Acer Predator GH51M LA-K862P NO POWER

[mon2]

1) Confirm that pin # 28 (VCC) on the charger IC (PUB1) is receiving the adapter voltage. Otherwise the charger IC is not being powered.

2) You must also have a voltage present on ACDET pin # 6 on the charger IC since this voltage is based on a resistor based voltage divider where the power adapter is the power feed. Confirm it. Otherwise you have defective resistors or a broken PCB trace / bad soldering from +19V_VIN to ACDET. Suggest to remove all power -> meter in resistance mode. Check the resistance from direct pin #6 on the charger IC (ACDET) to +19V_VIN that is the raw voltage from the power adapter. This measurement should be ~422K ohms.

3) Update - confirm the voltage to ground of ADAPDET which is from the power adapter. This voltage should be 0 volts - that is, when the power adapter is mated to this logic board, this ADAPDET line should pull the GATE voltage of PQB17 (2N7002) to be low or 0 volts. This in turn will turn OFF PQB17 so that the ACDET pin on the charger IC can receive a valid threshold voltage from the power adapter. If the ADAPDET line is NOT pulling the gate pin to ground then PQB17 will be ON (due to the voltage divider resistors on the same gate pin) and then ACDET will be pulled to 0 volts. PQB17 is acting like a switch to ground for ACDET. Confirm this area.

[madjid911]

my voltage divider with PB11 and PRB13 on ACDET is not good I do not have 0V6, I HAVE 0V, however my resistance is good and I do have 19V arriving on PRB11 (prb11 400K and prb13 68k are good)

[mon2]

Appears to be a broken trace between the charger IC's ACDET pin and the 19v rail. Confirm it by removing all power. Meter in DIODE mode. Short your meter probes and the meter should tone beep. Then connect one meter probe onto the ACDET pin directly on the charger IC. For this simple test, the choice of the meter probe color does not matter. The other meter probe to the PRB11 resistor. Check both sides of PRB11. One side must tone beep. Confirm this important detail.

[madjid911]

Appears to be a broken trace between the charger IC's ACDET pin and the 19v rail. Confirm it by removing all power. Meter in DIODE mode. Short your meter probes and the meter should tone beep. Then connect one meter probe onto the ACDET pin directly on the charger IC. For this simple test, the choice of the meter probe color does not matter. The other meter probe to the PRB11 resistor. Check both sides of PRB11. One side must tone beep. Confirm this important detail.

yes I have continuity

[mon2]

Good. Then you must have voltage as well unless PQB17 is shunting this voltage to ground. Locate PQB17 which should be nearby. We are interested in the voltage to ground of each pin on this part. Specifically interested in the GATE voltage. This will be small 3 legged black color part. In summary, if the GATE voltage is high enough, then PQB17 is ON and if it is ON, this ACDET voltage will be 0 volts.

[madjid911]

1) Confirm that pin # 28 (VCC) on the charger IC (PUB1) is receiving the adapter voltage. Otherwise the charger IC is not being powered.

2) You must also have a voltage present on ACDET pin # 6 on the charger IC since this voltage is based on a resistor based voltage divider where the power adapter is the power feed. Confirm it. Otherwise you have defective resistors or a broken PCB trace / bad soldering from +19V_VIN to ACDET. Suggest to remove all power -> meter in resistance mode. Check the resistance from direct pin #6 on the charger IC (ACDET) to +19V_VIN that is the raw voltage from the power adapter. This measurement should be ~422K ohms.

3) Update - confirm the voltage to ground of ADAPDET which is from the power adapter. This voltage should be 0 volts - that is, when the power adapter is mated to this logic board, this ADAPDET line should pull the GATE voltage of PQB17 (2N7002) to be low or 0 volts. This in turn will turn OFF PQB17 so that the ACDET pin on the charger IC can receive a valid threshold voltage from the power adapter. If the ADAPDET line is NOT pulling the gate pin to ground then PQB17 will be ON (due to the voltage divider resistors on the same gate pin) and then ACDET will be pulled to 0 volts. PQB17 is acting like a switch to ground for ACDET. Confirm this area.

1) Yes 19V5 on PRB12 but PDB1 pin 2 : 0V, PIN 1 3 : 19V5
2) BQ pin 6 (ACDET) : 6,37kohms, I unsoldered PRB11 and PRB13 to measure them, they are good.
3) PQB17 pin 1 : 0V, pin 2 :5V25

[madjid911]

Good. Then you must have voltage as well unless PQB17 is shunting this voltage to ground. Locate PQB17 which should be nearby. We are interested in the voltage to ground of each pin on this part. Specifically interested in the GATE voltage. This will be small 3 legged black color part. In summary, if the GATE voltage is high enough, then PQB17 is ON and if it is ON, this ACDET voltage will be 0 volts.

I understand better why I have zero on ACDET then, because the PQB17 gate has too high a voltage, what is this due to? I tried several chargers, it's the same.

[mon2]

Good. This means that the GROUND or adapter inserted pin is not working on the DCin power connector = pin # 4. Review this connector. For now, carefully take a piece of wire and connect one side to ground and the other side to the GATE pin of PQB17 while the power adapter is connected. This procedure will cause PQB17 to turn OFF and the ACDET pin should then be as expected and should be ~2v or higher. Post the results. Need to run out to drop off something in the crazy -17 degree outside temp. BBL.

[madjid911]

Good. This means that the GROUND or adapter inserted pin is not working on the DCin power connector = pin # 4. Review this connector. For now, carefully take a piece of wire and connect one side to ground and the other side to the GATE pin of PQB17 while the power adapter is connected. This procedure will cause PQB17 to turn OFF and the ACDET pin should then be as expected and should be ~2v or higher. Post the results. Need to run out to drop off something in the crazy -17 degree outside temp. BBL.

Ok thanks, I put the gate of PQB17 pin 2 to the gnd. My voltage divider works: 0V4 on ACDET but I still don't have my mosfets closed, I will put the BQ24701 chip back because I had put BQ24708S. I think I'll have to order a new charging connector it looks bad

[madjid911]

Good. This means that the GROUND or adapter inserted pin is not working on the DCin power connector = pin # 4. Review this connector. For now, carefully take a piece of wire and connect one side to ground and the other side to the GATE pin of PQB17 while the power adapter is connected. This procedure will cause PQB17 to turn OFF and the ACDET pin should then be as expected and should be ~2v or higher. Post the results. Need to run out to drop off something in the crazy -17 degree outside temp. BBL.

I put BQ24701 back, and I finally have my mosfets closed, the whole motherboard is powered by 20v now, the pc starts up perfectly. Is it really necessary to change the charging connector or can I leave PQB17 gate shunted to GND Please ? You are really very strong, thank you very much.

[mon2]

Did I miss the fireworks ? Excellent !! Good job. You can leave the PQB17 shunted to ground OR you can remove PQB17. Either way, the ACDET voltage needs to be in a normal range and above the threshold to properly detect the power adapter. Yes, do believe that the DC power jack was the root cause and then the charger IC being replaced. As Louis would call it - down the rabbit hole to h*ll.

Well done.

[madjid911]

Did I miss the fireworks ? Excellent !! Good job. You can leave the PQB17 shunted to ground OR you can remove PQB17. Either way, the ACDET voltage needs to be in a normal range and above the threshold to properly detect the power adapter. Yes, do believe that the DC power jack was the root cause and then the charger IC being replaced. As Louis would call it - down the rabbit hole to h*ll.

Well done.

I had to remove PQB17 because with the PQB17 grounded, the PC faulted the fan blowing very much, since I removed it everything works perfectly, again a big thank you I will not fail to make a donation for the forum

[grayfox112]

good morning, sorry to reopen the discussion, I have the same problem, reading it seems to me that the problem is the component BQ24701, correct? I have to replace it and remove the component PQB17??
Thank you