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Old 07-03-2020, 07:05 AM   #1
Mulong2019
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Default acer aspire 4752

Anyone can help me on this acer aspire 4752 JE40 HR MB 10267-4. the problem is all voltages are present but cannot power on, i notice that if i touch the pin 4
ON PWRCN1 3.3v bluelight comes if i remove blue light gone, and also notice the mosfet connected to same with pin 4, pin 4 have 3.3v pin3 have 3.3v
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Old 07-03-2020, 08:42 AM   #2
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Default Re: acer aspire 4752

anyone please help
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Old 07-03-2020, 09:20 AM   #3
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Default Re: acer aspire 4752

bad solder joints may be the cause does the voltage drops #power button ?
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Old 07-03-2020, 09:17 PM   #4
Mulong2019
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Default Re: acer aspire 4752

the voltages is not droping it stays on 3.4v but goes up on .42 to up something.I noticed also that when i rest the board for a couple of minutes it can turn on directly with no problem but unplugging and plugging back the charger it cannot turn on but voltages on pin 4 is ok
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Old 07-03-2020, 11:34 PM   #5
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Default Re: acer aspire 4752

try to re solder it...try to test continuity..
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Old 07-04-2020, 01:49 AM   #6
Mulong2019
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Default Re: acer aspire 4752

already did resolder same results I noticed once it cannot turn when you touch the 3pin mosfet 1 and 3 turn on lights blue comes up but when release lights gone
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Old 07-04-2020, 02:25 AM   #7
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Default Re: acer aspire 4752

Quote:
Originally Posted by Mulong2019 View Post
already did resolder same results I noticed once it cannot turn when you touch the 3pin mosfet 1 and 3 turn on lights blue comes up but when release lights gone
heat the MB with hot air gun near charging IC & 3&5V regulate & the first 2 fets for any results
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Old 07-04-2020, 02:29 AM   #8
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Default Re: acer aspire 4752

Quote:
Originally Posted by Mulong2019 View Post
already did resolder same results I noticed once it cannot turn when you touch the 3pin mosfet 1 and 3 turn on lights blue comes up but when release lights gone
here is the schematics try to trace it..
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Old 07-04-2020, 04:00 AM   #9
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Default Re: acer aspire 4752

@techtiger i tried your idea reheat the chip and mosfet still the same it turns on when laptop is on rest but after plugging out and plugged in again cannot turn on
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Old 07-04-2020, 05:52 AM   #10
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Default Re: acer aspire 4752

Quote:
Originally Posted by Mulong2019 View Post
Anyone can help me on this acer aspire 4752 JE40 HR MB 10267-4. the problem is all voltages are present but cannot power on, i notice that if i touch the pin 4
ON PWRCN1 3.3v bluelight comes if i remove blue light gone, and also notice the mosfet connected to same with pin 4, pin 4 have 3.3v pin3 have 3.3v
did you check the ram if its ok... did you reflash the bios? all voltage rails are present? try to reflash the bios chip.. try also to check the rtc bios battery.. is the switch button connected to the keyboard? if so try to disconnect the keyboard and connect the power adapter if it still powers on..

here is the bios dump
https://www.badcaps.net/forum/attach...4&d=1464192697

Last edited by Duranitron; 07-04-2020 at 06:23 AM..
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Old 07-04-2020, 06:22 AM   #11
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Default Re: acer aspire 4752

JE40 HR boardview - https://www.badcaps.net/forum/showthread.php?p=972108
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Old 07-04-2020, 06:56 AM   #12
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Default Re: acer aspire 4752

@duranitron ram is ok because once it turns on display comes and you can used no problem, once you unplugged the charger and plugged again it cannot turn on, I need to wait for a couple of minutes to turn again, all voltages are present, i did not try to flash the bios
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Old 07-04-2020, 08:42 AM   #13
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Default Re: acer aspire 4752

tried flashing the bios same result
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Old 07-04-2020, 09:48 AM   #14
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Default Re: acer aspire 4752

is the fet pu3802 ? when you touch BLUE light comes on
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Old 07-04-2020, 08:10 PM   #15
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Default Re: acer aspire 4752

@techtiger the mosfet is Q6801 Which touching it bluelight comes but fan is not spinning
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Old 07-05-2020, 02:58 AM   #16
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Default Re: acer aspire 4752

anyone can help on this please
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Old 07-05-2020, 03:03 AM   #17
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Default Re: acer aspire 4752

Remove the ribbon cable from PWRCN1, short pin 3 to GND, see if the board powers up.
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Old 07-05-2020, 03:35 AM   #18
Mulong2019
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Default Re: acer aspire 4752

@smdflea already tried that nothing happens but if i short this 3pin mosfet blue light comes up fan not spinning but release it blue light gone
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Old 07-05-2020, 03:53 AM   #19
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Default Re: acer aspire 4752

Its only for the LED if you think its a problem remove or replace the mosfet. With no power check theres no continuity between PWRCN1 pins 3 and 4.

Last edited by SMDFlea; 07-05-2020 at 03:57 AM..
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Old 07-05-2020, 07:57 PM   #20
Mulong2019
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Default Re: acer aspire 4752

I tried replacing that mosfet still the same issue
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