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Old 06-30-2013, 11:30 PM   #1
lezsimply
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Default Acer Aspire E1-571 no power

Good day to everyone. I hope you guys can help me regarding this acer laptop. This just came in yesterday, the owner said it has no power and no blinking lights. I've tested the power adapter and it is perfectly working. I did disassembled it and found horrible images of a repair done by someone who is not careful.

To fix the problem, I tried to look for a schematic diagram of its motherboard over the net but I'm very unlucky and cannot seem to find one. I figured that someone here might have copy or something that could help me fix it.

Here's the exact model of the laptop: Acer Aspire E1-571-32324G32MNKS and also this is printed on the motherboard itself: Q5WVH LA-7912P Rev 1.0 2012-03-22. Hope to hear from you guys. Thanks very much in advance!

I think somewhere here could be the fault:
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File Type: jpg Bottom.jpg (719.8 KB, 1205 views)
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Old 06-30-2013, 11:54 PM   #2
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Default Re: Acer Aspire E1-571 no power

Could be a shorted MOSFET near the coils.

Anyway, here's the schematic that is closest to what you are looking for.
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Old 07-01-2013, 02:05 AM   #3
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Default Re: Acer Aspire E1-571 no power

Thanks for the reply sir. It seems that the schematic is somewhat similar to my current board because of the values. PQ9 outputs 19.4v while PQ10 has no output no reading at all. what other component I need to check before I take the fet out. Some capacitors has no labels on it. I appreciate your help sir. A big thanks again.

Last edited by lezsimply; 07-01-2013 at 02:06 AM..
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Old 07-01-2013, 10:06 AM   #4
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Default Re: Acer Aspire E1-571 no power

After I few cleaning and resoldering. I manage to power up the laptop. I can now boot to windows. I've been testing this unit for almost 5 hours now and nothing seems to be wrong. There are 2 things that I noticed during the test period, the battery indicator on the laptop keeps blinking amber light continuously and on the system tray icon, power says 34% plugged in but not charging. I think the charging circuitry still has some fault on it. Tomorrow I'll be disassembling the laptop again to review the components. I'll post whatever I may find. Thanks again!
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Old 07-02-2013, 10:40 AM   #5
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Default Re: Acer Aspire E1-571 no power

Guys I need some help again, could somebody please help me identify which pin of PU4 (BQ24725ARGRR) gives voltage to charge the battery. I've been reading the datasheet and can't identify which pin that gives charge. The battery is detected but still does not charge. I can power the laptop using the adapter. The battery is confirmed working. Hope someone could help thanks!

here's the exact image of the motherboard:
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Old 07-02-2013, 06:59 PM   #6
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Default Re: Acer Aspire E1-571 no power

Here's the data sheet bro, pin descriptions are on page 12-13.
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File Type: pdf bq 24725.pdf (1.47 MB, 1717 views)
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Old 07-03-2013, 04:16 AM   #7
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Default Re: Acer Aspire E1-571 no power

Thanks Sir whaldsz, I've already downloaded your datasheet. After reading the Pin functions, I got a little confuse is it pin no. 11 or pin 12? Sorry for being dumb. By the way I noticed we're from the same country Thanks again.

Last edited by lezsimply; 07-03-2013 at 04:18 AM..
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Old 07-03-2013, 05:15 AM   #8
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Default Re: Acer Aspire E1-571 no power

what is your question about pin 11 or 12 bro?
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Old 07-03-2013, 07:35 AM   #9
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Default Re: Acer Aspire E1-571 no power

Which of those pin gives charge to the battery. The reason why I ask is because the battery isn't charging when connected to laptop. tray icon shows how much battery left but also indicates that it is not charging. I figure that the previous person who attempted to fix the motherboard might have damage some components which cause the battery not to charge.
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Old 07-03-2013, 09:16 AM   #10
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Default Re: Acer Aspire E1-571 no power

none. pin 11 drives the gate of the mosfet PQ11 to give B+.

pin 10 (ILIM) is the one responsible for charging the battery. Voltage should be above 105mV to enable charging.
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Old 07-04-2013, 10:34 AM   #11
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Default Re: Acer Aspire E1-571 no power

Sorry for late reply, if I follow the path of pin 10 (ILIM), I would possibly find the fault? There are 3 more components connected to it. 2 resistors and a capacitor.

I've been looking at the battery circuitry so many times and just this now, I realize that I think something might be missing. As you can see at the image below (CIRCLED IN RED) it seems that a capacitor had been peeled off this spot. Its really hard to tell because there's no label on the board. I'll try to search the net for a good image of the motherboard and see if I can magnify it for comparison. I'll keep you posted. Thanks again for the big help!
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Old 07-04-2013, 11:19 AM   #12
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Default Re: Acer Aspire E1-571 no power

did you remove the rtc battery for a while and put it back. If the protection circuit is in the errror state may couse the problem.
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Old 07-04-2013, 11:59 AM   #13
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Default Re: Acer Aspire E1-571 no power

Hi Spidey. Honestly, during the cleaning and resoldering process I forget to remove the battery does it have any effect on it?

After searching the net for over an hour, I finally found an image of the motherboard closest to mine. We have the same board model. He is also missing some component but different than mine. I have attached the 2 image, mine is the one with yellow and red circle. On the other image I marked the component I'm missing circled in orange. Please help me confirm this thanks!
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File Type: jpg Top Portion PU4.jpg (891.0 KB, 479 views)
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Old 07-04-2013, 07:08 PM   #14
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Default Re: Acer Aspire E1-571 no power

Try to measure the voltage at pin 10 and observe the voltage if it is rising or falling. It should enable charging of your battery when the voltage exceeds 105mV.

Also, the resistors you mentioned is a voltage divider circuit. whatever the exact voltage of your +3VALW (which is typically 3.3V), you should have +3VALW * 100K/(100K+316K) = 79mV at that pin.

If PR61 (100k ohms) resistance becomes lower than 100k ohms or PR58 (316K ohms) becomes higher than 316k ohms, then pin 10 will never become higher than 105mV. This is one logical explanation why the battery would not charge.

Of course there are other components that may contribute/cause this problem - battery not charging. But to cover all cases, please refer to the datasheet on page 22 or see attachment, you can read the conditions when charging is enabled or disabled.
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Old 07-06-2013, 02:47 AM   #15
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Default Re: Acer Aspire E1-571 no power

Good day. I measured pin number 10 of PU4 and I got .82v on the meter. 3.34v is present. At PJP2 pin no. 1 and 2 to has no output. I also placed a cap on the location that I think its missing one. Please refer to the attached image. Battery still not charging. thanks again.
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Old 07-06-2013, 08:01 AM   #16
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Default Re: Acer Aspire E1-571 no power

Do you get 19v at P2? Is ACOK pin high?

.82V indicates the state is not charging. This could mean the one of the resistors has changed value.
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Old 07-06-2013, 10:31 PM   #17
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Default Re: Acer Aspire E1-571 no power

After days of exhaustion, I've managed to solve the problem. The battery is now charging This is made possible because of Sir whaldsz effort to help me. Thanks again sir

I cannot point to what component really is at fault because I have replaced 3 components, (PQ11) and two resistors on Pin #10 of PU4 that Sir whaldsz mentioned. I also reflowed IC PU4. So I guess 1 of those might have fix it. And also I kept reading reply #14 of Sir whaldsz and the attachment he included. Understanding it is very hard for me considering I have no idea how to read schematics and don't know how to identify components.

Again Thanks a lot for the help Sir. And more power to badcaps.net
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Old 07-07-2013, 12:41 AM   #18
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Default Re: Acer Aspire E1-571 no power

glad to be of help
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Old 11-13-2013, 02:40 AM   #19
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Default Re: Acer Aspire E1-571 no power

Hi !

I have problem with Acer E1 - 531. It has Q5WVH LA-7912P motherboard. First problem was AC adapter died and it's replaced under waranty. Several months later motherboard died but warranty terminated just before that

I have found PQ10 shorted. It's AO4466L. I have tried to put FDS6294 instead of it. After change i powered it up on AC without battery. It was working for about 15-20 seconds and died again. Something else must be wrong now, because PQ10 seems OK. On PU4 (BQ24725) Vcc is OK, ACDET is OK (cca 2.5V stable), REGN is OK (6V stable) but ACOK is going up and down and B+ (P2) are rising and falling in same way. What can i try next ? I need help ...
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Old 11-13-2013, 06:39 AM   #20
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Default Re: Acer Aspire E1-571 no power

I usually replace the component of the same kind, but I think it's close enough. Have you checked pc25 and pc16? try to check pc31 and pd6 also.
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