A1466 820-3437-B 10 second fan off on

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • test_guy2010
    New Member
    • Jul 2018
    • 3
    • Australia
    #1

    A1466 820-3437-B 10 second fan off on

    Hello, I have a MacBook board that I am stuck on.

    This is a 820-3437-B board which I know the standard turn on procedure is 3 fan spins before powering up and staying on, however this board the fan turns on for about 10 seconds, turns off, then turns on and stays on until powered off.

    This board did appear to have some liquid near U1900 (clock chip) which I have replaced as well as the crystal just to make sure.

    I get all voltage rails, vCore stable at about 1.7v, very little heat coming from the CPU/PCH (mostly PCH), with a USB with a bootable system the light flashes indicating the PCH should be working.

    However it is failing to boot through as well as the strange starting behaviour.

    Odd things I have found are U3900 (camera processor) was heating up quite a bit so was taken off the board, should be able to boot without it, just missing camera functions, signal PCH_INTVRMEN is 2.6v and PCH_INTRUDER_L is 1.6v.

    I am unsure where to go from here so asking for advice, thanks.
    Tags: None
    • reformatt
      Badcaps Legend
      • Feb 2020
      • 1418
      • Australia
      #2
      Re: A1466 820-3437-B 10 second fan off on

      Check U8005 for corrosion (can be hard to spot). Seen something similar...was corrosion under pin 1.

      If that fails, flash a known working clean ME BIOS to U6100 and check all termination resistors. Are you getting a chime/display etc?

        Comment

        • test_guy2010
          New Member
          • Jul 2018
          • 3
          • Australia
          #3
          Re: A1466 820-3437-B 10 second fan off on

          No good, nothing around U8005 took it off and checked.
          Flashed a clean BIOS to the chip, resistors are fine.

          No display or chime, just the 10 second fan spin, off then back on and stays spinning.

          For now this will have to be a fail as it's been a time sink for me.

            Comment

            • reformatt
              Badcaps Legend
              • Feb 2020
              • 1418
              • Australia
              #4
              Re: A1466 820-3437-B 10 second fan off on

              Pull off the edge bonding and reflow the SMC with plenty of flux. Usually crap underneath it with weird behaviour. Also check PCH resistance to ground for PP1V05 rail. Under 100 ohm is usually damaged PCH from messed up converter feedback.

                Comment

                • Instafixx
                  Badcaps Veteran
                  • Jul 2022
                  • 374
                  • India
                  #5
                  Re: A1466 820-3437-B 10 second fan off on

                  Originally posted by reformatt
                  Pull off the edge bonding and reflow the SMC with plenty of flux. Usually crap underneath it with weird behaviour. Also check PCH resistance to ground for PP1V05 rail. Under 100 ohm is usually damaged PCH from messed up converter feedback.
                  Hi, i have the exact same issue. Wonder if this was solved. In my case if we probe the SMC_RESET_L anyhwhere on the board, the Fan Spin stops.

                  U8005 Pin #1 shows 5V.

                    Comment

                    Previous template Next

                    Related Topics

                    Collapse
                    • Tynan Dill
                      Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?
                      by Tynan Dill
                      I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.

                      Upon bringing it home and plugging it up, it showed a standby light.

                      I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.

                      The screen seems to blackout and stay black, but with a flashlight I can see the display.

                      With my Playstation 4 connected via HDMI, and running a game I can hear sound.

                      Assuming...
                      ORIGINAL POWER SUPPLY BOARD
                      7 Photos
                      11-22-2024, 01:46 PM
                    • m1ch43lzm
                      HP Pavilion 15-eh Board DAG7HAMB8F0 - CPU throttling to 0.4GHz (PROCHOT_EXT) and black screen
                      by m1ch43lzm
                      Hi, this is my personal laptop, which the original board (lets call it Board A) blew up PU8700 (TPS51486), making a hole on the board, i had left the laptop at my desk one day with the battery fully charged and didn't touch it for a week, but when i tried to turn it on it didn't
                      Thought the battery was dead, so i plugged in the charger then tried to power on, the power LED blinked once, charged LED still orange, unplugged the charger, plugged in again and I noticed the "magic smoke" smell, so i unplugged the charger, removed the back cover and saw the blown IC (the "magic...
                      05-12-2025, 08:37 PM
                    • howardc64
                      TCL 55S425 few horizontal lines, potential failure on both side of panel/buffer board
                      by howardc64
                      All left and right refers to looking from rear of TV (or looking from front with TV upside down)
                      • TV came with vertical bars and no image. Found faulty TVS on left buffer board. Also replaced T-Con (may have damaged the original while hot air removing components, board has slight warp) and have full image but few horizontal lines on the screen. Some of the lines appears to be 2 pixel tall while others are 1 pixel tall.
                      • Disconnecting left and right buffer board potentially reveals problems on both sides with different signals (unless this T-Con require jumper like Samsung FB_TRDY1&3) Fault
                      ...
                      07-24-2025, 05:17 PM
                    • Soulzink
                      Samsug washing machine. Power supply DC41-00189a board issue
                      by Soulzink
                      Hi everyone,

                      I am trying to fix a samsung washinmachine power supply main board.
                      I already replaced it with another one to fix the machine but i want to try understand the issue with the old board.
                      Therefore i hope to be able to get some help to explain what to check in order to troubleshoot.
                      The power supply board reference is the following: DC41-00189a
                      I have followed one thread (https://www.badcaps.net/forum/troubl...ingmachine-rel...
                      04-19-2025, 06:26 AM
                    • jb_Bak
                      Sony xbr-65x900c main board issues?
                      by jb_Bak
                      Hey guys great forum glad to have found it. I bought a Sony XBR 65X900C cheaply because it didn't work. No signs of life at all not even a light/led. All I hear is a brief high voltage sound when I throw the power to it.

                      Didn't see any obvious signs of damage so right away started checking voltages. This is what I see:
                      Power Board Connector that goes to Main board
                      CN6401
                      Pin 01 NC
                      Pin 02 NC
                      Pin 03 "BL_ON": 0V
                      Pin 04 "N/C"
                      Pin 05 "STBY 3.3V": 3.5V
                      Pin 06 "GND": N/C
                      Pin 07 "AC_OFF"...
                      09-27-2021, 04:52 PM
                    • Loading...
                    • No more items.
                    Working...