LA-7912p Power proble, need power sequence.

[nazrul145]

Hello, I have problem with acer E1-571 power problem,
its +3valw and +5Valw ok but no power. RSM_RST# not found.
please help. U42 Pin 8 +3vs miss.

[nazrul145]

Re: LA-7912p Power proble, need power sequence.

Hello, I have problem with acer E1-571 power problem,
its +3valw and +5Valw ok but no power. RSM_RST# not found.
please help. U42 Pin 8 +3vs miss.

[dellxps15]

Re: LA-7912p Power proble, need power sequence.

report u36 pin 8 volt and u21 all pins voltage.

[nazrul145]

Re: LA-7912p Power proble, need power sequence.

Thanks brother for reply.
U36 Pin8 0V, U21 Pin5678=3.3V pin123=0V and pin4 also 0v.

[dellxps15]

Re: LA-7912p Power proble, need power sequence.

check voltage on R368 both side. if u have 19v in and 0 volt out, check without power supply for short on that side. if no short, replace that resistor.

[nazrul145]

Re: LA-7912p Power proble, need power sequence.

there is no short r368 and replace transistor, but same +3vs not found. PR368 one side 19v and another 0v.

[dellxps15]

Re: LA-7912p Power proble, need power sequence.

have u replaced r368 (resistor not transistor) as i said ?

it's a 47k 0402 5% resistor.

[nazrul145]

Re: LA-7912p Power proble, need power sequence.

i have changed this resistor, but another side is Ov. when i short R368 then q25 transistor burnt. i replace this trasistor also.

[nazrul145]

Re: LA-7912p Power proble, need power sequence.

main problem susp# voltage miss from IO chip.

[dellxps15]

Re: LA-7912p Power proble, need power sequence.

if you remove q25a do u have 19volt both side of r368 ?

as atsio said on other topic # means to be low.

edit: check also c463 if it is shorted.

if not, try remove u21 and measure voltage

[khaahk]

Re: LA-7912p Power proble, need power sequence.

Inspect EC for visual damage.
Does the powerbutton take pin 114 of EC to gnd?
After that does PBTN_OUT# go low for a while?
EC contains its own ROM, so it does not need to read bios at first stage, i think.
When changing KB9012/930 it needs to be programmed.

[nazrul145]

Re: LA-7912p Power proble, need power sequence.

Thanks dellxps15# and Khaahk#. there is no problem q25a and u21. Khaahk yes, powerbutton take pin 114 of EC to gnd. PBTN_OUT# no change. Totally ec have no change when power button change, without ec on/off.
I have change ec with new one but i didnt know this ec needs to programmed.
anyway i give it to customer by shorting q27b pin1 and pin6.
Thanks again.

[khaahk]

Re: LA-7912p Power proble, need power sequence.

Sorry, wrong idea, it has an external EC rom, so at this mb it gets the rom from flash.
But as you got it working, then does not matter...

[dellxps15]

Re: LA-7912p Power proble, need power sequence.

c463 shorted both side ?

[saularciga]

Re: LA-7912p Power proble, need power sequence.

You have to shorting pins 3 and 5 to u12 can work, if no gate voltage of Q25A, will have no voltage drop in the resistor R368

[sachin varghese]

Re: LA-7912p Power proble, need power sequence.

I have a strange prblm with Acer Aspire E1 571 (LA-7912p) when i plug adapter Hdd & dvd Drive working with out trigger.whats the issue ?