Asus tp550ld randomly shutdown

[mon2]

Post each voltage present on the resistors linked to pin 10.

Then remove all power and meter in resistance mode. Check the resistance of the same resistors.

First confirm the resistors and their values.

If you remove the linked 2 resistors, then ILIM will be zero volts. Does the charging stop then ?

Do not lose the resistors.

[khelane]

Originally Posted by mon2

Post each voltage present on the resistors linked to pin 10.

Then remove all power and meter in resistance mode. Check the resistance of the same resistors.

First confirm the resistors and their values.

If you remove the linked 2 resistors, then ILIM will be zero volts. Does the charging stop then ?

Do not lose the resistors.

Both resistors outside the motherboard have been tested and are correct in terms of value.
After removing the resistor, the voltage of pin 10 increases and decreases from 0.8V to 1.5V, but the battery light was on and did not turn off.
I re-installed the resistors and measured the voltage of pin 10 again, this time the voltage was 0.811.
I tested several times and tested with another multimeter, the voltage was 0.811!
The voltage on the resistors was 2.4 volts on the 300k resistor, and the voltage on the 100k resistor was 0.8 volts.

[mon2]

Ground pin 10 of this charge IC. This, according to the datasheet will turn off the charging.

Test to see if it does.

[khelane]

Originally Posted by mon2

Ground pin 10 of this charge IC. This, according to the datasheet will turn off the charging.

Test to see if it does.

Pin 10 is grounded.
The charging light did not turn off

[mon2]

Replace the charger IC and test again.

You will have to protect the nearby smd parts so that they do not fly away.

[khelane]

Originally Posted by mon2

Replace the charger IC and test again.

You will have to protect the nearby smd parts so that they do not fly away.

After the replacement, the result will be announced, but I have to catch the IC
There is no similar IC?

[mon2]

There are many suppliers of this part on Aliexpress:

https://www.aliexpress.com/item/3289...18327746%21sea

We have used this vendor many times with success.

Consider to also purchase replacement mosfets that are linked to this charger IC. They are very inexpensive and will also help in future repairs.

[khelane]

Originally Posted by mon2

There are many suppliers of this part on Aliexpress:

https://www.aliexpress.com/item/3289...18327746%21sea

We have used this vendor many times with success.

Consider to also purchase replacement mosfets that are linked to this charger IC. They are very inexpensive and will also help in future repairs.

I found one from a paper motherboard and installed it
All the voltages are the same as before and the device shows images, but the charging light is on

[mon2]

What does Windows report if the battery is not connected ?

[khelane]

Originally Posted by mon2

what does windows report if the battery is not connected ?

plugged in . 100%charged ,,,,,,WITHOUT BATTERY

[mon2]

If you remove the AC power adapter -> attach the battery -> does the unit power up ok with only the battery ?

[khelane]

Originally Posted by mon2

If you remove the AC power adapter -> attach the battery -> does the unit power up ok with only the battery ?

The battery itself is damaged, but it has 6.8 volts, I connected it and connected the charger, the device turned on, but the battery charge did not go above 6.9.
The charger does not turn on, but if I connect the charger and the battery is connected, the device turns on. When I unplug the charger, the battery indicator light flashes and turns off after a few seconds.

A Note
PQ8803 when the battery is only connected, the input is 6.9 volts and the source is 6.9 volts.
When I connect the charger, the output is 19.5 volts, but the source is 6.9 volts!

[mon2]

PQ8803 when the battery is only connected, the input is 6.9 volts and the source is 6.9 volts.
When I connect the charger, the output is 19.5 volts, but the source is 6.9 volts!

Need more details:

1) PQ8803 = ACFET - what are the markings on this MOSFET ?

2) which is the RBFET on your logic board ? (PQ8804 ?) - markings on mosfet?

3) which is the battery FET on your logic board ? (PQ8805 ?) - markings on mosfet ?

With the power removed -> meter in resistance mode -> each mosfet should be reviewed to confirm they are not damaged.

You have listed the resistance values for the above mosfets.

Are the markings the same on PQ8803 and PQ8804 ? The G-S resistance is very different on PQ8804 vs. PQ8803.

[khelane]

Originally Posted by mon2

Need more details:

1) PQ8803 = ACFET - what are the markings on this MOSFET ?

2) which is the RBFET on your logic board ? (PQ8804 ?) - markings on mosfet?

3) which is the battery FET on your logic board ? (PQ8805 ?) - markings on mosfet ?

With the power removed -> meter in resistance mode -> each mosfet should be reviewed to confirm they are not damaged.

You have listed the resistance values for the above mosfets.

Are the markings the same on PQ8803 and PQ8804 ? The G-S resistance is very different on PQ8804 vs. PQ8803.

1:PQ8803 --------M3024M mosfet
2:PQ8804 AND PQ8805 ----- M3002M mosfet

PQ8803 linked source to battery conector
for resistance test 3 time i try

[mon2]

1) mosfet datasheets are attached.

PQ8803 when the battery is only connected, the input is 6.9 volts and the source is 6.9 volts.
When I connect the charger, the output is 19.5 volts, but the source is 6.9 volts!

So PQ8803 = battery FET.

When the power adapter is attached, the charger IC should turn OFF the n-channel mosfet (PQ8803) by lowering the gate voltage on pin # 4.

Confirm it.

When the power adapter is removed, the charger IC should boost the gate voltage (pin 4) to be about 6 volts higher than the source voltage (1-2-3).

Confirm it.

2) When the adapter and battery are connected -> the high side mosfet linked to the battery and charging IC should enable. A concern is that you said the battery is defective. In which way ? If the BMS (battery management system) board is not present / defective or not compatible with this logic board then there is no point to use this battery. This can stop the charging mosfets from working. It all depends on the coding logic used by the vendor.

3) On this topic, confirm that the SMBUS lines actually reach the battery connector. Remove all power -> measure the resistance from the charging IC pins (SDA & SCL) and be sure that they reach the battery connector. With poor coding, the vendor may just be reading '1' logic levels from the pull-ups on the same lines and assuming the battery to be 100%.

You can try to GROUND the SDA line but not sure if it will halt other required communication. This is a safe idea since the SMBUS / I2C lines are open-drain. There is a logic low but never a logic high - the high is always with the pull-up resistors. By design, anyone can pull the line LOW without harm.

The idea is to power up with SDA grounded (on the charging IC) to force the charging IC to see '0'. The host will be communicating with the charging IC to extract out values but curious on the results if you try it. The charging IC also uses the same lines to extract out battery stats.

PS: Have to tend to my dying lawn and fix my sprinkler system - will check back later on your updates.

[khelane]

Originally Posted by mon2

1) mosfet datasheets are attached.



So PQ8803 = battery FET.

When the power adapter is attached, the charger IC should turn OFF the n-channel mosfet (PQ8803) by lowering the gate voltage on pin # 4.

Confirm it.

When the power adapter is removed, the charger IC should boost the gate voltage (pin 4) to be about 6 volts higher than the source voltage (1-2-3).

Confirm it.

.

i'm so sorry

When the adapter is only connected:
PQ8803
Pin 1-2-3 ===== 11.54V
Pin 4 ============ 11.50
Pin 5-6-7-8 ===== 19.5
=============================
When the battery is only connected:
Pin 1-2-3 ====== 7.23 volts
Pin 4 ======== 13.41 volts
Pin 5 6 7 8 ======== 7.24V
=================================
When the battery is connected and the charger
Pin 1-2-3 ======= 8.4V
Pin 4 =========== 13.41 When the charger is connected, the voltage reaches 8.2 volts
Pin 5-6-7-8======= 19.5V
=================================
I will do the rest of the tests tomorrow

[mon2]

These are good voltages for the battery mosfet.

The charger IC is turning ON the battery mosfet when the external power adapter is removed.

The charger IC is turning OFF the battery mosfet when the external power adapter is attached.

I think you should try a known good battery.

[khelane]

Originally Posted by mon2

1) mosfet datasheets are attached.



So PQ8803 = battery FET.

When the power adapter is attached, the charger IC should turn OFF the n-channel mosfet (PQ8803) by lowering the gate voltage on pin # 4.

Confirm it.

When the power adapter is removed, the charger IC should boost the gate voltage (pin 4) to be about 6 volts higher than the source voltage (1-2-3).

Confirm it.

2) When the adapter and battery are connected -> the high side mosfet linked to the battery and charging IC should enable. A concern is that you said the battery is defective. In which way ? If the BMS (battery management system) board is not present / defective or not compatible with this logic board then there is no point to use this battery. This can stop the charging mosfets from working. It all depends on the coding logic used by the vendor.

3) On this topic, confirm that the SMBUS lines actually reach the battery connector. Remove all power -> measure the resistance from the charging IC pins (SDA & SCL) and be sure that they reach the battery connector. With poor coding, the vendor may just be reading '1' logic levels from the pull-ups on the same lines and assuming the battery to be 100%.

You can try to GROUND the SDA line but not sure if it will halt other required communication. This is a safe idea since the SMBUS / I2C lines are open-drain. There is a logic low but never a logic high - the high is always with the pull-up resistors. By design, anyone can pull the line LOW without harm.

The idea is to power up with SDA grounded (on the charging IC) to force the charging IC to see '0'. The host will be communicating with the charging IC to extract out values but curious on the results if you try it. The charging IC also uses the same lines to extract out battery stats.

PS: Have to tend to my dying lawn and fix my sprinkler system - will check back later on your updates.

I connected the SDA to the ground, when I connected the charger to the laptop, the charging light turned on for a moment and then turned off, but the device wanted to turn on after that, the power light blinked a few times and turned off, but the device did not turn on after pressing the power switch. But before grounding the SDA, the device would turn on as soon as the charger was connected.
SDA and SCL ohmic test
From pin 8 and 9 of the IC to the battery connector, both are 327 ohms.

The battery of the device is 6.9 volts. When the device is on with the charger and the battery is on, I have 8.4 volts on the battery, but when I remove the charger, the voltage drops to 6.9 and the device stays on, and the charging light turns on and off due to the lack of voltage. I want to turn off the laptop and start it again, the device does not turn on unless the charger is connected to the device

I will charge the battery for a while, maybe it will go above 6.9

[mon2]

This laptop turns on upon plugging in the AC Adapter? Without using the on/off button?

This is not normal.

[khelane]

Originally Posted by mon2

This laptop turns on upon plugging in the AC Adapter? Without using the on/off button?

This is not normal.

YES
When I connect the charger, the device automatically switches!
I/O is not suspicious (can you be suspicious about the charging light as well?)