820-2936 Not Recognizing HD

[brunomotter]

Hello guys. This board came to me with no life. Someone had already poked around it. I reballed SMC, replaced battery current sensing resistors and board started. It does not see HDD though. Replaced cable with known good one, still same. Mesauring around I found R4535 was bad so I replaced it. Same result. I decided then just to replace all caps (C4510, C4511, C4515, C4516, C4534, C4533, C4514, C4519, C4535 and C4536) still same. Replaced U4510, still same. Chip is getting power on VDD. EN signal is around 1,5V, which I think is low. Tried forcing it to 3.3V via jumper wire, but it still does not see the drive. What else could I verify before declaring dead PCH?

 

[2informaticos]

U4510 is powered from 1.5V, does not accept 3V on any pin.
That is the reason of series caps.
You could killed the chip forcing enable signal with 3V; change U4510, to discard this problem.

If you get 5V_S0_HDD at J4501 and U4510 is good, then the problem is on the PCH side.
Change the series caps on that side too.