[SOLVED]820-2936-A Wont detect ANY hard drive

[corona2640]

Hello, I have a late 2011 820-2936-A that will not detect any internal hard drive, It can boot from a usb and then work fine except it will not see the internal hard drive. I have tried 5 different cables and hard drives with no luck. Where should i start?

 

[dukefawks]

Does it spin up?

 

[corona2640]

Yes actually it does spin up

 

[Gurmon]

ok, then lets start by checking R4533 - 36.

Does U4510 get 1.5V on pin 6 ?

Also there are lots of shitty third party HDD flex cables . You tested one of your new ones in a known good laptop ?

 

[corona2640]

R4533 and 36 check out but U4510 pin 6 is 0v

 

[Gurmon]

U4510 without any input power could be a problem. Check if any power on pin 16 of U4510?

 

[corona2640]

No power on pin 16, 0v

 

[dukefawks]

Hmm, possibly missing 1V5_s0 completely. Is 1V5 present on L7770? Short to GND on this rail? Audio will be missing too if 1V5_s0 is not there.

 

[corona2640]

No voltage is present on L7770. I checked and you are right, there is no audio also. I tried to test for a short to ground and did not detect one, To me it matched up with a known good board but i have never tested for a short to ground before so I'm not positive i did it right.

 

[aprendiz]

Check voltage on pins 1 and 3 from U7770, with board powered on....

 

[corona2640]

Pin 1 has 3.2v but pin 3 has pretty much zero v

 

[dukefawks]

Pin 3 enable comes straight from SLP_S3 through R7988. SLP_S3 must be present for the board to work so I bet U7770 is dead and pulling down the enable signal after R7988. Replace U7770

 

[corona2640]

Fixed, it was U7770. Thanks again guys