Acer A715-75G NO POWER

[madjid911]

hello, i have an Acer A715-75G FH5VF LA-J861P laptop that won't start, 19V ok 5V ok but no 3V, enable2 (ENLDO_3V5V) 4V5, enable1 0V, can you help me please , I am not an expert, I looked at all the resistors and short-circuit nothing seems abnormal to me.

I changed the 3V chip (SY8288BRAC) three times but no result, it is well supplied with 19V5 but does not trigger the 3v

I attach the diagram for those who need it

Thank you for your help

(my english is basic sorry)

[reformatt]

Re: Acer A715-75G NO POWER

+3VLP (pin 17) voltage? You have an enable for it, so you should get +3V. This powers the EC, which I'm assuming must be working in some fashion to get +5VALWP.

Check MAINPWON and 3V_EN_R. 3V_EN must be high to get +3VALWP.

[madjid911]

Re: Acer A715-75G NO POWER

+3VLP (pin 17) voltage? You have an enable for it, so you should get +3V. This powers the EC, which I'm assuming must be working in some fashion to get +5VALWP.

Check MAINPWON and 3V_EN_R. 3V_EN must be high to get +3VALWP.

MAINPWON 3V26
3V_EN_R 0V (RB15 1MOHMS, RB14 1Kohms its ok)
DB1 mode diode 0V305 ans 0V its ok
+3VLP (pin 17) 3V27V
ENLDO_3V5V 4V5 its too high? or normal ? PR301 PR302 and pr301 its ok.

Thanks

[reformatt]

Re: Acer A715-75G NO POWER

All good so far. Review your power sequence diagram on Pg 5 of the schematic. You will only get +3VALWP after power button on/off.

Check the power button for +3V and confirm it drops to 0V when pressed. Then confirm whether you have 3V_EN_R go high from the EC.

[madjid911]

Re: Acer A715-75G NO POWER

All good so far. Review your power sequence diagram on Pg 5 of the schematic. You will only get +3VALWP after power button on/off.

Check the power button for +3V and confirm it drops to 0V when pressed. Then confirm whether you have 3V_EN_R go high from the EC.

Hello, yes I had not seen this page 5, now that I press the power button, the laptop starts and restarts constantly, the 3 v is triggered and remains constant.

before, the chipset was shorted, I changed it and reballed a new one bought on ali express, maybe the soldering is not good I don't know if I received a chipset with lead-free off or with lead so I heated between the two.

Do you think the chipset is married?

Thanks

[madjid911]

Re: Acer A715-75G NO POWER

Hello, yes I had not seen this page 5, now that I press the power button, the laptop starts and restarts constantly, the 3 v is triggered and remains constant.

before, the chipset was shorted, I changed it and reballed a new one bought on ali express, maybe the soldering is not good I don't know if I received a chipset with lead-free off or with lead so I heated between the two.

Do you think the chipset is married?

Thanks

I heated the new stronger chipset, now it works, thanks for your help

[reformatt]

Re: Acer A715-75G NO POWER

Do I understand you replaced the PCH? No mention of that in your first post.

If that is what you've done, then you will also need to clean your ME in the BIOS.

[madjid911]

Re: Acer A715-75G NO POWER

Do I understand you replaced the PCH? No mention of that in your first post.

If that is what you've done, then you will also need to clean your ME in the BIOS.

Yes I had replaced it because it was shorted which had burned the 3v chip