DM900UHD Motherboard pictures

Discussion in 'Schematic drawings, Pcb images etc..' started by Johnny B., Dec 10, 2016.

  1. bibic

    bibic Active Member

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  2. toysoft

    toysoft Well-Known Member Staff Member

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    The MAC is inside the TPM/Security chip, so you cannot have two devices with the same MAC.

    Check the image, perhaps it was modified to set the MAC after Linux boot, and remove the MAC set by it... or flash another image and you will have then the original MAC of your boxes (different naturally).

    TS
     
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  3. rodina

    rodina New Member

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    Hello. Please tell me which parts of the board are powered by these chokes?
     

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  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    First of all, sorry for responding late, but these are busy days before the end of the year and the virus thing.

    I can't draw it right now so the best I can do is refer it to you in the datasheet. See the 3x VIN, Pins 32,33,34, that is together the main voltage.
    This input can be 4.5-V to 18-V, but I assume it is 12vDc input or a bit lower.

    The coils you show are most likely output voltages.
    See the Typical Application Schematic for an example how it basically is connected as also the Pin Configuration and Functions overview in the datasheet.
     
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  5. rodina

    rodina New Member

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    Perhaps the central processor is powered by the chokes?
     
    Last edited: Dec 17, 2020
  6. rodina

    rodina New Member

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    They have the following voltages 1v, 5v, 3.3v.
     
  7. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Based of I had measured a while ago are these voltage outputs fine.
    See this picture for more voltage overviews.

    And just in case you have this issue, read this topic.
    when you experience the..
    When you try to access the rescue mode by a browser, but you only get a white screen with the message Content-Type: text / html; charset = utf-8 on it.
     
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  8. rodina

    rodina New Member

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    My receiver is generally dead, there is no log through the service port. There is a suspicion that the processor is not working. The chokes that did not work correctly in the photo before were checked with an oscilloscope. But now it itself worked correctly. Here is the question, can this all be due to a possibly faulty processor?
     
  9. toysoft

    toysoft Well-Known Member Staff Member

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    I have exactly the same thing with my receiver, DM900UHD, it has the frontpanel red light, and on the back there is nothing coming out from the Service Port... if I remember well. CPU is like dead, but still hot... check if yours also get hot or not.

    TS
     
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  10. rodina

    rodina New Member

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    Yes, mine also has a hot processor.
     
  11. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    A hot cpu could indeed indicates that it has issues.
    In some cases due a missing voltage, which could be a damaged/interrupted inductor near the cpu if all the main voltages are still present.
    On the print side there are several inductors placed, the print numbers starting wit BD, for example BD1715.
    Check if one of them are missing, or interrupted by ohm measurement.
    This needs to be done while the motherboard not has been powered.
    See this picture... for a good overview.

    If this is not the case, then a damaged cpu is still possible.
     
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  12. rodina

    rodina New Member

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    I checked the inductors with a multimeter, they are in order.
     
  13. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Than the chances that it could be a damaged cpu are a big more likely.
    Whats left is to measure the main places by ohm as you already may have seen on this image, the yellow measurements.
    These were measured between a ground spot, and the measurements spots.

    They do not have to be precisely the same as long they are in the range.
    When one of them are totally out of range, then it may be a issue with these circuit, maybe a bad dc to dc chip, or the output coil.
    In most cases also noticeable when a coil become hot, then it may wise to replace it to see if it helps.

    When more places out of range, as the 1v/1.7v/3.3v ohms value, then it's more likely that it's a damaged cpu, or some issue under it.
    A bug may cause it, I have it seen more with repairs.
     
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