820-00165 PP1V35_CAM Shorted

[No-Clean]

Clean board in S0 state U3900 heats up as PP1V35_CAM is shorted, I replaced the U3900 chip but the short comes back after I install a new U3900 with U3900 removed the short is gone, U2800 also gets a little hot.

I am puzzled with this board.

 

[2informaticos]

What is the exact ohm value of the short?

 

[No-Clean]

0.8 Ω

 

[2informaticos]

Really strange; try changing U4000 too.

 

[No-Clean]

Removed U4000 short still there, replacing U4000 at this point will be useless.

One thing to note is that it is hard to remove U3900 without damaging it, the solder is very hard to come to melt and by the time you remove it you may have fried the chip, so to remove it from donor board I applied max hear and air from under the donor board and eventually it comes off without damaging the chip, then reball the chip with 183c paste and install it with 365c and no damage should occur to chip, but in my case I have tried 2 chips and short still there.

 

[No-Clean]

Ok some of my donor boards were also shorted on that same line and I did not bother to check and end up installing 2 bad chips, finally I checked and found a good one, short gone but now board makes it to S0 state but no boot.

PP1V05_SUS 1.5v
PP1V5_S0 1.5v
PP1V05_S0
PP1V05_S0 0.35v
ALL_SYS_PWRGD 0.06v

 

[2informaticos]

Diode mode at L7630?
Check voltage and enable signals for U7600.

 

[No-Clean]

0.166 diode mode on L7630

U7600
pin 12 5.1v
pin 8 1v
pin 16 3.3v
pin 17 0v

 

[2informaticos]

Change U7600.
Check all its traces, solders and surrounding components.

 

[No-Clean]

Diferent behaivior but not boot, Im done with this board, thanks for help!