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A long shot here - but has anyone ever seen a schematic for the A1481 Mac Pro 2013 (garbage can) I have a water damaged one that needs some attention but this will be almost impossible a schematic

Any idea what CPU_ZVM_L means? Just to confirm PPVCCEDRAM_S0_REG_F is 1v

I'm sticking with this board - something to do while I lockdown. So it seems I don't have PPVCCEDRAM_SO_CPU (0v) or PPVCCGT_S0_CPU (0v) trying to track down why PPVCCEDRAM_SO_CPU is low U7760 has 5v at pin 1 - PP5v_s0 pin 2, its enable PM_OPC_ZVM_L is 0v - should this be high or low...

.. Or coronavirus

Survived it, touch and go for a while. I'm no longer worrying about poisoning by SMD internals. I figure the 3rd-degree burns from the 861DW is what will finish me off.

U4404 1.8v voltage regulator removed .. PP1V8_S0SW_DFR is now at 0.5v. Wonder where this 0.5 is coming from ... hmmmm

PP1V8_S0SW_DFR <-- 3.8v now that's not right Thankfully PP1V8_S0 and PP1V8_S0_PCH_VCCHDA are 1.8

Yup .. EDP_BKLT_EN is missing and given how stupidly fiddly the display connector is i'm not hopeful but lets give it a go

Oh yes - I can see. I like the challenge though

No history but I've found a previous repair ? .. ? Looks like Q4400 has previously been replaced and maybe some other components. Hmm I wonder if the original problem was on PP1V8_S0SW_DFR as that's connected to Q4400 and the pin next to the burn.

USB activity confirmed on a USB - USB-C converter to an external SSD.

Does that apply to USB-C .... no absolutely sure how to check for USB-C activity other than basic current,violate from the USB-c meter Managed to get a fan spin, taken board out and narrowed it down to no fan spin when tpad is connected

No history at all All other pins checked and verified no short to ground PPVCC_S0_CPU 1.06v at C10G1 Removed J4401 and J4402 Board responds to holding down the power button - hold it down for long enough and it will take 2mA .. press again goes back into start-up routine back to 620mA I...

First attempt at fixing a 820-00239 An immaculate board, no water damage, no hot components the only area of fault is burn at J4402 between PP5V_S0_T139 and ground All power rails look good including PP5V_S0 With battery and J4402 disconnected at start up it's pulling 640mA then up to 720mA...

Quick update on this The short to ground on PP3V3_S5 on this board has ended up being a hard short (0.2ohm) at the CPU. Louis posted back in 2018 that almost all P3V3_S5 shorts on the new platforms have been CPU shorts. I swear it wasn't there when i started on this .. ahh well one for the...

yes of course ... stupid error thinking that would be accurate. So it looks like a short to ground on PP3v3_S5 and the USB-C controller might just be saving me from a fried CPU. Pulled R7691 and L7690 to isolate the voltage regulator. Despite U7650 looking like its had a blow torch on it the...

R3203 - schematic says 15k/ NEED 0.1% - measures 12k R3103 - schematic says 15k/NEED 0.1% - measures 8k Are these actually critical?? It seems unlikely

Well, I thought I had the USB-C power negotiation sorted .. It seems not. So I have an 820-00840 with no power. PPBUS_G3H 0v UPC_XB_GATE1 = 0v UPC_XB_GATE2 = 4.9v Now, why is the voltage at gate1 0 ?? How the hell does this USBC controller work

I'm not sure if the crap on the board is from where you reballed and got flux everywhere or something else but drop that into the ultrasonic - lets clear away the obvious residues as indicated by your fingerprints ;-)

Any history to the board, I'm assuming you didn't do an SMC reball without some significant event? Water spillage?