Acer A315-55G / DA0ZAWMB8E0 not charging [SOLVED]

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Check the resistance to ground of each large coil. Remove all power.

Something is causing the power rail to shutdown. Start with the 3v3 rail used for the ILIM pin.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

This is odd and believe it should not be 0v. Will review a bit later. See the datasheet for details of this pin. If 0v, there is nothing to do.

In the datasheet i don't find detailed info, and even online there isn't information for 24780s related to ilim.
However when +VIN is present there is 3.3v on +3VPCU and this brings power to ILIM. I therefore believe that it is not essential for enabling ACDRV.
It could be a cap or a resistor that is damaged somewhere but i'm starting to get bored and there are many more repairs in the queue

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

This is odd and believe it should not be 0v. Will review a bit later. See the datasheet for details of this pin. If 0v, there is nothing to do.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

What is the voltage of pin #21 = ILIM ?

This must be a ref voltage value > 0v to function.

pin 21 ilim is 0,049mv, but PR15 is not present in this board

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

What is the voltage of pin #21 = ILIM ?

This must be a ref voltage value > 0v to function.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Sorry for double post but i can't edit anymore the last one..

Some updates:
1) The ACIN pin in the ITE chip is probably programmable as input/output, when the EC is powered on i read 2,8v, so the chip should be ok.

2) There isn't any mechanical problem (i think). I tried folding, heating or cooling and nothing changed.

3) When the dc voltage is less than 17v (acdet < 2,4v) the ACOK is floating and is not pulled low. increasing input voltage, after about half a second that acdet > 2.4v, the acok pin goes low.
In this time sometimes there is an instant where there is 2-4v after the 2 mosfets pq1 and pq9054. then it returns slowly to 0v (probably for capacitor discharge).
At this point i believe there are 3 options:
-a) the 24780s chip is fake, it doesn't work, the chinese programmer who engineered it was drunk
-b) the 24780s chip must be programmed using smbus or internal registers as mentioned in the datasheet
-c) there is a problem with some component in the charging circuit and the 24780s goes into protection immediately (paragraph "7.3.9 Device Protections Features" of the manual)

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

OMG.

1) Were the chips sourced through Aliexpress ?

here are some shops we trust and have used often:

https://www.aliexpress.com/item/3279...05588192%21sea

https://www.aliexpress.com/item/3286...36471688%21sea

https://www.aliexpress.com/item/1005...76906162%21sea

2) You are in pretty deep on this repair - perhaps consider one more trace cut to isolate the ITE EC ? Then we will know with confidence that the voltage divider must match what was calculated.

After this validation, consider to order a fresh batch of the charger IC and maybe even the ITE controller from another shop.

yes, from aliexpress, but from another seller

i can try to isolate the EC, however.. a strange thing happened. I disconnected the power supply from the 220v, after some seconds (when the 19v voltage started to drop) i touch the 19v connector and i'm sure that the fan starting spin for an instant. Tried again and again with the tester connected, but only another time happened that just inserted the power supply i read about 8v after the pq9054. this means that pq1 and pq9054 have been closed for an instant!
probably something goes into overvoltage protection? maybe there is a mechanical problem with the board in the connector area?
I'm doing some more tests, then i'll let you know!
in the meanwhile thanks again

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

OMG.

1) Were the chips sourced through Aliexpress ?

here are some shops we trust and have used often:

https://www.aliexpress.com/item/3279...05588192%21sea

https://www.aliexpress.com/item/3286...36471688%21sea

https://www.aliexpress.com/item/1005...76906162%21sea

2) You are in pretty deep on this repair - perhaps consider one more trace cut to isolate the ITE EC ? Then we will know with confidence that the voltage divider must match what was calculated.

After this validation, consider to order a fresh batch of the charger IC and maybe even the ITE controller from another shop.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

i am pretty sure of the welding of the spare part. i do this very often and rarely have problems. the only doubts are about the origin of the chips (it happened to me that chips from china were fake).
it could be a problem with the ITE chip, but not with the firmware because the board works with the battery
however i cutted the trace between the charger and the voltage divider and there is another strange situation.. 0v on the charger side, but also 0,754v on the voltage divider side, so the problem is in the charger, but also in the EC?

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Based on the posted measurements, believe that the charger IC is pulling this line down.

I know that this part has been replaced a few times. Are you confident on the reflowing of the replacement part ? Lots of flux & heat but low air pressure to make the component sink onto the pads.

Personally do not have experience with the ITE controller so not sure if it has blown out its firmware - welcome comments from others. That is, if there is firmware on this EC controller, can this GPIO pin become an output and pull down this voltage divider rail ??

Do not think so at this time as the default of GPIO pins is an input mode and the rail does not look to be shorted (from the diode reading).

So this leads to the charger IC driving this pin low due to some fault or voltage not reaching the charger IC pins.

Perhaps, gently consider to reflow the IC and test again. Only if you feel comfortable, consider to find a sweet spot to cut the trace from the IC to the voltage divider resistors. Then for sure we will know who is pulling down this line.

A slight cut with the tip of an x-acto knife blade should do it. The more difficult task is to restore the same cut trace. Scrape the green solder mask to expose the cut trace for soldering with a piece of wire.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

No - wait - no cutting of traces and do not inject voltage, yet. So they must be using a direct PCB trace for the PR30 location on the PCB.

Something is pulling this voltage divider rail to 0v - it could be the charger IC but it will do so if the conditions of ACOK are not met.

Or another external factor. The ACIN trace enters the ITE chip and each mode of this pin is an INPUT style of port pin. Unless the ITE chip is defective, it will not pull down this signal rail.

Confirm that ACDET voltage is reaching the charger IC @ pin # 6. Carefully measure directly on the charger IC to confirm the chip is able to read this voltage.

Then remove all power. Wait a minute to allow for discharge of the caps.

Then meter in DIODE mode.

Red meter lead to GROUND.
Black meter lead on point #2 = between the 2 resistors (PR39 & PR40).

What is the reading in DIODE mode ?

ACDET reach the ic (2,649v on pin6)
in diode mode it measure 0,502v

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

No - wait - no cutting of traces and do not inject voltage, yet. So they must be using a direct PCB trace for the PR30 location on the PCB.

Something is pulling this voltage divider rail to 0v - it could be the charger IC but it will do so if the conditions of ACOK are not met.

Or another external factor. The ACIN trace enters the ITE chip and each mode of this pin is an INPUT style of port pin. Unless the ITE chip is defective, it will not pull down this signal rail.

Confirm that ACDET voltage is reaching the charger IC @ pin # 6. Carefully measure directly on the charger IC to confirm the chip is able to read this voltage.

Then remove all power. Wait a minute to allow for discharge of the caps.

Then meter in DIODE mode.

Red meter lead to GROUND.
Black meter lead on point #2 = between the 2 resistors (PR39 & PR40).

What is the reading in DIODE mode ?

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Ok. Good.

There is a resistor or solder blob between point #2 and point #3.

Remove this part (pr30) or short.

Then check the voltage again without this resistor.

Measure at point #2 with dc adapter only.

I already check but unfortunately there is nothing to remove. I should cut the track with a cutter but it is very small and the board has many layers, i think i'll damage the 2nd layer

you can see the picture in the post 5: https://www.badcaps.net/forum/showpo...26&postcount=5
(pr39/40 are the 2 black resistor without the value label in the first photo, opposite side of 24780)

if you think it's safe i can inject 2 or 3v in point #2 to check the voltage divider

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Ok. Good.

There is a resistor or solder blob between point #2 and point #3.

Remove this part (pr30) or short.

Then check the voltage again without this resistor.

Measure at point #2 with dc adapter only.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

the resistors (soldered on pcb) measure:
PR39 85,9k
PR40 86,2K

point 2 to ground is 86,2k (the same as pr40)

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Remove all power.

Meter in resistance mode (higher than 100k scale).

Check the resistance with probes on point #1 and #2.

We want to check the resistance of this resistor.

Next, check the resistance to ground of point #2 and ground.

Post the measurements. No power for each test.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

1: 5,94v
2: 0,00v (0,0021)
3: 0,00v (0,0021)


i also tried another (new) 24780s with same identical result

ACOK from datasheet says:

Active HIGH AC adapter detection open drain output. It is pulled HIGH to external pullup supply rail by external
pullup resistor when a valid adapter is present (ACDET above 2.4 V, VCC above UVLO but below ACOV and
VCC above BAT). If any of the above conditions is not valid, ACOK is pulled LOW by internal MOSFET. Connect
a 10-kΩ pullup resistor from ACOK to the pullup supply rail.

but all conditions seems valid



is a hopeless repair

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

1) ACOK is not OK. Under the posted measurements and as documented in the TI datasheet, pin # 5 should be HIGH. However, this is an open-drain pin so the logic high really means the pin will be 'floating' like an open switch.

For this reason, an external resistor must be used for the 'pull-up to a soft high' and this resistor is @ PR39.

2) See attached. Confirm the voltage measurements with the adapter connected on the requested points of interest @ 1, 2 and 3.

PR39 is pulled high using the LDO regulator pin # 24 = ~6 volts.

So this same voltage should appear on one side of PR39.

Noting that the ~6 volts is too high for logic ICs, TI is using a resistor based voltage divider with the PR39 and PR40 resistors.

Each is the same value (or should be). So the output voltage (between the 2 resistors) should be 50% of the ~6 volts and be presented onto ACOK rail.

Confirm the measurements of each.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Pq1 bq24780s voltages:

Pin 1 : 0,00
Pin 2 : 0,00
Pin 3 : 0,05
Pin 4 : 0,35
Pin 5 : 0,00
Pin 6 : 2,65
Pin 7 : 0,20
Pin 8 : 0,00
Pin 9 : 0,00
Pin 10 : 0,00
Pin 11 : 0,25
Pin 12 : 0,06
Pin 13 : 0,00
Pin 14 : 3,13
Pin 15 : 0,02
Pin 16 : 0,00
Pin 17 : 0,22
Pin 18 : 0,25
Pin 19 : 0,22
Pin 20 : 0,22
Pin 21 : 0,00
Pin 22 : 0,00
Pin 23 : 0,00
Pin 24 : 5,94
Pin 25 : 5,61
Pin 26 : 0,22
Pin 27 : 0,22
Pin 28 : 19,45

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Measure the voltage on each pin of the charger IC using only the external dc adapter (no battery). Do this carefully to avoid damage from slipping of the meter probes.

Post each measurement.