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Liquid damage from water. Corrosion around UD560 connections under that chip are now good. DCIN voltage is 5.16V on both ports and zero amps drawing. Checking the CD3217's I'm getting the LDO's on the chip related to the powered port but the readings on the opposite chip are pulsing and erratic...

History is that this board booted occasionally and now no longer boots that I've experienced. I'm wondering being that PCH_INTVRMEN is low, can I play with resistor value of R1302 to see if it starts and boots?

Yes the resistance here is actually zero ohms

Not good... pulling that coil up, the short is CPU side and I pulled what looks like a R7640 and the leg of that that is shorted is the one that sends power to CPU. Pulled the caps from and resistors near there from that leg just on a hope and a prayer and the short is still there so it appears...

This is 2014… so soldered on

Will do. It is a dead short: 0 ohms

Not sure how I missed this before. ONe of the coils (looks like L7630 circuit from a 820-3476 board maybe??? P1V05 SO?) It appears I have a dead short on that line zero ohms resistance to ground.

No luck on those but was a good thought. Not seeing familiar PP3V42 components but I do have dropping values around the SMC. Any idea if this board should have PP3V42_G3H? Some spots I'm getting 3.38V but I think that is actually PP3V3_S5... If the dropping voltage measurements are supposed to...

No pulses at other large coils with power button, just steady 3.3V on the one. So I take it no voltage at middle pin of power supply connector is normal? I did verify that the power button closes the circuit correctly so it works at least. I tried SMC bypass just to see but guessing wont work on...

This one is dead. I get 12V from 4 pins on power supply to board. Is center pin of the powersupply connector supposed to have any power? No fan spin or chime. I have 3v3_s5 and nothing at what I believe is the PP5V_S4 coil. Diode on that coil is .402 and diode check around U7501 seem to be...

This can be marked as solved. USC didn't change anything but being LI were triggered on battery, and my Medusa was unable to program the chip on board, I checked the SPIROM traces and discovered a missing connection from R5121 to U6100. Board now boots so should be good to go.

I had tried the other all_sys resistors already but forgot about q7950. No luck with any of those or pulling the GPU coils. I'm going to give it a bath and pray.

Testing on the bench with nothing connected to the board but power. Can see a slight twitch on the fans at times. Was able to verify that all major power rails are pulsing but present at correct values and PLT_Reset)_L pulses also. Resoldered U8900 just in case. Tried new BIOS and CLeanME...

Yes. I've tried on bench by itself also. Try flux on the cpu and if same then RAM?

I have a rather strange issue. THis Mac shows the following error from report when it did allow login: mp_kdp_enter() timed-out on cpu 1, NMI-ing mp_kdp_enter() NMI pending on cpus: 0 2 3 mp_kdp_enter() timed-out during locked wait after NMI;expected 4 acks but received 2 after 29671276 loops...

None of the 4 ports are boot looping. All of them are at 5.15V and 0 amps. None of the caps around CD3215's appear to be blown. Was getting 0V at PP3v3_G3H but I've replaced: C6906, U6903, C6910 and D6902 and now I do get 3.4V at PP3v3_G3H but diode reading I think is slightly high at .487 red...

THis came in customer said suddenly died. Started, no boot. NO signs of liquid damage. COuldr read ROM but couldn't write to ROM with MEdusa so replaced U6100 and reprogrammed with new BIOS clean ME. Realized board booted with heat to PCH so reflowed with flux. Board now boots consistently but...

Voltage dropped? to 1.2V with C7095 removed but guessing that didn't cause the drop. Regardless, no pp3v42 present still. Diode at L7095 is .313. What do you mean Ra/Rb to get correct voltage?

Board isn't necessarily clean but no liquid contact or relevant visible corrosion. PP3V42 is usually either 1.5V or 2.2V with no correlation to anything I can tell. Board is on bench and checked with Main flex cable removed also and tried with different DCIN board. Things I tried: replacing...

Came in dead. POwer supply is registering AC input no DC output, tried two other power supplies and same result... is it possible the board or something else is pulling those DC outputs down or am I correctly thinking that this is just bad luck and I've got two other bad power supplies? Just...