Hello,

this board came with a strange symptoms, sometimes it starts and sometimes it doesn't

with a quick check I've found that there's 3.3v and 5v LDO, after the button is pressed there is 2.2v on PL23 and 4.1v on PL20 with no start ofcurse.. resistances are PL23 = 103 ohms, PL20=16.7 Kohms

immediately replaced PU3 RT8223, (PQ51 & PQ26) was AO4496 and (PQ46 & PQ21) was AO4712 (all replaced), the power rails went normal for a one successful start then went sagging again..

checked the values of all the resistors around PU3 and no abnormal values was found, and while measuring FB pins pin2 & pin5 while the power was connected I heard clicking on the board and PU3 start boiling, disconnected the power and a short was found on LDO3 leading to a dead KBC !

could it really be killed by measuring the feedback voltages ?

anyway, the KBC was replaced from a donor quanta R13 board, there's 3.3v and 5v LDO, and 3.3v on the power button but there is no reaction to the button now, there is no S5_ON signal coming to PU3...

where to dig and what could cause the sag of the 3v/5v power rails ?

EDIT: reaction to power button restored, dead hall-sensor found and LID_EC# restored, still 2.2v/4.1v

Всё возможно, но если я не ошибаюсь, то Вам нужно прошить мультиконтроллер (KBC), и всё же стоит распаять пост карту что бы было прощё понимать что сейчас не так.)

thanks for the reply, the KBC in this platform pulls it's firmware from external chip "U13"..

I've found it !

removed PL20 & PL23, using the LBP I've injected +3v through the lines, PL20 consumed 0.05a something, while PL23 (was 103ohms) suddenly pulled +3Amps and growing ! disconnected the LBP and measured the line again and it is 2.3ohms now !

Injected +3v to the line and searched for heat only to find out that the solid capacitor PC223 was barely hot, replaced it and +3v/+5v appeared correctly and the board started

Topic closed