820-00840 5v not turning on

[2informaticos]

There is no short at all.
Always allow some time for discharge, after power removed; if you want to check diode mode.

 

[SMMRepair]

Yep exactly. The "short" isn't really there. Just error from instrumentation and discharge. OP ignore it.

 

[2informaticos]

Sorry man, I didn't even see wasn't Yoel who posted before...

 

[Yoel Ren]

Guys, he's obviously checking for a short IMMEDIATELY after powering off the board. OP, let the board discharge for 2-3 minutes and then check for short on ppbus. It will show a short if you check it immediately after removing power. If it shows a short, then check again after 30 seconds. Keep checking and I guarantee the "short" will go away.

yes this is the problem, thankss for this..

I only get 5v, it doesnt switch to 20v
R7020
pin 1-4 is 5v
L6995 : 3.4v
f7000 : 48mv, thats a 0 is it

 

[2informaticos]

Post SMC_RESET_ and BUF_SMC_RESET_L.

 

[Yoel Ren]

buf_smc_Reset_L is 3.4v
smc_reset_L = 3.4v

 

[2informaticos]

If board works on battery, then you still have a problem with input stage.
Try removing redriver chip.
Be sure CD3215 chips are both correctly doldered.
Post diode mode to ground on all their power rails.
Wait 30s before measure in diode mode, after power is removed (even battery).