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    2017 A1708 820-00840 no video no back light and no chime sound

    That is what I was thinking, thanks for confirming my suspicion. Do you think it would be worth trying to heat up the CPU with some flux? What temperature and time frame would be good to try from your point of view? Thanks again for your help!
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    2017 A1708 820-00840 no video no back light and no chime sound

    Hello, I followed this post as close as possible because it sounded a lot like I have on this one https://boards.rossmanngroup.com/threads/820-00840-no-backlight-video.59001/ Below are my results so far, help!! 820-00840-a short on ppbus_g3h R5400 pin 2 short U7420 removed short gone have...
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    2019 Macbook Air 820-01521-a shorted PP3V3_G3H and flashing led on logic board

    Yes, double checked and it was .2 ohms on that line. Short went away after removing the intel chip. Thanks
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    2019 Macbook Air 820-01521-a shorted PP3V3_G3H and flashing led on logic board

    Update for reference. Installed another U7800 chip short now gone. Still only 5v at the charge port. LED light stays on solid now also. Darn, thought that was it, but no. My methods of checking voltages in order they are on the diagrams is bad for me. I should have checked core voltages and...
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    2019 Macbook Air 820-01521-a shorted PP3V3_G3H and flashing led on logic board

    Hello, By removing the U7800 chip, short goes away. Installed another chip from a donor board same thing. Anyone run across this before? This is the only chip that immediately gets hot under infrared camera, rest of the board does not heat up when I force voltage on the PP3V3_G3H. The only...
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    820-01521-02 Macbook Air 2018 No PPBUS_G3H and other Rails

    Great! What settings do you use on the hot air station for reballing? Thanks
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    820-01521-02 Macbook Air 2018 No PPBUS_G3H and other Rails

    Great! Where do I get a stencil for U7800? What reballing paste do you recommend?
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    820-01521-02 Macbook Air 2018 No PPBUS_G3H and other Rails

    When you say secondary power rails, what rails are those? I checked all the rails on page 121. Is there another page that has the rails you are referring to? As far as the U7800, do you know if there is firmware on that chip? Does your store sell those chips? Thanks
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    820-01521-02 Macbook Air 2018 No PPBUS_G3H and other Rails

    Thanks. I went ahead and replaced both CD3215 because there was a little corrosion around both. I now have 20v at usb meter but 0amps. F7000 shows 12.63v but it cycles down to 0v and then back to 12.63v. it does this continually. I rechecked F7000 in diode mode and now I get OL reading and not...
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    820-01521-02 Macbook Air 2018 No PPBUS_G3H and other Rails

    R7020 .563 diode mode I now have 5v at R7020 Looks like input MOSFETs are not controlled by CD3215 chips (what did you mean by that?) Thanks
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    820-01521-02 Macbook Air 2018 No PPBUS_G3H and other Rails

    R7020 0v F7000 1.300 L6960 .465 So I take it from the direction this is going PPDCIN_G3H would be the first voltage to make sure is there before the others? Like the PPBUS_G3H was on older boards? Thanks
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    820-01521-02 Macbook Air 2018 No PPBUS_G3H and other Rails

    Hello all, Does anybody know in what order should I check power rails as far as importance. Example, I do not have PPBUS_G3H. Should I just stop there and chase that one down first on this board, or is there another rail I must chase down first then chase down PPBUS_G3H. On older boards, if I...
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    820-01521-A - not coming on

    Hello nelo1012 I'm curious what did you do to fix the low voltage on PPBUS_G3H? Thanks
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    A1534 2017 Macbook 12" Retina famous flashing folder cannot see ssd

    All I have is a 5amp max. Tried it not much getting hot yet. The U8600 (SSD chip) not even warm??? I take it that's why I need more amps to blow the chip off the board :)
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    A1534 2017 Macbook 12" Retina famous flashing folder cannot see ssd

    Thanks. I do have a short on only 1 of the rails: PP0V9_S0SW_SSD_CORE .001 diode mode .2 ohms Verified with a working board same measurement on that line was .224 diode 365 ohms Any suggestions? There are alot of caps on that line? Also of course the ssd chip itself.
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    A1534 2017 Macbook 12" Retina famous flashing folder cannot see ssd

    Good morning all. Yes this is a common issue, most of the time bad CPU right? However, on this one all of my ssd power rails are dead. Does the cpu still cause this to happen. I though the last few that did this I had all of my ssd rail powers, but not this one. Is there a possible common...
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    820-01521-a water damage around U7650 2018 Macbook Air

    While checking the traces, I went ahead and removed U3100 CD3215 chip and saw that the 2 pads under the chip were missing, all the others were intact. The schematic says they are the following: TP_UPC_XA_SWD_DATA Pin 46 TP_UPC_XA_SWD_CLK Pin 55 According to my schematic those lines do not go...
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    820-01521-a water damage around U7650 2018 Macbook Air

    Before I started to check the coils, I went ahead and put some good flux around both CD3215 chips and heated enough to get get rid of any possible liquid under the chips because I did not know how bad this was damaged before I got it. Now after doing that I lost the 20v at the USB meter and now...
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    820-01521-a water damage around U7650 2018 Macbook Air

    Yes, checked as best as I could, visually looks good. I seen some other posts about no cap light and no usb function, I have neither. When I first plug in thumb drive the light will come on for 2 seconds solid and then never blinks or stays lit after that. Tried both ports still no usb...
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