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iPhone Xr 0.03a No Power

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  • penhitech
    replied
    No Problem Jessa, you did more than enough, I guess I screwed it up during shield removal for sure, so far I gave up on it.
    Thank you for your help again and for your assistance.

    Leave a comment:


  • Jessa_the_Professa
    commented on 's reply
    Apologies, I missed your prior update. To look for heat with a full short on main, do exactly this.
    1.) Solder a wire to the vdd_main test point near the top of the board.
    2.) Use alligator clamp to clamp to that wire
    3.) Alligator clamp to ground somewhere on the board that is metal.
    4.) Set power supply to 1v and confirm that you have current draw
    5.) Pulse the power supply by disconnecting/reconnecting the red lead again and again.
    6.) Use the thermal camera to look for heat that is pulsing.

  • penhitech
    replied
    Hi,
    I decided to give up on this iPhone, I also told the customer that I Could not recover the data from it.
    Thank you for your assistance and for your help.
    I will post again, if I need help for a different device.
    Regards!

    Leave a comment:


  • penhitech
    replied
    Hello,
    Yes, you are right, it did not make sense to me either, my power supply cable for iPhone 8(which powers up iPhone Xrs) was torn down and was not conducting current at all, I have just ordered new cables again.
    It was not my intention to add new variables to the repair, I thought Yangtze was required for the boot sequence, sorry about that.
    So yes vdd main is 0.00 in diode mode, and I am using my multimeter probs to inject 4V on the board .
    Also, red probe on ground and black probe on L5500 reads 0.00 also on C232_W I have the same result.

    Thanks for being so patient with this, and please find attached the videos you requested, hopefully, I did what you asked this time.
    https://streamable.com/b9an9k
    https://streamable.com/ko260d

    Leave a comment:


  • Jessa_the_Professa
    replied
    One problem at a time. You either have a vdd_main short—but your wire and dc power are not attached, or you don’t have a vddmain short. If your multimeter truly reads 0.00 in diode mode with red probe on ground, then it is not possible for injected 4v into vddmain to consume 0A. Something is wrong with your process.

    step one: remove Yangtze. Leave it off until you solve this problem. we never add new variables to a problem.

    step two: measure vdd_main in diode mode with red probe on ground. You have claimed your reading is 0.00
    now prove it, show a photo of the multimeter and tell me exactly where you are putting your probes. Measure two vdd_main spots because something is wrong with your results. Report both readings.

    Leave a comment:


  • penhitech
    replied
    I soldered a wire on vdd main and injected 4V, nothing is happening on my DCPS 0A, no heat, nothing, but 4v is present all over vdd main components.
    Tried regular battery fpc connection through DCPS, same thing nothing!
    The short is still active in VDD_Main.
    I put back Yangtze again, still the same thing, PLUS short on PP_VDD_MAIN_YANGTZE also (Either with Yangtze on or out)
    I don't know what's going on anymore, I think It is getting worse.
    Last edited by penhitech; 08-22-2021, 01:37 AM.

    Leave a comment:


  • Jessa_the_Professa
    replied
    Okay, you have a short on vddmain. Solder a wire to any component or pad on main and inject up to 4v. Use a thermal camera to see if there is any heat. What do you find?

    Leave a comment:


  • penhitech
    replied
    Hello,

    Diode Mode is 0.00 in VDD_main, with PA_LB_K and Yangtze off.
    Sorry though I would help with my observations, but yeah that is my current reading.
    Thanks again.

    Leave a comment:


  • Jessa_the_Professa
    replied
    We are going to focus on only one problem at a time.

    What is diode mode on vdd_main?

    Leave a comment:


  • penhitech
    replied
    Hello, And sorry for not getting at you faster.
    This iPhone Xr is driving me crazy, I did as you've instructed, and then I was curious to check the few contact point under PA_LB_K, I have found the following Using Diode mode)
    K15: Short at 0.001
    E15: OL
    B4: Short at 0.003
    E2: short at 0.000
    The other contact points matched ZXW readings.

    Also when I tried injecting 4v 2A (with both Yangtze and PA_LB_K off) onto VDD Main, I took out L5500 to solder my wire, using diode mode to check vdd main just out of curiosity the short was gone, So I figured it was the suspect, I took the same component from a donor Xr board, put it back and the short was back again, pulled the same coil again, tested it with Diode mode, and the short was still present again, I do not even know what to think of this tho, isn't that weird?

    So I am not taking any other action until I consult with you.
    And for shield removal, you are right I do use heat and try my best to make it fast, but still, I think I am causing further damage, I will try your method, and If I could I would not even use hot air, I hate doing that, I will use my soldering iron next time.
    Thank you!

    Leave a comment:


  • Jessa_the_Professa
    replied
    1.) Yes, PA_LB_K is has shifted. You need to remove this chip before beginning troubleshooting. Leave it off until later--you do not want to introduce new variables.
    2.) Signs of too much heat are around the power management chip. You will need to find another way to remove shields on iPhone XR until you are not causing too much heat on the board. Consider using a low melt alloy to make the joints require less heat, or cutting/drilling problem shields. Practice on other boards.

    Once you have removed PA_LB_K then it is time to use thermal camera to look for heat for your vdd_main short.

    With yangtze still off the board.
    Confirm that you still have 0.00 in diode mode on vdd_main
    Solder a wire to any vdd_main component. Inject up to 4v.
    Use thermal camera to look for heat--pulsing the voltage off/on at the power supply to look for heat that also pulses in sync with the power.

    Show a video.

    Leave a comment:


  • penhitech
    replied
    Hello And thank you for your answer,
    I have looked and looked and looked after reading carefully your post, I cannot seem to find that chip unless it is the one I uploaded in my attachment below, in ZXW it is PA_LB_K Chip (By the way there is almost only ground contact pins underneath!)

    So
    1) The Chip is PA_LB_K
    2) Signs of too much heat would be the same area where I took Off Yangtze( Please see attachment 2)

    I am standing still, will not do anything until further notice.

    PS: I generally use 400C, 90 air to remove shields or to solder/unsolder chips as well.

    Thank you again!
    Attached Files

    Leave a comment:


  • Jessa_the_Professa
    replied
    Thank you for sending the pictures. Step one is always "Crisp visual exam"
    That means you must notice tiny details before doing anything else.

    These photos show us two things to notice.
    1.) There is a chip that has been accidentally moved during shield removal. You can notice it because it is not perfectly square. Stare at the board under the microscope and tell me what chip has been moved.
    2.) There are signs of too much heat applied to the board from removing shields. Look for components that have tiny uneven blobs of solder sticking out. Figure out what area of the board has "signs of too much heat"

    Do not do anything else--just find these two areas and report back when you know.

    Leave a comment:


  • penhitech
    replied
    Hi,
    Oh, I thought I needed a mounted microscopic camera for that, sorry about that.
    I have uploaded 2 pictures taken with a Galaxy Z Fold 2, hopefully, that should be good enough.
    Also I took 2 Videos front and back when I was injecting 4V 2A to vdd main via DCPS.

    https://streamable.com/doxf2f
    https://streamable.com/36tfup

    It is not clear as to where the heat is coming from actually unless I am not seeing clearly.
    Thank you again.
    Attached Files

    Leave a comment:


  • Jessa_the_Professa
    replied
    That board is not clean enough to begin troubleshooting. Use 99% alcohol and a toothbrush to vigorously scrub the board, then dry briefly with 200C

    Those pictures have too much camera shake. An cell phone camera can take a suitable picture—use a tripod to avoid shaking

    If you have 0.00 in diode mode on any vddmain spot then you have a short on main. No need to measure more than one spot—if a line is short anywhere, the line is short everywhere.

    Solder a wire to any main spot and inject up to 4 volts. Use a thermal camera to find the heat.

    show a picture

    Leave a comment:

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