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Asus x453ma not charging
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Re: Asus x453ma not charging
SDA and SCL voltages are normal, but ACOK is only 1.68v
ACOK, SDA and SCL are each open-drain pins. Each of these open-drain pins will have a pull-up to the +3v3 rail. So expecting that the voltage reading should be the same for all 3 of these pins.
Can you trace the circuit to locate the local pull-up for ACOK ? Once it is found, check the other side of this resistor and confirm it is +3v3. There is a chance that the PU resistor is to +1v8 but check for it with your meter.
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Re: Asus x453ma not charging
Originally posted by mon2 View PostWhat are the voltages for SDA & SCL ?
ACOK, SDA and SCL are each open-drain pins. Each of these open-drain pins will have a pull-up to the +3v3 rail. So expecting that the voltage reading should be the same for all 3 of these pins.
Can you trace the circuit to locate the local pull-up for ACOK ? Once it is found, check the other side of this resistor and confirm it is +3v3. There is a chance that the PU resistor is to +1v8 but check for it with your meter.
SDA & SCL = 3.32v more or less both are almost the same.
gosh you're right, why didn't I realize that, should SDA&SCL be normal as well as ACOK should be normal right?
is there a possibility that this IC is faulty?
if ACOK has a problem, does it affect ACDRV?
because there is no problem on the path that ACDRV passes, but the voltage is still 19v
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Re: Asus x453ma not charging
Originally posted by vinit bhandari View PostHello bro
1-check replace battery first (check old battery voltage also sometime battery shows percentage bt there is no voltage in battery)
2-check sda sdl data clock line path resistors
3-check voltage in mosfet (short,or leakage)
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Re: Asus x453ma not charging
Originally posted by kodox View Postthat's normal, so the BQ "see" adapter plugged in then, but what happen when you unplug adapter when the system on S0 state (full-on)?
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Re: Asus x453ma not charging
See attached.
From the boardview files, pin #5 of the charger IC = AC_OK.
This is an open-drain pin so it must use an external resistor to pull-this line to the logic high level for the pin to function correctly.
This external pull-up resistor is PR8812.
1) Meter in DC volts scale (20V max is ok).
2) Red meter probe on the PR8812 (measure the side of this 1M resistor) - is it 3 volts here ?
3) Then check the OTHER side of PR8812 - what is the voltage ?
4) Finally, what is the voltage on the OTHER side of PR8813 (yellow pad) = the voltage that is @ AC_OK pin of the charger IC ?
Post each voltage reading.
Since this is an open-drain pin, the external resistors define the high voltage value. Being that you have 1v62 on AC_OK then yes the charger IC could be bad OR the external resistors are bad.
Update - capacitor PC8823 is also involved with this AC_OK signal circuit.
Remove PC8823 off the logic board if the AC_OK voltage remains low @ 1v62 since we know for sure that this rail should be close to 3V under normal conditions.
With PC8823, what is the AC_OK voltage ?Last edited by mon2; 11-15-2021, 06:12 AM.
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Re: Asus x453ma not charging
Originally posted by mon2 View PostSee attached.
From the boardview files, pin #5 of the charger IC = AC_OK.
This is an open-drain pin so it must use an external resistor to pull-this line to the logic high level for the pin to function correctly.
This external pull-up resistor is PR8812.
1) Meter in DC volts scale (20V max is ok).
2) Red meter probe on the PR8812 (measure the side of this 1M resistor) - is it 3 volts here ?
3) Then check the OTHER side of PR8812 - what is the voltage ?
4) Finally, what is the voltage on the OTHER side of PR8813 (yellow pad) = the voltage that is @ AC_OK pin of the charger IC ?
Post each voltage reading.
Since this is an open-drain pin, the external resistors define the high voltage value. Being that you have 1v62 on AC_OK then yes the charger IC could be bad OR the external resistors are bad.
Update - capacitor PC8823 is also involved with this AC_OK signal circuit.
Remove PC8823 off the logic board if the AC_OK voltage remains low @ 1v62 since we know for sure that this rail should be close to 3V under normal conditions.
With PC8823, what is the AC_OK voltage ?
PIN1 = 3.31V
PIN2 = 1.65V
PR8813
PIN1 = 1.65V
PIN2 = 1.64V
I've removed the PC8823 but the voltage on PR8812 & PR8813 remains the same and there is no change brother
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Re: Asus x453ma not charging
Remove the dual mosfet (EM6K1-G) to the right side = PQ8810 (6 lead). Keep a note on the pin #1 of the device to be safe. It is the mosfet that is enabled / disabled by the AC_OK signal.
Measure again the voltage on AC_OK. If still low, remove PR8813 (1K) (to isolate the AC_OK pin from the pull-up @ PR8812.
Next, confirm that PR8812 pin #2 floats to +3v. After this testing, the BQ charger must be the fault as it is pulling down AC_OK rather than allowing it to float (high impedance / HI-Z) when 'high' (aka open-collector state).
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Re: Asus x453ma not charging
Originally posted by mon2 View PostSee attached.
From the boardview files, pin #5 of the charger IC = AC_OK.
This is an open-drain pin so it must use an external resistor to pull-this line to the logic high level for the pin to function correctly.
This external pull-up resistor is PR8812.
1) Meter in DC volts scale (20V max is ok).
2) Red meter probe on the PR8812 (measure the side of this 1M resistor) - is it 3 volts here ?
3) Then check the OTHER side of PR8812 - what is the voltage ?
4) Finally, what is the voltage on the OTHER side of PR8813 (yellow pad) = the voltage that is @ AC_OK pin of the charger IC ?
Post each voltage reading.
Since this is an open-drain pin, the external resistors define the high voltage value. Being that you have 1v62 on AC_OK then yes the charger IC could be bad OR the external resistors are bad.
Update - capacitor PC8823 is also involved with this AC_OK signal circuit.
Remove PC8823 off the logic board if the AC_OK voltage remains low @ 1v62 since we know for sure that this rail should be close to 3V under normal conditions.
With PC8823, what is the AC_OK voltage ?
PR8813 = 1.001Kohm
PR8812 = 0.980 Mohm - 1.000 Mohm (unstable)
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Re: Asus x453ma not charging
Originally posted by mon2 View PostRemove the dual mosfet (EM6K1-G) to the right side = PQ8810 (6 lead). Keep a note on the pin #1 of the device to be safe. It is the mosfet that is enabled / disabled by the AC_OK signal.
Measure again the voltage on AC_OK. If still low, remove PR8813 (1K) (to isolate the AC_OK pin from the pull-up @ PR8812.
Next, confirm that PR8812 pin #2 floats to +3v. After this testing, the BQ charger must be the fault as it is pulling down AC_OK rather than allowing it to float (high impedance / HI-Z) when 'high' (aka open-collector state).
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Re: Asus x453ma not charging
For this case it should be fine. The signal is going to the gate of the mosfet. The mosfet is n-channel so needs a positive voltage to turn on. You are removing the mosfet out of circuit.
This is to confirm if the mosfet or charger ic are pulling down this ac_ok signal line.
https://www.electronics-tutorials.ws...or/tran_7.html
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