820-3437-B ssd not detecting

[PPVCC_S0_CPU]

hi, don't know the history of board as it was bought to use as donor board, but i noticed that 3v3_sus switch was missing, so i replaced it and it started working, but now it doesn't detect ssd.
i have checked voltages to j3700 and SMC_OOB1_R2D_CONN_L is missing. the problem is it comes from u3710, which is AND gate and signal that should be present on its input comes from smc and its missing.
at this point i am out of ideas, can someone provide any solution?

 

[2informaticos]

That is signal data.
You must check power lines and control first.
SSD should be inserted, of course.
Start posting U3740 voltages.

BTW, did you chek a known good SSD?
Start USB OSX and check if Disk Utility sees internal SSD; maybe is not formated...

 

[PPVCC_S0_CPU]

U3740 voltages are fine, except pp3v3ssd_vmon.
as name suggests it should have 3.3 volts but i get around 0.9 volts,(maybe its correct, but i don't have any working board to confirm it)it comes from a voltage divider of r3741(232k) and r3742(100k).


edit: did some maths and i think there should be 2 .2 volts drop across 232k resistor l, so i think u3740 if working fine

 

[PPVCC_S0_CPU]

btw did you chek a known good SSD?
Start USB OSX and check if Disk Utility sees internal SSD; maybe is not formated...

Yeah it came in my mind as well, maybe ssd have high Sierra and board's firmware is not updated to apfs

 

[2informaticos]

Are you 100% sure all U3740 voltages are good???
You already made a bad assumption about pin2.
Why don't you post values?

 

[Bouba148]

pp3v3ssd_vmon: 09V is OK , just calculate the voltage with the resistors values.

Answer to 2Informaticos and post values......

 

[PPVCC_S0_CPU]

Are you 100% sure all U3740 voltages are good???
You already made a bad assumption about pin2.
Why don't you post values?

Pin 8 of u3740 is 3.3v,
pin 3 is 3.3
pin 6 is 3.3
pin 4 is also 3.3.

i have changed u3740 yesterday when i thought .9v on pin 2 was wrong, but nothing changed

 

[2informaticos]

"Pin 8 of u3740 is 3.3v,"
Wrong assumption, as imagined...

Pins 7 & 8 should both have 0V.
I hope you checked with SSD inserted.