820-3437-B not turning on.

[BCN_Techs]

Hi,

Got this board with water damage U1900 and ISL area.

U1900 was replaced and now i get PVRTC_G3H 3,42V.

ISL also was replaced. Magsafe has light.


Now have this reails:

PPBUS is ok

ALL S5 and S4 reails are ok, except PP3V3_SUS and PP5V_S4RS3 ( It's generated from U8050 that doesnt recieve SMC_SENSOR_PWR_EN, it's just pulsing from 0 to 3.4 every 2-3 seconds.V)

Do you think it's SMC ?


P.S: SOrry. PP3V3_SUS is present and all sys pwr is pulsing every 2-3 seconds.

Already checked u1900 again and it seems be ok.

Also checked SMC bypass and fan spins for half second and stops.

 

[2informaticos]

PP3V3_SUS is required to generate PM_RSMRST_L signal.
Are you sure measured correctly???

Post all classic signals involved in Power On Sequence.
Also try to start in SMC bypass mode.

 

[BCN_Techs]

Thanks informaticos. Had just edited my post right when u was writting.

 

[2informaticos]

Both pins 7 & 3 of U1950 pulse?
Do you note pulsing VCORE too?
Get correct 32KHz from U1900?
AVREF_SMC is OK?

Check all SPI Bus Series Termination resistors.
Finally, try new BIOS.

 

[BCN_Techs]

Pin 7 and 3 pulsing.
Vcore pulsing too. Getting 32Khz from 1900 and AVREF_SMC 3.3V .

SPI resistors seems be ok. About BIOS already tried a couple extracted from same motherboard and 2 that are bought new ( from my usual supplier that have sent many working efis) and it stucks.

Also noticed that VSUS appears after 20-30 seconds when magsafe is connected.

 

[BCN_Techs]

SOLVED: INformaticos was right ( like always). R6102 was fucked. thank you