 & PRB13 (the 0 ohm resistors do not count in the equation). These other resistors create a lower and acceptable voltage of 2v6 for the ACDET function.

If the power adapter is MISSING, then the 0 volts supplied by the adapter (actually a short to ground) will also disappear. Then the voltage created by the 2 resistors @ PRB35 & PRB36 will create a high enough voltage from the power adapter that PQB11 will ENABLE. If PQB11 mosfet is enabled, then pin # 1 will pull down the ACDET voltage to ground. That is, the SOURCE & DRAIN pins will short together to lower the ACDET voltage to 0 volts. This will cause the charger IC to detect that the power adapter is no longer present.

The EC_SMB lines are ok and not shorted.

Thank you for this explanation, but where could the problem come from?

[mon2]

As per the above charger sticky by piernov, often the fault is with the 2nd DCin mosfet = PQB4 on your board.

Remove all power. Meter in resistance mode. Measure the resistance across the mosfet pins as follows:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement. Often, this mosfet will be leaky and allows for the logic board to power up but does not behave with the existence of a battery and the external power adapter.

[madjid911]

As per the above charger sticky by piernov, often the fault is with the 2nd DCin mosfet = PQB4 on your board.

Remove all power. Meter in resistance mode. Measure the resistance across the mosfet pins as follows:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement. Often, this mosfet will be leaky and allows for the logic board to power up but does not behave with the existence of a battery and the external power adapter.

source (1-2-3) et drain (5-6-7-8) : 3,71 MOHMS
source (1-2-3) et grille (4) : (red on source) 8,12 MOHMS, and (red on grille) OL
grille (4) et drain (5-6-7-8) : (red on drain) 12,2 MOHMS, and (red on grille) : OL

I just noticed that the PQB3 mosfet was no longer closed when I plug in the battery, it no longer delivers 20v, I have 16V44 at the output of the PQB4 which corresponds to the battery voltage

[madjid911]

I again changed the bq24 charging ic with an original BQ24781, but the result is the same, why does bq24 refuse to send the signal to close PQB3 when I connect the battery?

[mon2]

The mosfet readings are good and the mosfet is not shorted. High resistance readings = not a leaky mosfet.

1) Share a close up pic of the reworked battery charger IC for a review.

2) The charger IC will enable the DCin power path provided a number of conditions are met. Respectively, it is possible that the DCin power path is enabled but quickly shutdown due to an excessive current draw event. Then this shutdown event will be missed by the time the signals are monitored.

3) Can you link the exact schematic you are using? I may be out of sync with my schematic and want to be on the same page.

[madjid911]

The mosfet readings are good and the mosfet is not shorted. High resistance readings = not a leaky mosfet.

1) Share a close up pic of the reworked battery charger IC for a review.

2) The charger IC will enable the DCin power path provided a number of conditions are met. Respectively, it is possible that the DCin power path is enabled but quickly shutdown due to an excessive current draw event. Then this shutdown event will be missed by the time the signals are monitored.

3) Can you link the exact schematic you are using? I may be out of sync with my schematic and want to be on the same page.

I use the diagram that I attached on the first page (LA-J871P).
It seems as you say that this resembles excessive consumption when the battery is connected, so the bq24 goes into safety mode and no longer gives the signal, but where can this consumption come from?

for welds I always check under the microscope that everything is well connected

[mon2]

Soldering looks very clean to me. We have the same schematics.

The shutdown can occur if there truly is an excessive current draw on any of the power regulators or from a missing part / bad solder joint linked to the current sensing circuit.

Remove all power. Meter in the lowest resistance scale. Measure directly on the charger IC - the resistance between pins 19 & 20. One meter probe on pin # 19; other on pin # 20. You are measuring the current sense path resistance and need to compare this measurement against the schematic. If it is different, the fault is here. Last year, we invested 3 weeks in another case in the forum and the fault was here.

You are checking the SRP / SRN path resistance which is used by the battery charge circuit.

[madjid911]

Soldering looks very clean to me. We have the same schematics.

The shutdown can occur if there truly is an excessive current draw on any of the power regulators or from a missing part / bad solder joint linked to the current sensing circuit.

Remove all power. Meter in the lowest resistance scale. Measure directly on the charger IC - the resistance between pins 19 & 20. One meter probe on pin # 19; other on pin # 20. You are measuring the current sense path resistance and need to compare this measurement against the schematic. If it is different, the fault is here. Last year, we invested 3 weeks in another case in the forum and the fault was here.

You are checking the SRP / SRN path resistance which is used by the battery charge circuit.

broches 19 et 20 : 20,2OHMS (résistance PRB26 and PRB24 are good 10HOMS)
résistance PRB19 is good 0HOM
on the other hand I don't have the PCB24 component, is this normal or is it a missing capacitor?

[madjid911]

Originally this laptop came with a short circuit on the PCZ70 capacitor, two weeks later it was short circuited again so I had to change it twice, maybe the overconsumption comes from there?

The GPU has very low resistance, is it normal to have only 0.3 ohms on the GPU? I disconnected the coils but the result remains the same when I connect the battery the mosfets are no longer closed

[mcplslg123]

Resistance to GND as low as 0.1 Ohms is very very likely fine on gaming laptop's GPU.

[madjid911]

Resistance to GND as low as 0.1 Ohms is very very likely fine on gaming laptop's GPU.

ok thank you, so I checked everything (resistance, soldering, shorts) I can't find anything, I don't see where the problem is coming from

[mon2]

I do believe we had this same case yesterday.

reference:
Acer nitro 5 bq24781 no acdrv - Badcaps

What is the voltage to ground of ACDET ?

Flux and remove PQB11. Test again.

[madjid911]

I do believe we had this same case yesterday.

reference:
Acer nitro 5 bq24781 no acdrv - Badcaps

What is the voltage to ground of ACDET ?

Flux and remove PQB11. Test again.

ACDET to GND : 177kohms 0V
I removed PQB11 the result is the same when I plug in the battery the mofest no longer sends the 20v
it's not the same subject, mine works perfectly without battery, it's just that once you plug in the battery it goes into safety mode and turns off, there's no way to turn it back on, you have to disconnect the battery