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Thanks John, I'll take a crack at removing one from a donor board and see how I go.

Anyone know of a video for this? I haven't done one before and just wanted to see what was involved swapping out a USB3 port on a macBook.

PP3v3_S4 spikes to 2+v for a moment two or three times when I first connect power.

Customer said he messed the tiniest but of liquid on the keyboard and next morning it wouldn't turn on. Board is one of the cleanest I've seen. Absolutely no trace of any liquid anywhere. It isn't even dusty. PPBus = 12.59v PP3v42_G3H = 3.42v PP3v3_s5 = 3.33v PP3v3_s4 = 1.9mV PP5v_S5 = 5.02v...

Got continuity back. Replaced u7501 with a new one. PP5v_S5 @C7505 is 0.9v now. Crappy soldering maybe?

::23 has continuity to C7540 et al, but ::24 has nothing to Q7560.

Not specifically U8020, but 3v3SUS_EN. The traces around U7501 are horrible but seem to beep out ok.

P5Vp3v3_VREF2 = 1.46v

U8020 isn't getting P3V3SUS_EN

PPBus = 8.57v PP5v_s5 = 1.045v pp3v3_S5 = 0v PP3v42_G3H = 3.42v Investigating 3v3_s5 first. -- side note for later. S5_PWRGD @ R1841::1 = 3.42v R1841::2 = 0v

Had a liquid spill exactly on C7500 and C7503. Since C7500 is 8v and C7503 is 5v, is it fair to guess a dead U7501?

Actually a working board is the same. Out of ideas. :/

I ran some flux around the SMC, but no change. Have noticed that CPUIMVP_TONA & B drop down to 0.6v when the fan spins, then pop up to 12.58 when it stops @ R7402::1 & R7403::1 but the voltage on ::2 stays at 12.58v. Could this be a faulty U7400 pulling it down? After this I'm out of ideas as...

Actually, a test point near C7524 is a little corroded too.

The board is in oddly good condition aside from that single test point. I have gone over it closely and not found anything. Could that test point link to or something else?

PGoods are unstable. CPUIMVP_PGOOD sits at 3.3v, then bottoms out to 0v, back up again. CPUIMVP_AXG_PGOOD floats around 200mV.

It's like it's trying to pass POST but something is browning out and stopping the process.

So I noticed the TP for CPUIMVP_ISUM was corroded and broken. I ran a jumper from R7407 -> R7406 and to R7410. Now, with no ram I get a ram beep. If I insert ram the fan spins for a few seconds, then stops and spins for a few seconds again, then stops etc....

Customer said it was showing colours on the display from time to time then just went dead. USB mouse doesn't light up, never chimes, PRM Reset does nothing and fan spins high. CPUVCore @ C1655 is 0.678v and Diode to ground is 0.001v

You can mark this solved. I ran a very short jumper wire to what was left of the test point next to R7704 and backlight with brightness works again.