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

[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

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

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

[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)

[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

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

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

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

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

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

[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

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

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

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

[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

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

[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

[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.

[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?

[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)