Asus UX534FT No ALW voltages

[koby058]

Hi

The owner replaced an NVME stick since then the laptop not powering on.

Probably he did not disconnect the battery but i don't know for sure.

Main power rail is present with 20v but not other power is present.

When looking with thermal cam i saw the 2N = chip and some chip under the nvme is getting warm.

upon removal of the "other" chip. the 2N (RT8249CGQW) chip is not getting warm any more.

the 2N have power entering its VIN pin 12 20V and its LDO3 pin3 is outputting 3.3v.

but both enable pins voltages are not present. EN2 100k ohm, EN1 10k ohm

attached a schematic that i found online i think it is only similar not exactly the one.

Can you please help me inspect it ?

[SMDFlea]

Re: Asus UX534FT No ALW voltages

attached a schematic that i found online i think it is only similar not exactly the one.

Schematic copied to new thread so that others can find it when using the forum search -> https://www.badcaps.net/forum/showthread.php?t=119891

Reminder: rules and organization of this section
https://www.badcaps.net/forum/showthread.php?t=117483
.

[mcplslg123]

Re: Asus UX534FT No ALW voltages

Very likely EN1/EN2 will come only after triggering the motherboard.Check resistance of 3V LDO/5V LDO rails, then move on to check requirements of SIO. Is it charging battery? What is the standby consumption on dc supply?

[koby058]

Re: Asus UX534FT No ALW voltages

Hi

Not charging

0 consumption on power supply

resistance is pretty high on all coils

it is a BGA SIO so it is super hard to test with out boardview

Any other ideas ?

[Sephir0th]

Re: Asus UX534FT No ALW voltages

Could be worse. Take a look at PU8803, a dual load switch with common footprint. Here you can check whether the 3V for the EC are enabled and outputted at all

[koby058]

Re: Asus UX534FT No ALW voltages

Hi

When looking with thermal cam i saw the 2N = chip and some chip under the nvme is getting warm.

upon removal of the "other" chip. the 2N (RT8249CGQW) chip is not getting warm any more.

This is super funny. it appears that the "other" chip that i removed is APL3533 which is the load switch.

[Sephir0th]

Re: Asus UX534FT No ALW voltages

You're likely dealing with a shorted output of +3VA_EC then, which almost always means shorted embedded controller...

[koby058]

Re: Asus UX534FT No ALW voltages

Well, ATM the L3533 is out of the board and i measure its output pins and it is having 0.02 ohm So i guess its the end of the line for me. i dont have an EC programmer.

[koby058]

Re: Asus UX534FT No ALW voltages

Do you know if any body sell those pre ptogrammed?

[mcplslg123]

Re: Asus UX534FT No ALW voltages

Sorcing a reliable BGA ec is bit tough. My experience so far is pretty bad.Most of the time EC cant be programmed-they are a nightmare to program thru JTAG.May be need to learn more.

[koby058]

Re: Asus UX534FT No ALW voltages

Hi

Thanks for your reply, i did replace the chip and it was auto programmed. now the laptop turns on and boot to windows.

The issue is that it is not charging and on windows it showing the battery have 225% power

Can someone please help me debug this ? the charger IC is BQ24780s

[Sephir0th]

Re: Asus UX534FT No ALW voltages

Hi

Thanks for your reply, i did replace the chip and it was auto programmed. now the laptop turns on and boot to windows.

The issue is that it is not charging and on windows it showing the battery have 225% power

Can someone please help me debug this ? the charger IC is BQ24780s

Start with the DC-IN Mosfets maybe one of them is internal shorted.

[koby058]

Re: Asus UX534FT No ALW voltages

Both mosfets have Mega ohms between: s to d, s to g, d to g

SDA is 3.26v
SCL is 0.38v

trying second battery (NEW)

when on battery, laptop does not turns on but when turning it on with battery connected then removing the AC adapter the laptop remains on.

[mon2]

Re: Asus UX534FT No ALW voltages

Hey! Finally watched the last episode of Fauda. Doron, what a ham!! Always leaving enough room to have another season. Love it.

SCL is 0.38v

Too low. Remove the battery. Does this SCL voltage return to normal ~3v ?

If not, locate the ESD diodes that should be nearby the battery connector. It will need to removed.

[mcplslg123]

Re: Asus UX534FT No ALW voltages

SCL pulled low may be even for a defective EC.However, do check the esd diodes and resistors in between battery connector to SIO for SCL.

[koby058]

Re: Asus UX534FT No ALW voltages

Mon2 i am happy you enjoying Fauda so much

SCL still low without batt. when you say diode do you mean PD6001? if yes it is not soldered on this board

resistance of PR6002 is 330 ohms

resistance of SCL line to GND is 640 ohms

mcplslg123, this is a new EC chip i bought from SHUMS.

what do you think guys ?

[mon2]

Re: Asus UX534FT No ALW voltages

Locate the required pull up resistors for these SCL and SDA pins. Being an open drain interface, there must be a pull up resistor on each pin to create the soft high state.

Once found, check the voltage to ground on each side of this pull up resistor.

Then remove all power and confirm the resistance of this resistor. Often the recommended pull up resistance is 2k2 but can be any value upto 10k (from our testing on some designs). Either way, it must not be missing.

[koby058]

Re: Asus UX534FT No ALW voltages

Thanks, i will try that and post, do you see this resistor in schematics ?

where should it be in your opinion? near EC, Charger IC, batt conn ?

[mon2]

Re: Asus UX534FT No ALW voltages

I do not have the exact schematic for this logic board but found a similar one.

Review R3013 and R3020. Confirm they are present and check their voltage to ground on each pin.

[koby058]

Re: Asus UX534FT No ALW voltages

Hi

On R3013, there is 3.3n on the right side and 0.46 on the left side

resistance on resistor is 4.5K ohms.

right side to Ground 5.2k ohms

left side to groung 800K ohms