820-4924-a wont turn on

[estelanim416]

J3700 i think! Let me check it now

 

[estelanim416]

3.3v on the J3700 PP3V3_S0SW_SSD_FLT I hope that is the one.

 

[2informaticos]

Sorry, my mistake; read U3740 instead of J3740...

 

[estelanim416]

U3740

Pin 1 3.4v , Pin 2 0.98V, Pin 6 3.22v
While on

 

[2informaticos]

What about the other pins???

 

[estelanim416]

sorry, Pin 3 - 3.28v, pin 4 - 3.43, pin 5 - 0v, pin 7 - 0.022v, pin 8 - 0.993v

 

[2informaticos]

Strange to have 1V at SSD_CLKREQ_L.
I think PCH cannot recognize the signal.
Low level should be less than 0.8V in theory...
Change U3740 and see what happens.

 

[estelanim416]

Hi

Swapped U3740, Pin 8 is now 0v, Pin 6 3.15v other pins are the same, still the same outcome :/

 

[2informaticos]

So U3740 was bad.
Check again control signals and power rails at J3700.
Pay atention at continuity between J3700.and U3710/11; maybe need to change them too.
Did you try known good SSD again?

 

[estelanim416]

apologies, there are other differences on the U3740
Pin 1 3.43v
Pin 2 0.994v
Pin 3 3.288v
Pin 4 0v
Pin 5 GN
Pin 6 3.25v
Pin 7 starts at 1v and slowly goes down
Pin 8 0v

Maybe I didn't do it right?


J3700

Pin 1 3.33v
other power pins share this power line it seems.
I am sorry to be so ignorant, how would I recognize pins for control signals? How would I test them?

I went through every pin on J3700 and there doesn't seem to be a direct connection to U3710/11 so that I could test the continuity, I am guessing I am doing it wrong

This SSD works in another MacBook so I don't think its the SSD

Thank you for your patience and the assistance

 

[2informaticos]

"Pin 4 0v"
That is bad; SSD is kept in reset...
You should get 3V at both pins 3 & 4.