Acer Sf314-41 power issue

[claws77]

my laptop has a weird power-on issue.
Once the laptop has been powered on, it can restart/ wake just fine on battery power or Adapter, ONLY If i have not closed the LCD.
If i am running on battery and have closed the LCD (even momentarily). it will not power-on/ wake-up on battery power no matter the battery percentage.

but once i open the LCD and connect it to the adapter (even momentarily) it will wake up gain and I wont experience any issues till i close the LCD.

i do not know where to look for repair.
thank you all for any advice.

[mon2]

Can you link the schematics for this board? Only if they are in the dedicated schematics forum.

[claws77]

Can you link the schematics for this board? Only if they are in the dedicated schematics forum.

https://www.badcaps.net/forum/troubl...bow-pk-18848-1
this webpage has them.

[mon2]

Review the voltage to ground of the LID_CLOSE# signal. Since there is a '#' suffix in the netname, this is an ACTIVE LOW signal. This means that if this line is logic LOW = ~0 volts, then the LID is considered to be closed. Respectively, if the LID is open, this signal line should be pulled to a logic HIGH level of ~3v3 through pull-up resistor @ R2468. If you do not see these states, then review the voltage on each side of R2468.

Post each measurement.

[claws77]

Review the voltage to ground of the LID_CLOSE# signal. Since there is a '#' suffix in the netname, this is an ACTIVE LOW signal. This means that if this line is logic LOW = ~0 volts, then the LID is considered to be closed. Respectively, if the LID is open, this signal line should be pulled to a logic HIGH level of ~3v3 through pull-up resistor @ R2468. If you do not see these states, then review the voltage on each side of R2468.

Post each measurement.

sir, i have reviewed AFTP72 which is connected to pin 1 of LID_CLOSE#

my findings
on battery power this point reads 0.068V (Black probe to GND, red probe to test point of multimeter) in closed state of LID but when i open the LID this point still reads 0.068 V on battery power
on AC power, this point reads 3.312V. in open LID position
once AC power is removed in LID open state it still reads 3.312 V on battery power.

so yes this LID_CLOSE# signal is faulty. Thank you. How to repair this? Sorry for delay in reply

[claws77]

IOBD 1 is the problem, removing it solves the problem.
reconnecting it makes the problem come back.
how to repair this board?

strongbow_KL_LED_CARD_MB 17824-1

[mon2]

See attached. Confirm that your RTC battery is ok - may need to be replaced. This is required to create the pull-up voltage when the power adapter is absent.

Also confirm that the dual common cathode diode @ D2501 is functional. You can check it with DIODE mode of your meter. Remove all power. Meter probes on each anode / cathode pair; diode should conduct in one direction but block if the meter probes are reversed (cathode / anode). Repeat for the other diode inside this sot23-3 package.

[claws77]

RTC battery voltage is 3.096 V
D2501 is ok? reads .288 in one direction and OL in reverse polarity. for both pairs 1-3 and 2-3

on just RTC connected pin 2 is 3.09 V and pin 1 is 0, pin 3 is 2.976V

I think that the issue is daughter board. removing it the laptop turns on fin even on batttery power and the voltage at ATFP72 is also ok but connecting the IOBD 1 the voltage drops to 0.68 V.

[mon2]

What is on this iobd? Are there schematics available for this add on board? With no power, mate this board and check the resistance to ground of this lid sensor pin. You can also test in diode mode. Inspect this board for any physical damage.

[claws77]

IOBD seems to be I/O board, it has a usb port, card reader. LEDs. Fingerprint. there are no visual damages.
There is no schematic available for this board
the resistance to GND is 142.1 kohm

removing the IOBD AFTP72 shows 0 V on RTC and 3.303V on RTC + Battery
attaching the IOBD AFTP72 shows 0.77 V on RTC and 0.68V on RTC + Battery

[mon2]

The same 3v3 rail from pin #3 dual diode must be used by this defective iobd.

Confirm it with the boardview file that this iobd connector uses this low current rail.

Then check the resistance to ground of this rail with and then without the iobd plugged in.

Post pics of this iobd. Someone is shorted onboard. Could be a tvs esd device used by the usb port or card reader.

[mon2]

See attached. With your meter in DIODE mode and without any power to the board -> connect your IOBD. Then proceed to measure each contact on this connector in DIODE mode. Red meter probe to ground, yes RED. Black meter probe to the pin to test.

We are hunting for any line with a low measurement which means that line is shorted and is of concern. Post your measurements.

[claws77]

See attached. With your meter in DIODE mode and without any power to the board -> connect your IOBD. Then proceed to measure each contact on this connector in DIODE mode. Red meter probe to ground, yes RED. Black meter probe to the pin to test.

We are hunting for any line with a low measurement which means that line is shorted and is of concern. Post your measurements.

third column is with reference(red probe) to daughter board's usb casing.
4th collumn is with reference(red probe) to main board's usb casing.

[mon2]

To confirm, the iobd is disconnected and the measurements were taken.

Then the iobd was attached and the measurements were taken again.

Is this correct?

Confirm the measurement of pin #23 on the iobd connector.

[claws77]

you are right 3rd column 7 is OL and 23 is .555

[mon2]

Measure the voltage to ground of pin #8 with and without this iobd board.

[claws77]

Green means Repeatable values
inc means increasing
dec means decreasing

non colored values means that they are non zero but change as i keep measuring it 2nd and 3rd time

both colums are measured 3 times to check for repeatability.

[mon2]

See attached. The signals marked with the red arrows are shorting out once you attach the IOBD.

Start with the USB4 connector -> nearby may be a TVS ESD diode array. Share close up pictures of this region. That part should be removed and then the USB4 signals should return to a normal range. This may also correct the voltage rail on line # 8.

[claws77]

thank you greatly for giving your time to help me. many thanks

[mon2]

See attached.