Working on an 820-3115 board that has "bouncing" voltages all around. Hard to pinpoint where it starts and, obviously, what's causing it:
1. PPBUS_G3H with charger bounces from 12.26v to 12.59v and in-between over and over. Up then down, then up.
2. VRTC_G3H bounces from 3.32v to 3.43v and in-between over and over.
3. PP5v_s5, same symptoms (bouncing).
3. SMC_PM_G2_EN bounces so fast the multimeter doesn't catch it.
4. Tiniest amount of liquid corroded R5014, so I replaced it.
5. Replaced SMC, U5010 and U7941, as well as the clock, as I've seen those all cause similar issues in the past.
6. PPBUS_G3H is steady at ~12.10v with battery, no bouncing, but the board does not power on with battery.
I was going to replace U7000, but it would just be a guess at this point; I have a feeling that the cause is earlier in the power line, as it's affecting all of these down-the-line rails. I thought for sure replacing the SMC would resolve it, but it doesn't. PP3v42 is steady (no bouncing), and it's steady at U5010.
Any ideas where I should check next? All help appreciated.
1. PPBUS_G3H with charger bounces from 12.26v to 12.59v and in-between over and over. Up then down, then up.
2. VRTC_G3H bounces from 3.32v to 3.43v and in-between over and over.
3. PP5v_s5, same symptoms (bouncing).
3. SMC_PM_G2_EN bounces so fast the multimeter doesn't catch it.
4. Tiniest amount of liquid corroded R5014, so I replaced it.
5. Replaced SMC, U5010 and U7941, as well as the clock, as I've seen those all cause similar issues in the past.
6. PPBUS_G3H is steady at ~12.10v with battery, no bouncing, but the board does not power on with battery.
I was going to replace U7000, but it would just be a guess at this point; I have a feeling that the cause is earlier in the power line, as it's affecting all of these down-the-line rails. I thought for sure replacing the SMC would resolve it, but it doesn't. PP3v42 is steady (no bouncing), and it's steady at U5010.
Any ideas where I should check next? All help appreciated.