Acer Swift SF314-54 charging, not powering up

[kuupotin]

Hi all.

I have Acer Swift SF314-54 which is charging (after battery reset, red charging light which turns blue when full) but when I'm trying to power it up by pressing power button, nothing happens. Actually if laptop is connectec to PSU and blue charging light is on and I'm pressing power button, blue charging light turns off. After this I have to make battery reset again to get blue light back.
Also when psu is not plugged, there aro no lights on led. No lights when power button is pressed. Never seen light in power led.

Mobo looks very clean without any water etc damage. I'm not able to power laptop from mobo by shorting keyboard edge pins when ribbon is not connected.

Where to start?
Tried to reconnect every ribbon and connector on mobo, no luck. Bios battery changed. RAM, SSD etc, no luck. There is surely something wrong on mobo.

There are some shorted capacitors near cpu but that might be ok.

[Sephir0th]

Re: Acer Swift SF314-54 charging, not powering up

I'd start with a basic overview of the power rails of the board. Which voltages are at coils present without pressing the power button, which are present while/after pressing the power button. What resistances to GND (range 200) do you measure at the various coils. Like that, to start with. Assuming a basic understanding of how to use a multimeter.

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

Applied 19V to power connector and get these kind of measumements. All other coils are zero. This without pressing power button. Couldn't find 3.3V rail...

[Bonzas]

Re: Acer Swift SF314-54 charging, not powering up

Applied 19V to power connector and get these kind of measumements. All other coils are zero. This without pressing power button. Couldn't find 3.3V rail...

What do you mean can't find 3.3v rail ? do you have schematic or boardview your motherboard ?

code board ?

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

No schemas. Strongbow_kbl_mb 17863-1

Found 3.2V from keyboard connector. Tried to start board by shorting two outermost pins, no change in coil voltages.

[Bonzas]

Re: Acer Swift SF314-54 charging, not powering up

No schemas. Strongbow_kbl_mb 17863-1

Found 3.2V from keyboard connector. Tried to start board by shorting two outermost pins, no change in coil voltages.

Schematic here

https://www.badcaps.net/forum/showth...13#post1203113

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

Thanks.

Looks like PU4501 (SY8288BRAC-GP) is heating a little bit when powering mobo by shorting pins.

I have a very little of experience with mobo repair. I have fixed some mobo by voltage injection and checking which component is heating.
This thing is a lot more difficult.

[mon2]

Re: Acer Swift SF314-54 charging, not powering up

Come on over to the dark side and help us repair more crapware.

Do you have a hot air tool? Flux? Tweezers? Perhaps a dead board for training?

If not, can send you some links for such tools.

If you are not in a rush, this QFN package is simple to replace.

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

I have everything. Tools, hot air, soldering tools etc Actuallu just loaned a thermal camera from friend.. Replacing components is not a problem.

Just thinking that is it a correct component? It is slightly warm when powering and cools quite fast. Mobo takes a low current spike before shuts down.

[Bonzas]

Re: Acer Swift SF314-54 charging, not powering up

I have everything. Tools, hot air, soldering tools etc Actuallu just loaned a thermal camera from friend.. Replacing components is not a problem.

Just thinking that is it a correct component? It is slightly warm when powering and cools quite fast. Mobo takes a low current spike before shuts down.

So you need to make sure again if all voltages present. You may need read carefully on schematic that show power squence on your board. Where is coil or pad that doesn't have output voltages. Some chip have pwrgood signal to communicated with other part

[mcplslg123]

Re: Acer Swift SF314-54 charging, not powering up

Since you have schematics, measure resistance on 3V LDO(LP). It should be measured without any power connected.

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

Since you have schematics, measure resistance on 3V LDO(LP). It should be measured without any power connected.

Do you mean PWR_3D3V_LDO?
This was 22k when measuring from PR4501 pin 17 to ground. I noticed that 3.3V was present.

[mcplslg123]

Re: Acer Swift SF314-54 charging, not powering up

Do you mean PWR_3D3V_LDO?
This was 22k when measuring from PR4501 pin 17 to ground. I noticed that 3.3V was present.

Measurement is good. What about 3V_EN/3V_5V_POK/PWR_3DV3_PG ? You may need to switch the board to take measurements.

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

Measurement is good. What about 3V_EN/3V_5V_POK/PWR_3DV3_PG ? You may need to switch the board to take measurements.

Cannot switch board. After powering 3V_EN stays 3.3V few seconds (PU4501 pin12).

No life in 3V_5V_POK and PWR_3D3V_PG

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

Cannot switch board. After powering 3V_EN stays 3.3V few seconds (PU4501 pin12).

No life in 3V_5V_POK and PWR_3D3V_PG

I mean that board doesn't stay powered, only few seconds. No status change on power led, stays off.

[mon2]

Re: Acer Swift SF314-54 charging, not powering up

Remove all power. Meter in resistance mode.

Check the resistance to ground of each and every coil / inductor on the board.

Each such coil / inductor is linked to a local power supply rail. If the resistance is low, there is a shorted part (capacitor??) on that rail needs to be removed / replaced.

Otherwise the low resistance is being sensed by the current sense loop and forcing that local regulator to power OFF to prevent further issues.

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

Remove all power. Meter in resistance mode.

Check the resistance to ground of each and every coil / inductor on the board.

Each such coil / inductor is linked to a local power supply rail. If the resistance is low, there is a shorted part (capacitor??) on that rail needs to be removed / replaced.

Otherwise the low resistance is being sensed by the current sense loop and forcing that local regulator to power OFF to prevent further issues.

Checked every big inductor. There was two low resistance ones and two slightly higher. Voltage injection didn't gave any hint. CPU is heating a little, good or bad sign?
Coils on lower left side of cpu.

Voltage injection to this coil. Lowest resistance to ground.

[mon2]

Re: Acer Swift SF314-54 charging, not powering up

It is risky to use voltage injection too early till we know more about the state of the logic board.

What voltage was used for the voltage injection?

[kuupotin]

Re: Acer Swift SF314-54 charging, not powering up

It is risky to use voltage injection too early till we know more about the state of the logic board.

What voltage was used for the voltage injection?

1V, 2A limiter

[Sephir0th]

Re: Acer Swift SF314-54 charging, not powering up

Am I the only one here who have issues with the pictures shared here? They're way to small. I can't identify anything