820-3662 Fan spin, no vcore

[rlowe215]

Working on a 820-3662 with no signs of water damage. Costumer says he turned it of and the next day it wont start again.

Wont start at all without battery
With battery I get fan spin but no vcore present.

14.7 ohm to ground on ppvcc_s0_cpu but 0V
L7310 get 0V
PP5V_S0 5v
ALL_SYS_PWRGD 0.04v

PP3V3_S0 3.3v
PP5V_S0 5v
PP1V05_S0 1.05v
PP1V35_S3RS0_CPUDDR 0v
PP1V35_s3 0v

 

[rlowe215]

replaced U7400 and starting up but with 3 beeps
PP1V35_s3 now 1.35v and vcore are there

 

[2informaticos]

Looks like RAM issue.
Be aware, you should change all FDMF6808 chips; with new FDMF6708.

 

[rlowe215]

why change them?

 

[JohnB8812]

To avoid warranty returns. They cause random crashing/the issues you are seeing. Also going to have to reflow RAM to see if beeps go away.

 

[rlowe215]

Ok, thank you did not know that. But first of all I have to fix ram issue.