Acer ES1-512 series wont turn on

[baddjavo]

laptop: Acer es1-512-C79X
model no: MS2394
S/N: NXMRWEX01152004e64660
mb: EA53-bm/EG52-BM MB 14222-1 448.03707 0011

Few days iam trying to figure why wont turn on after pressing pwrbtn.
I have 3v on pwr btn.
3V and 5v not present (if i short ecrst# pin 85 on EC chip then 3 and 5v present)
Probably missing signal on EC chip, but i dont know which one.

[baddjavo]

Let close this thread. Finally i have found that pu5001 working properly but getting hot, taking so much amps.... traced short over pu3601 out ... and then short lead me to c2729 ! Its a BADCAP !
Thank to all percipients. BADCAP !!!

[mon2]

Check the earlier power sequence signals.

[baddjavo]

Thank you for answer. Please can u specify where to find RTC_AUX_S5 on which component.
RTC_RST# = 3V that not good, line going only to cpu.
3D3V_AUX_S5 = 3v
3D3V_RTC_AUX = 3v
5V_AUX_S5 = 5v
ECRST# = 3V

[mon2]

If the earlier lines are logic ‘1' then you are ok.

In your first post, what did you do to pin 85 to make the power rails work?

[baddjavo]

RTC_RST# should be ZERO, coz #, this is not good.
ECRST# should be ZERO.
I just short to gnd pin 85 with tweezers, and 3v and 5v always voltage started.

[mon2]

Study who is driving the ECRST# signal. That driver circuit needs to be reviewed. If it is the EC then check the power, check the clock. Maybe the EC bios is corrupt.

[baddjavo]

ECRST# signal is generated by EC chip dropping voltage to zero probably mosfet inside EC. This is initialization stage BIOS coming later. I think EC chip is good.

[mcplslg123]

RTC_RST# should be ZERO, coz #, this is not good.
ECRST# should be ZERO.
I just short to gnd pin 85 with tweezers, and 3v and 5v always voltage started.

Wrong. ECRST# & RTC_RST# both should be 3.3V. You need to understand the suffix # a bit more.
If ECRST# is say 0V that means its in RESET mode .When its at 3.3V it means its has reset itself.

[baddjavo]

Ok. If i get it, ecrst# is impulse for short time, then returns to 3.3v for EC normal mode. So i should try to change bios ?
Can u explain why 3v,5v regulator working when short ecrst# to zero ?
Didnt find any shorts on board. Laptop used on battery then sudden shut down, after that laptop wont turn on.

[mon2]

The reset line is active low, denoted with the '#' suffix. When this signal is LOW, the RESET state is active. After a period of required time, this signal must release the logic LOW level and return to a logic HIGH = ~3 volts. Only then will the components being driven by this signal start execution.

When you use the tweezers, your logic low level is long enough to perform this task.

So,

1) either the EC is never performing the EC reset pulse from LOW to a HIGH.
2) or the pulse on this line is too short of a duration to perform the reset action

Does the board power up normally after you perform this tweezer short action?

The EC is a stand alone microcontroller (8051 / ARM, etc.) and has its own firmware. Often a local flash device or internal to the EC controller. Sometimes, the main PCH / CPU will spoon feed the firmware over it's communication lines. Either way, yes, it is worthwhile to make a bios backup and reflash it with a known good one for further testing.

[baddjavo]

I think i get it.
Board not powering up after tweezer shot.
Still dont have ec programmer.
I will take bios backup.

Update. I just noticed after pressing pwnbtn laptop is trying to start giving short faint blink on power led, and voltages coming from 3v.5v reg, only for a moment.

[mon2]

Ok. Start with the basics. Review the charger IC thread sticky (above) by piernov.

Remove all power. Measure the resistance to ground of the main power rail that follows after the 2 x DCin mosfets.

We are checking if there is any shorted part on the board.

Measure the resistance to ground on pin # 1 of the charger IC @ PU4403. This rail should not be with a low resistance.

What is the exact resistance in ohms?

[baddjavo]

Ressistance in Kilo or Mega, and voltage in picture. All mosfets good.

[baddjavo]

After searching for possible shorts i have found that one of mosfets pu5003 is shorted sourse drain side, but gate is not. Its surprising that lower mosfet died usually that is upper.
So i removed mosfet then after pressingpower button blue led light on ! Then i changed mosfet and nothing! Same place where i started.uhm
On oscilloscope i found mosfet gate signal no impulses so probably controller also died...

[baddjavo]

Let close this thread. Finally i have found that pu5001 working properly but getting hot, taking so much amps.... traced short over pu3601 out ... and then short lead me to c2729 ! Its a BADCAP !
Thank to all percipients. BADCAP !!!

[mon2]

Excellent find. Thanks for the closure.