Please Help Identify Missing BIOS Voltage

[sparrow2719]

Hi I have an acer e5 471 with no voltage on bios, their vcc line pin 8 is missing 3.3V.

Based on the block diagram i have, the voltage +3V_PCH_ME for bios voltage is coming from +3V_S5 (pic 3).

+3V_S5 is coming from AO3404. A3404 is getting power from +3VPCU. (Pic 2).

The one thing confused me is the PCH is also has a +3V_S5 and so on. (Pic 1).

Is this PCH is distributing out the voltage too or it is an input voltage for PCH ?

[khaahk]

Re: Please Help Identify Missing BIOS Voltage

You will get +3V_S5 (also on bios chip) when EC gives S5_ON control signal to AO3404. If you have high level on S5_ON then check the transistor, if not then check if EC has power.
3V is input for PCH.
Check PU3 output voltages 5v and 3v and 15v.

[sparrow2719]

Re: Please Help Identify Missing BIOS Voltage

You will get +3V_S5 (also on bios chip) when EC gives S5_ON control signal to AO3404. If you have high level on S5_ON then check the transistor, if not then check if EC has power.
3V is input for PCH.
Check PU3 output voltages 5v and 3v and 15v.

Noted, thanks for the info.
It turns out the AO3404 bad, replaced and solved.
Thank you.

[Crypts]

hello Friends..
can you help me where i can find the circuit AO3404 in motherboard for testing and changed

[Crypts]

schematic board..
https://www.badcaps.net/forum/troubl...ta-zaar-rev-3a