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**mon2** · 05-13-2022, 05:10 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

pu1 pin 4 acdrv is 0.5v
pu1 pin 5 acok is 9.6v
pu1 pin 6 acdet is 0V

The above are bad values. Start with ACDET.

1) This is a voltage that is based on the DCIN (adapter) voltage that will enter a resistor based voltage divider to lower the DCIN voltage to a safe voltage for the charger IC.

See resistors PR31 & PR211. Each must be present and each must be the value shown in the schematic.

2) Meter in DC volts mode (20V is ok).

3) Red meter probe to PR31 -> either side -> black meter probe to ground.

What is the voltage reading ?

Then move the red meter probe to the other side of PR31.

Post your measurements.

If adapter is working then you should have ~19V coming in -> this voltage should be present on one side of PR31.

Confirm it.

Then the LOWER voltage should appear on pin # 6 of the charger IC = ACDET.

Reference:
https://ohmslawcalculator.com/voltag...der-calculator

Attached Files

**vannix** · 05-16-2022, 03:33 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Originally posted by mon2 View Post

The above are bad values. Start with ACDET.

1) This is a voltage that is based on the DCIN (adapter) voltage that will enter a resistor based voltage divider to lower the DCIN voltage to a safe voltage for the charger IC.

See resistors PR31 & PR211. Each must be present and each must be the value shown in the schematic.

2) Meter in DC volts mode (20V is ok).

3) Red meter probe to PR31 -> either side -> black meter probe to ground.

What is the voltage reading ?

Then move the red meter probe to the other side of PR31.

Post your measurements.

If adapter is working then you should have ~19V coming in -> this voltage should be present on one side of PR31.

Confirm it.

Then the LOWER voltage should appear on pin # 6 of the charger IC = ACDET.

Reference:
https://ohmslawcalculator.com/voltag...der-calculator

hi, and thank you for your reply. i would like to tell you that last friday i had already checked the voltage divider and it seemed quite correct (doing the calculation with the ohm values read by the tester should have been about 2.3v). I had therefore assumed that the 24780s had an effect on this voltage divider (with an internal resistance to ground).
this morning i unsoldered the resistances to make the most precise measurement and pr31 seems to be open. I don't know if it was damaged in the tests or if it was already broken.

pr31: 0v --- 19,6v
pr211: 0v --- 0v

pr31: 1m (friday i read 920k)
pr211: 129k (friday i read 130k)

pr31 removed: 3m
pr211 removed: 136k

i don't find 866k R in donor boards, do you think it's safe for test to change pr31 with 422k and pr211 with 66.5k?

EDIT: according to this pdf it seems ok, i'll try asap... https://www.badcaps.net/forum/showpo...12&postcount=2

**mon2** · 05-16-2022, 05:03 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Good link with the new resistor values.

1) You can use the above calculator to validate any resistor combination.

2) The key point is to use the same ratio of the resistors to hit the target voltage.

3) See attached. Your link validates the same. Ok to use the new resistor values you have from your donor board.

Attached Files

**vannix** · 05-16-2022, 05:35 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Originally posted by mon2 View Post

Good link with the new resistor values.

1) You can use the above calculator to validate any resistor combination.

2) The key point is to use the same ratio of the resistors to hit the target voltage.

3) See attached. Your link validates the same. Ok to use the new resistor values you have from your donor board.

same result with new resistors.. 0v on pin 6. but now i'm sure that the resistor value are correct.
the problem could be PQ17 (what does that circuit do?? i'm thinking of removing it...)

Attached Files

**mon2** · 05-16-2022, 05:43 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

What is the voltage @ pin #2 of the PQ17 mosfet ?

It appears to be checking the voltage of the ADP_ID pin and is used to turn ON the mosfet @ PQ17 but that would then cause the ACDET pin to be pulled to 0V.

Measure the ADP_ID voltage on pin # 2 so we can review.

**vannix** · 05-16-2022, 06:20 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Originally posted by mon2 View Post

What is the voltage @ pin #2 of the PQ17 mosfet ?

It appears to be checking the voltage of the ADP_ID pin and is used to turn ON the mosfet @ PQ17 but that would then cause the ACDET pin to be pulled to 0V.

Measure the ADP_ID voltage on pin # 2 so we can review.

pq17 is not shorted and ADP_ID is 9,3v (1/2 of VA), i can find it also in the dc connector.
i dont understand what it does, the dc connector only has + and -, it hasn't ID pin.
The voltage of 9v is given by the voltage divider on the board, so it has no contact with the connector. The only explanation i think is that the connector is broken and must have a return on the adp-id when a connector is plugged in (like the sense of the audio jack)

EDIT: the dc connector is broken. there is a bent pin that does not make good contact with ground when the connector is inserted. manually shorting apd_id to ground results in about 2.7v on acdet but, again, there is no 19v after PQ1

**mon2** · 05-16-2022, 07:29 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

2.7v on acdet but, again, there is no 19v after PQ1

Good value of ACDET. The PQ1 is a different fault and is very common.

Remove all power. Meter in resistance mode.

Check the resistance across the mosfet pins to check if it is defective.

Source (1-2-3) & Drain (5-6-7-8)
Source (1-2-3) & Gate (4)
Gate (4) & Drain (5-6-7-8)

Post the above readings for PQ1 and then again for the next mosfet that follows. A low reading = defective mosfet.

Next, measure the voltage @ GATE of each of the first 2 mosfets.

Recommend to do the above with NO POWER (NO BATTERY). When checking the gate voltage - do so with only the external power adapter.

The good value of ACDET is now informing the charger IC that a valid power adapter is mated to the logic board. This will allow us to move forward.

**vannix** · 05-17-2022, 01:59 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

in resistance mode all measurement result in infinite resistance. by exciting the gate of both fets with another tester in diode mode they measure about 1ohm in source-drain, so PQ1 and PQ9054 seems ok.
the voltage are the following:

PQ1 pin 4 gate = 0.1v
PQ1 pin 1-3 source = 0.2v
PQ1 pin 5-8 drain = 19,6v

PQ9054 pin 4 gate = 0.2v
PQ9054 pin 1-3 source = 0.1v
PQ9054 pin 5-8 drain = 0.2v

i think the problem is still related to the bq24780s

EDIT: ACOK is 0V, but vcc and acdet are ok, so the problem is still related to the battery charger.. chinese ic fails??

Attached Files

**mon2** · 05-17-2022, 04:44 AM

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.

**vannix** · 05-17-2022, 09:47 AM

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** · 05-17-2022, 10:21 AM

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.

Attached Files

**vannix** · 05-18-2022, 03:29 AM

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** · 05-18-2022, 03:56 AM

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** · 05-18-2022, 04:04 AM

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** · 05-18-2022, 04:13 AM

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** · 05-18-2022, 04:38 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Originally posted by mon2 View Post

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** · 05-18-2022, 04:53 AM

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 ?

Attached Files

**vannix** · 05-18-2022, 05:11 AM

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Originally posted by mon2 View Post

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** · 05-18-2022, 05:18 AM

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.

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

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

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