820-00165 PM_SLP_S4 and S5 missing

[KootenayMacGuy]

Hello

Liquid damaged board, A1466, 2015. There was a bit of corrosion around PP3V3_SUS chip (U8020) but I cleaned up the area and its working. I tossed it in the ultrasonic to rule out any hidden corrosion.

Charger is taking 29mA and not turning on.

PP3V42_G3H=3.42V
PPBUS_G3H= 8.56V
PP3V3_SUS=3V
PPVRTC_G3H=3V
PP5V_S5=5V
PP5V_S4RS3=0V
PM_SLP_S4=0V
PM_SLP_S5=0V

I have not found any shorts on any of the main power rails. I replaced clock chip, reflowed SMC, then replaced SMC. No change.

Bad CPU? Where do I go from here?

 

[2informaticos]

Put the board in UC after seeing TINY corroded area?
Why the people expect always miracles from UC?

Check for knocked off components, or broken traces.
Hot spots in UC can cause such problems.

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).

 

[KootenayMacGuy]

I put the board in the ultrasonic cleaner after my "cleanup" attempts were not successful. I figured there may be something hidden. There are a couple of corroded test points, one being PCH_I1C1_SDA, but it seems to be still connected through the board.

I have scoured the board for broken traces and knocked off components with no luck.

Triggered SMC_ONOFF_L and checked for drop pulse at PM_PWRBTN_L. It drops to .358V and holds steady, then goes back to 3.42 when I release trigger.

 

[2informaticos]

Check for pulse at PM_SLP_S4_L at same time.
Be sure PM_RSMRST_L is steady high.

You've said the board was working, after cleaning U8020 area.
Why did you insist to put in UC?

 

[KootenayMacGuy]

I apologize. I was trying to say that 3V3_SUS line, and U8020 was working, and stable. The board, however...was not powering up.

No pulse at PM_SLP_S4_L while triggering SMC ONOFF.
PM_RSMRST_L is 0V. I checked U8130 and PP3V3_SUS is getting 2.97V, 3V3_S5 is getting 3.3V. R8133 is good

 

[2informaticos]

3V3_SUS is lower than normal.
May be under U8130 threshold input, not sure.
Still problem with U8020?

 

[KootenayMacGuy]

Replaced U8020. Board fired right up. Looks like U8130 needs more than 2.97V.

Thanks!