820-3435-b not turning on with power button.

[Yoel Ren]

I already used known good sparepart, all sparepart problem can be eliminated FOR sure. ( keyboard, trackpad, trackpad cable, io flex etc )
so when I plug charger, macbook turn on.
but when using only battery, i cant turn it on with powerbutton or even directly shorting smc_onoff_l.
when i tried shorting smc_onoff_l, pm_pwrbtn_l is not bringed down.
shorting pm_pwrbtn_l doesnt turn the macbook on either.

I have tried replaceing :
smc ( 3 times with known good )
u5110

 

[2informaticos]

If you turn off the machine through software, can you turn it on back with power button, with charger connected?
Is the battery properly recognized and charging?

Try to turn it on in SMC bypass also.

 

[Yoel Ren]

if I turn off mac with software, i can turn it on with power button.

its quite difficult to describe the exact symptom, its not consistent.
mac turn on with smc bypass.

 

[Yoel Ren]

this morning , mac's power button works, but a few hours later doesnt work anymore.
when power button doesnt work, mac cant boot with battery connected, but will without battery.

 

[2informaticos]

Check exact resistance between pins 17/18 and 27/28 of ISL6259.
Post CHGR_A/BMON when doesn't want to turn on.

 

[Yoel Ren]

2.8 and 20 ohm.

currently mac still turn on with magsafe, but amon and bmon voltage is around 100mv, is that normal?

 

[Yoel Ren]

with only battery connected, amon and bmon is 0v
if i only use magsafe amon 0v, bmon 0v.
magsafe and battery together, amon 0.7v bmon 0v

 

[2informaticos]

CHGR_A/BMON values depend by current passing through corresponding resistors.
Low values are normal, of course (less than 1V).
Board always turn on correctly in SMC bypass mode?
If yes, there should be another SMC sensor issue.

 

[Yoel Ren]

when power button doesnt work, i cant smc bypass on it.
usually when smc bypass success, fan spin max and the magsafe doesnt light on correct ? but inthis case the fan spin normally and i got magsafe light.

 

[Yoel Ren]

when power button doesnt work, macbook cant boot ( fan spin, but no display )

 

[2informaticos]

Please be clear.
How the machine turns on (fan spins), if power button doesn't work???
Do you mean machine turns on with power button, but not always boot?
Turn on and boot, is not the same thing.

 

[Yoel Ren]

sry, when i say turned on, i mean the fan is spinning, not neccesarily booting.
if power button doesnt work, machine can only be turned on by plugging in magsafe.( turned on mean fan is spinning.)
but mac doesnt boot. after the 3fan cycle, backlight comes for a split of second then no display at all.

sometimes power button work. when it works, mac will boot normally..

 

[2informaticos]

"if I turn off mac with software, i can turn it on with power button."
Even with both charger and battery connected?

Try known good BIOS, just in case.

 

[Yoel Ren]

do you have known good 3435-b bios file ? the one i find forum named 820-3435clean doesnt give me 3 cycle fan spin, looks like something is wrong.

 

[2informaticos]

820-3435 f5n8 clean.bin

drive.google.com

Should work with 3437 bin too.

BTW, I saw several 3435/37 boards working without the classic power cycle.

 

[Yoel Ren]

hmm yeah i for sure seen 3435/37 board without proper fan cycle too, but didnt want to bother with it.
macbook still behave the same btw after bios changed.

 

[2informaticos]

When you've said not working with power button, does it mean the board turns on, but doesn't boot?
Or maybe doesn't turn on at all...

 

[Yoel Ren]

its not consistent, sometimes when power button work, fan still spin, but no display, but sometimes display came.
sometimes using battery will prevent display from coming too. but after I conclude that battery is inhibiting boot, then it works again after a while.
i think its not something to do with image or backlight because it only comes when power button is error.
if this is too much pain in the ass, i would be glad to give it no fix tho, its a headache for me too.

 

[2informaticos]

Heat CPU with quality flux; let see if helps.