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  1. J

    SOLVED - 820-00840 A1708 shorted U2800

    I’ve just compared diode mode values for tpad_spi lines with known working board and they are the same. Pull-up resistors related to tpad on page 16 are all within specs according to values shown on schematic. Should I replace again U2800 or that has nothing to do with HDMI/usb disabled on...
  2. J

    SOLVED - 820-00840 A1708 shorted U2800

    Yes i have 00840 board with the chip present and it looks good. And am using the 00875 schematic and boardview on witch the chip doesn’t appear. USB mouse is working only on the boot menu same as the detected external usb boot drives. When the MacOS is launched the usb mouse is disabled.
  3. J

    SOLVED - 820-00840 A1708 shorted U2800

    No I can't start from the external disk on boot menu. When I start an external disk OS I see the apple logo with the progress bar at let say 60% and I get the Apple prohibitory sign, tested with different volumes (Catalina, High Sierra and Mojave) they all finish with the prohibitory sign. I...
  4. J

    SOLVED - 820-00840 A1708 shorted U2800

    No water damage, this board was not powering up because it had PP0V9_TBT_X_SVR and PP3V3_TBT_X_S0 shorted to ground. Removed R5640 to isolate PP3V3_S0 and board powered on fine and charged great but obviously no usb Data or HDMI output. I replaced U2800 with a preballed one and put back R5640...
  5. J

    820-01521 usb-c J3300 connector soldering

    This board came with liquid damage on the ports side, the flex and the connector (port A portion) on the board were burned and shorting the 20V rail. I Replaced the flex and the connector on the board and the short went from the 20V rail. The laptop boots ans charges. However when charging the...
  6. J

    820-3330 manual serial replacement Bios edit

    This 2012 15'' 820-3330 was brain dead with all rails, not booting, no usb mouse activity. I read the bios with the medusa and had an "Error read blockxxxx not found..." (apologies didn't write exactly the error)... Tried a random testing 820-3330 bios and it worked and booted correctly. I...
  7. J

    820-01987 all power rails but no boot

    Hello 2informaticos, Sweep function is embedded by default in my ultrasonic cleaners. I have no way to use them without sweep function. I think I have a good idea about cavities, transducers, dead or hot spots and standing waves. This board didn't have the acid very agressive damage that we...
  8. J

    820-01987 all power rails but no boot

    After an ultrasonic I don’t have anymore 20V, I have 5V 0.16-0.20A and loops on both ports usb-c meter. I still get 12.25V on PPBUS_G3H, 3.3V on PP3V_G3H and 5V on L7030. No more PP5V_G3S... It doesn’t enter DFU mode anymore. Checked around both usbc mux chip and didn’t find any short on...
  9. J

    820-01987 all power rails but no boot

    Areas affected by liquid: ISL9240 had some greeny crap corrosion, U3710 WLAN serial EEPROM, J6410 (speaker). I have just discovered 2 test points TP5905/06 completely gone ISNS_HS_OTHER3V3_P (and /N) but it seems there is no U5440 on this board... I will look again carefully and do an...
  10. J

    820-01987 all power rails but no boot

    Yes exactly, that's what I noticed on machines where a dfu restore solved the problem. And yes this T2 machine remains in off state once dfu is completed, I don't see the apple Logo that bring you to the question mark or any process to install a fresh OS... I am not sure if it's normal on this...
  11. J

    iMac A2115 2019 27'' 820-01236 EFI and hard disk detection

    Yes for sure! here is the link for "820-01236 A2115 2019 27in iMac bios" I just replaced the FSYS block the same way I downloaded. Hopefully it will be soon fully supported with medusa. https://drive.google.com/file/d/1klAL4UZMyOmIX-WVHAe1B9W6RGSk2OK3/view?usp=sharing
  12. J

    820-01987 all power rails but no boot

    Yes it seems I completed the dfu, both revive/restore I had no error but nothing happened on device under dfu. As for recovery, I don’t see how I could start it, I have no chime, I don’t see anything on internal lcd or external monitor, No capslock or usb mouse light, same with usb keyboard.
  13. J

    iMac A2115 2019 27'' 820-01236 EFI and hard disk detection

    I tried your Bios and it didn't start. Tried another one and had the same issue described (no Sata hdd detected). Finally I decided to max out the original 32 GB ssd bye replacing it with another one. While doing that I just found 2 drives: the hdd and the new ssd! I ran the fusiondrive command...
  14. J

    820-01987 all power rails but no boot

    Got this liquid damage board. I have 20V on usb-c meter. With battery I get 20V 2A so it seems charging well, the fan spins also with and without charging cable. Without battery I get 20V 0.55A. Board reacts to power button, opening the lid, pressing the trackpad or a keyboard key. I can see...
  15. J

    iMac A2115 2019 27'' 820-01236 EFI and hard disk detection

    No sorry I should have mention that! HDD doesn't show in disk utility I see only the SSD, I even tried while I was there to plug in a nother hdd but same thing. The HDD is known good because I tested it with external usb enclosure and it works fine and shows the volume. I am suspecting a...
  16. J

    iMac A2115 2019 27'' 820-01236 EFI and hard disk detection

    This iMac comes from companies returns. It was EFI locked, I did the mistake to solder the bios to an adapter and read it with the medusa 3. Instead of getting an incompatible error message because the medusa 3 doesn't support it (at least the firmware I have), the medusa read only half the chip...
  17. J

    A2289 820-01987 liquid 20V 0A

    Yes I actually started with a good inspection on both sides of the board I don't see any corrosion. I tried DFU mode Revive and Restore and it ends up with Error 4005 (can't restore the target ...gave up waiting) Nothing change...Thanks
  18. J

    A2289 820-01987 liquid 20V 0A

    Got this board slightly water damaged, It is stuck at 20V 0A. PPBUS_G3H is 12,60V PP3V3_S5 is 0V and no short diode mode is PP3V3_G3H_PMU_VDDMAIN 3.3V PP1V1_SLPS2R 1.1V PP1V1_SLPDDR 1.1V PP3V3_G3H_RTC 3.3V PP1V8_SLPS2R 1.8V PP3V3_AWAKE 3.3V PP5V_G3S 5V PMU_ONOFF_L 3.3 V I must admit I really...
  19. J

    820-00840-A A1708 20V 0A no PPBUS_G3H

    I lifted the coils on one side and found the low values coming from PP1V_S5G and PPVCCPCH_S5G...:( Removed also the feedback resistor going back to the u7800, but the low diode mode values are still present. I started to isolate components on the PPVCCPCH_S5G path (only few caps on this rail)...
  20. J

    820-00840-A A1708 20V 0A no PPBUS_G3H

    Oh forgot to post other u7000 voltages: R7075 is 5ohms and VDDA/VDDP is 5V VR1_3P3 is 3.3V A/BMON are both 0V / 0V (char only) with working board I get 0,050V / 0V (charger only) TBA_COMP is 1.1V noticed it was 1,6 and 1,5V on working board I compared diode mode reading with a working board...
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