My 1st target: Trying to repair a DM800se with no LNB voltage

Discussion in 'Hardware troubles and Repair support.' started by iridium, Apr 17, 2020.

  1. iridium

    iridium New Member

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    Hi:
    This is my first message and I would like to say hello and BIG thanks for this forum that I've just found.

    I have one goal that is to restore a DM800se (clone) that can't work on it's own and requires that someone puts voltage to the LNB :) This job is currently done by another receiver that requires to be switched on when I want to use the damaged one.

    So, I will try to deassemble it and put some photos. In the meantime any guidance for the mentioned error is more than welcome.

    Best regards,
    Francesc.
     
    Last edited: Apr 17, 2020
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hi,
    Maybe the tuner may not be seated properly in the tuner slot, or some tuner voltage delivery failure from the motherboard to the tuner, or a issue with the tuner self.
    For example the L1300 inductor near the tuner slot, print side, which should give the 12vDc. in and out and could be interrupted, and check also the others Lxxxx (inductors) which should deliver the 5v (L1303) and 5v (L1301) 3.3v (1302) to the tuner slot.
     
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  3. iridium

    iridium New Member

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    Thanks Johnny:

    So basically I need to disassemble the DM800se and swap it back without tunner. Plug it in and start measuring these points (I found and marked what I understood so far that I need to measure).

    L1300 --> ¿12V DC?
    L1301 & L1303 -> ¿5V DC?
    L1302 -> ¿3.3V DC?

    Waiting for your confirmation if I got your instructions right.

    Regards,
    Francesc.

    P.S: The tunner I think it's correcly placed............when turned on the green led in it is lighting.
     

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  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Okay, thus you have the main voltages to the tuner.
    In that case it's of course easier to replace the tuner to see if it's a tuner issue, or caused due something on the motherboard.

    But based on your story, and the main voltages are present, it seems to me a tuner issue.
    If you have the regular tuner than you can check this measurements showing on this picture.
    The print side will be difficult to measure, but the parts side not.
     
  5. iridium

    iridium New Member

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    Hi:
    You got me wrong in my previous message ;). No issues......

    1. I've opened the box and just took the main board and the switch (see photo).

    (I've turned the switch on) -------> see red light between the hole. :p
    All meassures gives me 0V!!!

    L1300, L1301, L1302, L1303.......> 0V (I hope I've done it right.......kindly see first picture I've attached where I've coloured the points).

    What goes next? :)

    Thank you so much in advance,
    Francesc.
     

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  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    If you have some, or more voltage issues when measured it by the tuner slot, then you will probably also have some voltage issues by the main voltages.
    See this picture for the overview, the pins on the parts side.
     
  7. iridium

    iridium New Member

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    All voltages in "P1100" correct. :)

    So, I was measuring wrongly.........

    Now one terminal was put in GND and the other one measuring the inductors....

    L1300 ---> 12V
    L1301 ----> 5V
    L1302 ----> 3.31V
    L1303 ----> 5V

    So.........let's go to the tuner, right?
     
    Last edited: Apr 18, 2020
  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yes, since you have the main voltages, and I assuming that the box still starting up etc, as also the tuner is recognized/present in the tuner configuration, but not receive any signals when it's connected to the dish cable without any other receivers connected to the cable, but works when there is another receiver is connected to the same dish cable (which I find a bit illogical).
    And...
    When connected, without any other receiver connected to the dish cable not gives any lnb output voltages while the receiver, the tuner is well configured.
    Then it is a tuner issue.
    You could replace it for another, which is the easiest way, or do some measurements to see if it's related to a missing voltage.
    However, it does not have to be due a voltage issue, it may also be a lnb ic, or the bcm chip.
     
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  9. iridium

    iridium New Member

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    Oki........I let you know.

    I mean........the tuner is not able to GIVE 13V for the "V" or 17V for the "H" channels.....that's the issue.

    At home I have 2 receivers in different rooms that use the same dish......and share a single LNB. So in this case, there is one that is switched on to ASTRA and providing these 13V to the LNB.........so the broken one works perfectly in this situation.

    As I said......going to check voltages. :p
     
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  10. iridium

    iridium New Member

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    Magic happened...........I decided to replace the 470uF capacitor and now the LNB delivers voltage by it's own.
    Honestly speaking.......not sure if there is a rationale behind or it was just luck.

    What do you think? a) or b) :rolleyes:

    Thank you for all your answers and patience,
    BR,

    Francesc.
     

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  11. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Ah, yeah the caps, in this case the C74 470uF 16v.
    Never knew that it could give issues to the lnb voltages circuit, but good to know for future repairs.
    Anyway, nice to read that you have sorted it out and thanks for the information.
    Congrats with the result.
     
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