Acer Swift SF314-54 charging, not powering up

[mcplslg123]

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

Please note my post#23 for all the newbies here. One wrong step in a hurry may make the board unrepairable. So have patience in diagnosing properly and dont play with voltage injection at the drop of hat. The new gen SOC's wont give you a second chance to fix it.

[kuupotin]

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

As @mon2 has highlighted, it seems something wrong in RTC circuit. I'll suggest to check these first before jumping on the conclusion of defective KBC. I've never seen a bad EC pulling down RTC circuit. If thats the case here, it'll be rare instance. My doubt goes to PCH instead.

01.Resistance on Q1701-All pins
02.Resistance on G1701 pin2.

If resistance on G1701 jumper,pin2 is low, you are very likely staring at a shorted RTC section of PCH. If you are lucky, it could be a shorted cap on RTC lines.

resistances

Q1701:
gate 620 ohm
drain infinite
source infinite

G1701:
pin2 infinite
pin1 ground?

[mcplslg123]

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

Measurement at post#42 are all good except Q1701 Gate. Your PCH seems ok so far. You can try removing the SIO and see if resistance on Q1701 Gate climbs up significantly. If you have the tools and skills, you can just lift the RTCRST pin of KBC to confirm this but be carefull as it require good skill.

Another option is to remove Q1701 and inject voltage on gate to see if anything gets hot. Dont inject more then 1V.

[kuupotin]

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

Measurement at post#42 are all good except Q1701 Gate. Your PCH seems ok so far. You can try removing the SIO and see if resistance on Q1701 Gate climbs up significantly. If you have the tools and skills, you can just lift the RTCRST pin of KBC to confirm this but be carefull as it require good skill.

Another option is to remove Q1701 and inject voltage on gate to see if anything gets hot. Dont inject more then 1V.

Well, strange....

Removed q1701 and measured resistance again. When positive probe on gate there is only 2 ohms, but when reversed probes, it shows 460 ohms.

Tried inject 1V to gate, positive on gate, there was no current. Backwards it took 50mA. WTH...

[mcplslg123]

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

Voltage injection shold be in forward way only-thats black to gnd and red to the target point. Now i'm confused a bit. Black probe to gnd and red to Q1701 Gate measures 2 Ohms as per you and thats a dead short but voltage injection is not taking any current amps-Thats strange. Something is seriously wrong here in RTC circuit. Look for all the caps connected to RTC and try to remove them one by one-just desolder and put them on 1 pad only so that you dont loose them. You can get all the caps connected to RTC rail by searching RTC in schematics and check all the points where it takes you.

[kuupotin]

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

Voltage injection shold be in forward way only-thats black to gnd and red to the target point. Now i'm confused a bit. Black probe to gnd and red to Q1701 Gate measures 2 Ohms as per you and thats a dead short but voltage injection is not taking any current amps-Thats strange. Something is seriously wrong here in RTC circuit. Look for all the caps connected to RTC and try to remove them one by one-just desolder and put them on 1 pad only so that you dont loose them. You can get all the caps connected to RTC rail by searching RTC in schematics and check all the points where it takes you.

After a day I measured gate again. Now it's 100k, positive to gate, negative on ground(copper screw post). No power on board for 24h.

cheesh....

EDIT: and now its infinity. What the .. is going on?

[mcplslg123]

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

You likely have no problem in RTC circuit. perhaps you measured the resistance with adapter connected or immediately after mb was powered. resistance should always be measured with no power and if power is apllied, then one should wait for atlest 2-3 mins to let it discharge.

[sikocan]

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

Give me 2 measurements of the CMOS battery like this:
V when outside the circuit. V when inside the circuit of the CMOS battery.

[kuupotin]

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

Give me 2 measurements of the CMOS battery like this:
V when outside the circuit. V when inside the circuit of the CMOS battery.

Cmos battery new. After connecting to mobo, only very slight drop in voltage. I'll measure it later today.

[kuupotin]

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

You likely have no problem in RTC circuit. perhaps you measured the resistance with adapter connected or immediately after mb was powered. resistance should always be measured with no power and if power is apllied, then one should wait for atlest 2-3 mins to let it discharge.

That might be problem with first measurement. Second measurement was after 24h without power.

[kuupotin]

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

Give me 2 measurements of the CMOS battery like this:
V when outside the circuit. V when inside the circuit of the CMOS battery.

2.94V and 2.93V. It has dropped a little from inserting.
Made a new one. 3.240V and 3.238V..

There is some coil whine when battery or charger attached. Whine stops and starts after a while when pressing reset button on mobo sub board.

[Sephir0th]

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

I don't have the intention to make the confusion here complete but imho there is a display issue in the schematics page of the EC and RTCRST_ON is actually Pin107 instead of 106...

From this assumption Pin 106 should be SYS_PWROK. Continuity check between EC Pin 107 and Q1701 Gate will clarify.

[mcplslg123]

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

I don't have the intention to make the confusion here complete but imho there is a display issue in the schematics page of the EC and RTCRST_ON is actually Pin107 instead of 106...

From this assumption Pin 106 should be SYS_PWROK. Continuity check between EC Pin 107 and Q1701 Gate will clarify.

maybe, the print on that page is bit mislaigned and i wrote about that.

[kuupotin]

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

I don't have the intention to make the confusion here complete but imho there is a display issue in the schematics page of the EC and RTCRST_ON is actually Pin107 instead of 106...

From this assumption Pin 106 should be SYS_PWROK. Continuity check between EC Pin 107 and Q1701 Gate will clarify.

13 ohms..
0.017V with diode measurement

[sikocan]

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

I see, voltages are fine. Keep digging.

[kuupotin]

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

Could my CPU be shorted/bad? Or bios chip?

[a_lik]

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

any update? i've same situation here. rtcrst_on 0v.. but rtcrst# have 3.3v. mine are sf314-56g but smiliar.

[kuupotin]

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

any update? i've same situation here. rtcrst_on 0v.. but rtcrst# have 3.3v. mine are sf314-56g but smiliar.

No updates. I'm stuck...

[a_lik]

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

have you check all sqence? pg 102
where you've stuck?

[kuupotin]

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

have you check all sqence? pg 102
where you've stuck?

I'm just thinking if my BIOS or CPU is bad. No more interest to find fault if there is something bigger going on.

I'm not an expert about reading those sequence things. If I'm reading something wrong there might be days of work with no sense. Laptop will be binned soon.

Big thanks to everybody who tried to help with this thing.