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

[mcplslg123]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

The moderator of the forum should mark a thread "solved" after succesful resolution somewhat like elvikom.pl forum.

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Well done and thanks for updating the thread.

It is vital that others do the same and not go and hide after the work is done. We have all invested a great deal of time to troubleshoot the defective product(s) - respectively, want this forum to be a knowledgebase for future readers. Only then does it make sense for us to be here.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

the new bq24780s from mon2's chinese seller has solved the problem.

while connecting cd jack:
ACDRV 0->~5v->25,5v
CMSRC 0->~7v->19,5v
ACOK 0->3,1v->3,1v

then stable:
ACDRV 25,5v
ACOK 3,1v

battery is charging, nothing is heating, no strange noises, 1.2-2.5A current draw with windows started and battery charging.


thanks to all users those who helped me in the repair and (especially) in understanding the operation of these chargers. it will be very useful for next time.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Tiger (TI FAE) has posted full details on the above linked TI support forum.

1) Inspect the cap on the REGN pin. It is required and is critical.

2) Remove all power and confirm that both ACFET & RBFETs are not defective.

3) Once ACDET is confirmed to be > 2v4, Vcc to the charger IC is high enough (19v), REGN will turn ON to supply 6 volts higher than CMSRC to the gates of the n-channel mosfets. CMSRC is zero at the start of this cycle.

Then ACFET will turn ON and since the gates are common for the first 2 mosfets, so will the RBFET and the AC adapter voltage will reach B+.

Confirm that the current sense legs of the B+ rail are properly reaching the charger IC so that the charger IC does not feel there is a need to shut down this process which appears to be the case for your logic board.

Confirm the resistance from each leg of the current sense resistor back to the charger IC. A wrong value will fool the charger into believing there is too much load so the mosfets should be shut off.

Do review the TI forum thread for a proper explanation from Tiger.

Continue to post your updates. This is a very good topic to assist in future repairs.

Update - from a quick review of your last post - replace the RBFET (ie. 2nd mosfet that links to the B+ rail). Confirm the cap on REGN is a good capacitance - replace it if you have another cap that is 2.2uf or higher (6 volt or higher rating).

In these days i have replaced everything possible (in addition to what you suggested) without changes, but from this morning i can say that the problem with probability 99% is not due to the board and not even to the components, but only to the bq24780s.
This morning i got from a customer another faulty board with 24780s that turns on but sometimes it doesn't recognize/charge the battery.
I swapped the 24780s, and the problems swapped too.
Now the pc turns on also with the power supply (all values are ok except for ACOK which is about 9.5v ???) but, sometimes, it stops recognizing the battery and must be disconnected and reconnected (problem described from the customer for the other pc).

The new ic i had ordered from another seller should arrive in these days.... I'll let you know

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Tiger (TI FAE) has posted full details on the above linked TI support forum.

1) Inspect the cap on the REGN pin. It is required and is critical.

2) Remove all power and confirm that both ACFET & RBFETs are not defective.

3) Once ACDET is confirmed to be > 2v4, Vcc to the charger IC is high enough (19v), REGN will turn ON to supply 6 volts higher than CMSRC to the gates of the n-channel mosfets. CMSRC is zero at the start of this cycle.

Then ACFET will turn ON and since the gates are common for the first 2 mosfets, so will the RBFET and the AC adapter voltage will reach B+.

Confirm that the current sense legs of the B+ rail are properly reaching the charger IC so that the charger IC does not feel there is a need to shut down this process which appears to be the case for your logic board.

Confirm the resistance from each leg of the current sense resistor back to the charger IC. A wrong value will fool the charger into believing there is too much load so the mosfets should be shut off.

Do review the TI forum thread for a proper explanation from Tiger.

Continue to post your updates. This is a very good topic to assist in future repairs.

Update - from a quick review of your last post - replace the RBFET (ie. 2nd mosfet that links to the B+ rail). Confirm the cap on REGN is a good capacitance - replace it if you have another cap that is 2.2uf or higher (6 volt or higher rating).

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Have posted a thread on the TI forum which you can follow here:

https://e2e.ti.com/support/power-man...acdrv-question

Thank you very much for your time, i'll check the discussion to see if anyone can give us other important information (now there is an answer but it's not very useful).

1) Do you have a stable REGN (+6 volts) on your charger IC @ PU1 ?
2) Any corrosion on this board and area of the logic board ?
3) Confirm the current sense parts and traces are reaching the charger IC ok.
4) For the brief 1-2 seconds where ACOK is pulled high -> what voltage is present @ B+ ?
5) Remove all power and review the resistance across each mosfet pin to confirm the mosfet is not defective.

1) Regn seems stable at 6v (5,95v) with dc adapter connected. 0v on battery.
2) No corrosion/water damage.
3) Each trace and current sense seems to reach the charger ic.
4) Not always the dc passes the 2nd fet. But in both cases the initial situation is the same. I get about 1v between PQ1 and PQ9054 slowly increasing to about 3v, then:
option 1: the voltage rises rapidly to 12-15v and B+=12-15v, ACOK goes low.
option 2: the voltage decreasing slowly to 0v and B+=0v, ACOK goes low.
5) All measurements result in > 1.5Mohm except for source-drain of pq29 that is 200Kohm slowly increasing to 350Kohm. All fet closes correctly to 0ohm if tested with 2 testers in diode/beep mode.

Not true since ACOK can be pulled up to an external supply derived from the main power rail. So it may not be high before the DC-in MOSFETs are turned on, but it's not necessarily pulled low by the charger IC either.

In this board ACOK is pulled up by a voltage divider connected to REGN. Then a trace reach the EC.
Until the EC is not powered there is 0.7v on ACOK, when the EC is powered there is more or less 3.1v.
I'm sure that the signal is pulled low by the charger ic for 2 reasons:
1) only the charger ic is powered when the dc don't reach the B+ rail.
2) i tried to cut the trace between the EC and the voltage divider, and the signal goes from 3v to 0v at the same time.

As far as I understand it, ACDRV bootstraps at ~6V to turn on reverse protection MOSFET while there's still 0V on source (also 0V on CMSRC), which causes it to start turning on and have current flowing through it, increasing voltage on CMSRC which in turns increases voltage on ACDRV (which should stay 6V above CMSRC), until it's fully turned on and ACDRV reaches DC-in voltage + 6V.
As indicated in datasheet, if DC-in MOSFETs Vgs < 5.7V for more than 20ms is a fault condition. You'd need an oscilloscope to observe that as most multimeters won't catch it.

In any case there shouldn't be a need to go to such length as https://www.badcaps.net/forum/showthread.php?t=90356 covers almost all cases.
One thing that's not covered is that a bad contact in DC-in jack can also cause a voltage drop due to higher current draw when turning on DC-in MOSFETs which will create a fault condition (voltage drops below UVLO) and the multimeter may not catch it either. Bad DC-in jack can also disable charging circuit on some machines.
Another is a bad buck converter MOSFET for battery charging rail that can pull REGN low.

I had already read your "bible" about the charger ic, i found lots of useful tips in the past (and this is an opportunity to say thank you very much for it) but i don't find nothing helpful for this case. The DC connector is broken, i use 2 wire soldered in the board, so i can exclude this thing.
The ACDRV bootstrap is an interesting thing that i didn't know. I have an old oscilloscope or a newer (but cheaper and chinese) one, but i was unable to take the moment. I tried with the tester to do some tests (attached). However, the problem always seems to be linked to the too-slow rise of the voltage on B+. If it really works with a "bootstrap" by the +6v REGN the problem may also be due to the faulty bq24780s (already replaced several times) or to the 2.2uf capacitor on pin 24, that i have now tried to replace but without result.

I'm starting to think that in the fall of the notebook there is the board damaged somewhere and it creates problems in the "24780 startup"...

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Have posted a thread on the TI forum which you can follow here:

https://e2e.ti.com/support/power-man...acdrv-question

[piernov]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

but without ACOK there will be no ACDRV.

Not true since ACOK can be pulled up to an external supply derived from the main power rail. So it may not be high before the DC-in MOSFETs are turned on, but it's not necessarily pulled low by the charger IC either.

Without CMSRC there will be no ACDRV.

As far as I understand it, ACDRV bootstraps at ~6V to turn on reverse protection MOSFET while there's still 0V on source (also 0V on CMSRC), which causes it to start turning on and have current flowing through it, increasing voltage on CMSRC which in turns increases voltage on ACDRV (which should stay 6V above CMSRC), until it's fully turned on and ACDRV reaches DC-in voltage + 6V.
As indicated in datasheet, if DC-in MOSFETs Vgs < 5.7V for more than 20ms is a fault condition. You'd need an oscilloscope to observe that as most multimeters won't catch it.

In any case there shouldn't be a need to go to such length as https://www.badcaps.net/forum/showthread.php?t=90356 covers almost all cases.
One thing that's not covered is that a bad contact in DC-in jack can also cause a voltage drop due to higher current draw when turning on DC-in MOSFETs which will create a fault condition (voltage drops below UVLO) and the multimeter may not catch it either. Bad DC-in jack can also disable charging circuit on some machines.
Another is a bad buck converter MOSFET for battery charging rail that can pull REGN low.

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Hi.

1) Do you have a stable REGN (+6 volts) on your charger IC @ PU1 ?

2) Any corrosion on this board and area of the logic board ?

3) Confirm the current sense parts and traces are reaching the charger IC ok.

4) For the brief 1-2 seconds where ACOK is pulled high -> what voltage is present @ B+ ?

5) Remove all power and review the resistance across each mosfet pin to confirm the mosfet is not defective.

Each mosfet linked to this charger IC should be reviewed.

With no power, meter in resistance mode, check:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post the readings for:

PQ1 (ACFET)
PQ9054 (RBFET)

PQ30 (HIGH SIDE battery charge FET)
PQ29 (LOW SIDE battery charge FET)

PQ2 (Battery FET)

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

TBH - found the same issue to be a puzzle - which comes first ?? The chicken or the egg ? The TI documentation is written in a format that only twins can understand.

The following thread is a must read - the 3rd from bottom reply from wang5577 explains it well:

https://e2e.ti.com/support/power-man...-don-t-turn-on

Thank you for your reply and for sharing this link. I read lots of thread in TI's forum, but not this. The situation is similar, and also in my board i can enable ACDRV only if inject 19v on CMSRC.
Probably in my board the bq24780 realizes that something is not correct, so it sets ACOK to 0v and removes +6v of the regn from the ACDRV (probably can't bring ACDRV to 0v if CMSRC remains active), so this brings about 16v in the B+ rail, and without ACOK the battery is not charged.

I believe that in the circuit of Martin Andersson70 (of your link) the problem comes instead from the too low voltage which leads the 24780 to suspect an excessive absorption / short circuit.
After its modification, ACDRV remains active, but note that a higher voltage is supplied to CMSRC than the input voltage of the N5800 mosfet, therefore the mosfet could be fully close even without +6v of the REGN and probably the bq24780 realizes that there was no short circuit / excessive current draw since after the fet there is the right voltage without any delay.

The solution of my problem is probably in the "SELECTOR LOGIC" indicated in the attached image (taken from the datasheet). Without knowing its operating logic it's difficult to understand where is the problem, since all the components look good and/or have been already replaced.

Unfortunately i'm not an expert on these ICs. An attempt could be to cheat the current draw control, but.. how??

AFAIK,ACDET must be in range, CMSRC must be 19V along with LDO being present are the 3 pre-requisite for ACDRV to work on BQ24780S.

Thank you too for your reply. All requirements are present, but without ACOK there will be no ACDRV. Without ACDRV there will be no CMSRC. Without CMSRC there will be no ACDRV. Without ACDRV there will be no ACOK, and so on..
A IT engineer is required to explain us the operating logic of BQ battery chargers

sir if charging ic is not working, can the board be power-on?

Yes, sometimes it can be simply bypassed if the IC does not create problems of excessive current draw or short circuit. Sometimes, especially if it has to be removed, it's necessary to modify some signal for the EC to make the pc turn on.
If the IC is broken, the battery will be unusable. Only in cases similar to mine can the battery be used (but, obviously, cannot be recharged)

[usyusy]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

AFAIK,ACDET must be in range, CMSRC must be 19V along with LDO being present are the 3 pre-requisite for ACDRV to work on BQ24780S.

sir if charging ic is not working, can the board be power-on?

[mcplslg123]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

AFAIK,ACDET must be in range, CMSRC must be 19V along with LDO being present are the 3 pre-requisite for ACDRV to work on BQ24780S.

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

TBH - found the same issue to be a puzzle - which comes first ?? The chicken or the egg ? The TI documentation is written in a format that only twins can understand.

The following thread is a must read - the 3rd from bottom reply from wang5577 explains it well:

https://e2e.ti.com/support/power-man...-don-t-turn-on

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

the customer left me the notebook and doesn't want it back. I am continuing the repair when i have some free time, and there are some updates:

I replaced all ACN/ACP and SRP/SRN capacitors with same value and PC1 with 2200pf and PC2 with 0,1uf. Now i get about 12-15v on B+ rail with this situation:

on dc:
PQ1 GATE 12-17v
PQ1 SOURCE 12-15v
PQ1 DRAIN 19,5v

PQ9054 GATE 12-17v
PQ9054 SOURCE 12-15v
PQ9054 DRAIN 12-15v

PQ2 GATE 11,35v
PQ2 SOURCE 11,35v
PQ2 DRAIN 12-15v

nothing is hot, orange charging led on, there is a constant buzzing and intermittent ticking, power on but when current drawing is high than 0,7-0,8A it shut down.


on battery:
PQ1 GATE 0v
PQ1 SOURCE 0v
PQ1 DRAIN 0v

PQ9054 GATE 0v
PQ9054 SOURCE 0v
PQ9054 DRAIN 11,35v

PQ2 GATE 17,30v
PQ2 SOURCE 11,35v
PQ2 DRAIN 11,35v

nothing is hot, orange charging led off, no strange noise, boot ok.


EDIT:
I still don't understand how the ACDRV works. more precisely i don't understand how/when the bq24780 decides when to activate the first mosfet..
Is it opened by the bq24780 after the CMSRC is present or is it opened by the bq24780 when VCC is present and (only after this) the bq24780 check if the voltage passes from the mosfet through the CMSRC??

This would be crucial to understand why the fet is not closed correctly. Can any expert explain this to me?
Hope you can understand even if my english is not good

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

a few days ago i casually read this post on the forum: https://www.badcaps.net/forum/showpo...81&postcount=6
so i tried to connect a 4k resistor from 19v to CMSRC (pin3). in this way ACDRV remains active (but is 19v instead of 25) and ACOK is 3.3v for about 2 seconds, then it returns 0v.
could the problem be around PC1 and PC2? I tried to replace them with the same value but nothing has changed.. maybe you or someone experienced with 24780 know some tricks

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Ok. Remove the high side resistor on ACDET that is fed by the adapter input.

Then ACDET should see < 17v, to be exact it should be 0V since you have removed this connection.

Then confirm the voltage of ACOK.

With ACDET 0v also ACOK is 0v. With 0,7 < acdet < 2,4 the ACOK is high. but still no ACDRV.

Other "dangerous" tests..
1) 19v on VA and 19v in +VIN i get for about a second ACOK 3,5v and VA2 15,5v

2) 19v on VA (ACOK 0v), then 19v in PQ1/PQ9054 gates i get for about a second ACOK 3,5v and VA2 16v, +VIN 16v (VA2 and VIN stay 16v until i remove 19v on gates)

3) replaced PQ1/PQ9054 -> same situation, identical voltage values

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

Ok. Remove the high side resistor on ACDET that is fed by the adapter input.

Then ACDET should see < 17v, to be exact it should be 0V since you have removed this connection.

Then confirm the voltage of ACOK.

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

ACOK is floating when DC IN is < 17, and 6v REGN is present. So, if i reconnect the cutted trace from pin 5 ACOK to the voltage divider (and the ACIN in the EC) i read about 0.7v. This value is only if the EC is not powered. When the EC is powered i read about 2.9v in ACIN/ACOK.
If the DC IN increase to 18 or 19v (>17v) the ACDET is > 2,4v and the ACOK is pulled down from the 24780s after some msec.
I need to completely remove the power to get ACOK floating again. Decreasing the DCIN doesn't do the trick.

[mon2]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

When DC IN is < 17v, what is the voltage on ACOK ?

That is, does the charger enable the 6 volt LDO REGN and allow for ACOK to be ~3v (due to the resistor based voltage divider on ACOK leg for about 50% of REGN voltage) ?

[vannix]

Re: Acer A315-55G / DA0ZAWMB8E0 not charging

There is no short to ground on any coil. Only pl7002 is 25ohm (but is connected to vccsa to cpu). I inject 19v on +VIN and the board draw about 20mA.
Shorting pin 1 and 2 on keyboard connector (power switch) the board start normally (draw from 0.4 to 1.1A). I didn't conncect the lcd but seeing the amp drawing in the meter i'm pretty sure that it booted normally.

The problem is in the charging circuit, well hidden