820 3437 then spin , then stop .

[funtotos]

Hi all

I've got a 820-3437. When I connect the magsafe the fan spins then stops, then spins then stops but no start.
green light on charger :

pp5v_s5 ok
PP3V3_S5 ok
PPVRTC_G3H ok

no P5VS4RS3_EN
no PM_SLP_S5_L
no SMC_S4_WAKESRC_EN
no S4_PWR_EN
no PM_SLP_S4_L

no short

any ideas ?

 

[JohnB8812]

Resistance between pins 17/18 and 27/28 of the ISL6259? Any history liquid etc?

 

[2informaticos]

Toooooooooooooo many "no" there.
Imposible, if the fan spins...
So check if all coils get pulse at least.
ALL_SYS_PWRGD pulse too?

Catch the voltages when the fan spins, of course.

 

[funtotos]

when the fan spins
ALL_SYS_PWRGD : 3.35v 2 second

I don't know the history

thks

 

[2informaticos]

Any pulse at CPU coils too?
Check for pulses at U1950, pins 7 & 3.

 

[funtotos]

u1950 pin 7 and 3 = 3.43v (fan spin)

When i connect the magsafe the first time , no boot (green light and orange )
When i connect the second time , the fan turns then stop (green light and orange )

 

[2informaticos]

Check if all voltages from page 58 appear.
Yopu should get CPU voltage too.

Start removing SSD, this can generate strange issues if bad...
Also start without flex connected between MLB and LIO board.

 

[Paul Daniels]

Check that you're getting PPRTC_G3H at the rest of the board, not just on C1910