DM900UHD4K, won't start (red LED fixed)

Discussion in 'Hardware troubles and Repair support.' started by Melgas, Feb 24, 2021.

  1. Melgas

    Melgas New Member

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    Hi @Johnny B.

    My Box: DM900UHD4K, won't start.
    Keeps the red LED fixed, without action.
    I followed the instructions in the Post: "Howto connect to the mini usb service port from a dm900 / dm920 ...", at https://jb8a8f8.com/support/index.php?threads/dm900-original-fatal-error .562 / page-2 # post-5449.

    I did not succeed. Please see the images.
    I wonder if there is a solution, or if the Box is not recover.

    Thank you very much.
    Hugs.
    #
     

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  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hmm, it seems to be a second stage issue, mostly caused when loaded a incompatible or corrupt image file.

    I thing, a good start is to see if you can reach the rescue mode etc.
    Turn the box on, and a 10.000 millisecond later touch with one of your fingers the front push button.
    Keep you finger on it until you see the rescue mode on your tv screen.
    Upload a new image etc.

    I especially had say the second because it's a bit tricky to activate it.

    Other things/ideas what might help you, you may find here.
     
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  3. Melgas

    Melgas New Member

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    Hello, @Johnny B.

    You replied, stating:
    "Hmm, it seems to be a second stage issue, mostly caused when loaded a incompatible or corrupt image file."
    "Turn the box on, and a 10,000 millisecond later touch with one of your fingers the front push button.
    Keep you finger on it until you see the rescue mode on your tv screen.
    Upload a new image, etc. "

    When you says, that it may be an incompatible or corrupted image file, I remember that the Box was working well, only with a problem of viewing some channels in the Tuner C/T2.
    Entreguei a Box aos técnicos, para reparar.
    But, the technicians reported that they had found no problem and returned the Box.
    When I installed the Box, it didn't work anymore.

    Is it a file that they will have installed to do the tests (incompatible or corrupted)?

    Unfortunately, I am unable to enter boot mode.

    Hugs and thanks.
    #
     
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I do not exclude that it might be a hardware issue, but because of the limited information I had get, I needed to start with the basics, before I advice to give hardware support.

    A good start is to know, does your box has a security sim card, or a decoding chip instead.
    And when it has a sim card, which one, what is printed on it.
     
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  5. Melgas

    Melgas New Member

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    Hello, @Johnny B.

    My Box is original, has no sim card, or a decoding chip instead.

    #
     
  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Okay, then some ideas...
    1. Be sure that your 12vDc power supply is good, and has enough Amps for using it on these box, by doubts test it with another 12vDc with at least 3Amps power supply but check the polarization, center hole must be the positive side.
    When it's not than,
    2. Remove the tuner, and check (X) > with putty serial mode if it makes a difference.
    If not then also,
    3. Press the front panel push button, and go to (X) >...
    If not then also,
    4. Disconnect the front panel, and go to (X) >...
    if not then,
    5. Plug a usb stick in it, it doesn't matter if it has data/or not on it, and go to (X) >...
    if not then......
    Change the serial mode Bps to Bps 9600 and press the CTRL/C buttons on your keyboard, and switch on the box.
    When that's working than you hopefully get into BOLT mode which gives you the possibility to flash the rescue-dm900.bin file via usb with the following command.
    BOLT> show devices
    BOLT> dir usbdisk0
    BOLT> boot usbdisk0:/rescue-dm900.bin
    Notes that the rescue-dm900.bin file must be present on the usb stick.
    You can find the file on dreamboxupdate dot com.
    And take the newest one.

    However, to access this Bolt mode option is only possible if this is still present on the nand flash chip.
    Some image files removes this option.

    Other options as by telnet are only possible if you find a way to access the box through the network.

    With some luck, maybe this still works..
    By using an usb stick and and label it DREAMFLASH
    Download a image file from, dreamboxupdate dot com.
    And rename it to,
    dreambox-image-dm900.tar.xz
    Place it on your usb stick etc.

    When placed in your usb port, turn the box on, and directly touch the front touch button etc.
    With some luck it flashes the image file to the box.

    When succeeded,
    best is to after it's booting to go to telnet and to do the, update-rescue -v to have the latest rescue image.
    With some luck and thus succeeded,
    Upload the (latest) image file you like.

    Remember that this all are just some ideas which may helps to solve your issue.
    There is no guarantee that it will help in your case.

    Later, after writing this, I noticed that you already had done allot of attempts and gave the idea to given up this box and bought a new dm920 box in the linuxsat-support forum site.
    That is of course no problem, but it would have been useful/helpful in giving advice if you had mentioned that.

    HW issue.......
    In any case, when all above didn't give any indication in the terminal screen that things change, same as powering the box on with nothing connected than only the usb service port, and motherboard, and another power supply.
    Than it may be a hardware failure, than you could consider to do some measurement of the main voltages on the motherboard.
    Only do this if you have the skills to do it or you risk severely damaging the board.
     
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  7. Melgas

    Melgas New Member

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    Hi @Johnny B.

    I thank you very much, for all your effort and interest in helping me.
    I followed all your instructions.

    I was unable to disconnect the tuner + the front panel.
    Very difficult. I was afraid of breaking something and destroying the pieces.

    I used the serial cable: Mini-usb DM900 to USB PC.
    I got the COM Port.
    I ran Putty - Serial.
    I put the files "zImage-rescue-3.14-r0-dm900-20200227.bin" in PEN (FAT).
    Nothing worked.
    I just got:
    FATAL ERROR
    BOOT 2nd image failed.

    It means that the Box has a corrupted file.

    I put the files "zImage-rescue-3.14-r0-dm900-20200227.bin" in the PEN (FAT).

    Nothing worked.

    Thank you for your help and support.
    Hug.
    #
     
  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Some things you need to known is
    zImage-rescue-3.14-r0-dm900-20200227.bin
    must be renamed to..
    rescue-dm900.bin

    Also when use the dreamflash usb method to do a attempt to flash a image file,..
    Then the image file must be renamed to..
    dreambox-image-dm900.tar.xz
    The usb stick must be labeled to..
    DREAMFLASH

    I'm not say that it than works, but these seems to be the way how it should be done.

    Further it is a bit strange that you only can reach the box with the serial mode and based on the terminal output is seems to be crashed in the beginning of the boot cycle.
    Maybe it's indeed a memory block hardware issue, maybe some outdated solder balls under it and maybe with a reflow fixable, but that's more a job for someone with some skills and knowledge how to do a reflow job.
     
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  9. Melgas

    Melgas New Member

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    Hello @Johnny B.

    I renamed the files, as you said.
    But the Box is inactive.

    It seems to me, as you say, a hardware problem in the memory block. Only a specialized technician can recover this Box.

    Thank you very much for your help.
    Hugs.
    #
     
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  10. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yes but be aware that memory block errors not always has to be a real memory block issue.
    For example, suppose that there is a hardware issue with the front panel as the display.
    And when it become active, it drops some voltages as the voltages which are used for the memory, or cpu.
    Than you may also get this memory error.

    Therefore I always advice to disconnect the front panel, as also (because you had tuner issues) to remove the tuner.
    And to see in the putty serial mode if the box will start up, without these connected.

    Only then, when it still doesn't make a difference, than you may assume that it is a memory issue.

    As for an attempt to make/create a network connection by tftp, you could try the method which can be read on to japhar forum website.
     
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  11. hecha71

    hecha71 New Member

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    Hi, Johnny B such a problem, the red LED, the log can not be removed .here are the voltage measurements
     

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  12. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I think, check the security chip pins by ohm.
    See if it's near the ohm values as I had measured.
    I'm not claim that it is caused due a defect of one of this circuit, but it may indicate something.
    Measurements ohms were done between a ground spot and the measurement pin.
    And without powering the motherboard.

    In any case, my first thought is a shorted or damaged cap due a missing 5v on it, but it may missing because it is in error state.

    Further, I always advice to check the motherboard without the front panel, just to exclude the possibility that it could be caused by it.
    When disconnected, check is with a program as putty and the usb mini service port.
     
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