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Recent content by acowan

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    mac pro 2013 - A1481 - D300 graphics card and schematic

    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
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    Any idea what CPU_ZVM_L means? Just to confirm PPVCCEDRAM_S0_REG_F is 1v
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    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...
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    Toxicity of 0201 resistors and amtech flux

    .. Or coronavirus
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    Toxicity of 0201 resistors and amtech flux

    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.
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    U4404 1.8v voltage regulator removed .. PP1V8_S0SW_DFR is now at 0.5v. Wonder where this 0.5 is coming from ... hmmmm
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    PP1V8_S0SW_DFR <-- 3.8v now that's not right Thankfully PP1V8_S0 and PP1V8_S0_PCH_VCCHDA are 1.8
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    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
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    Oh yes - I can see. I like the challenge though
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    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.
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    USB activity confirmed on a USB - USB-C converter to an external SSD.
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    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
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    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...
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    A1706 / 820-00239 - Burn at touch bar connector. All power rails good not turning on

    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...
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    USBC Power (again) 820-00840

    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...
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