DM 7020 HD mainboard info?

Discussion in 'Hardware troubles and Repair support.' started by rtznfrtz, Apr 3, 2019.

  1. rtznfrtz

    rtznfrtz New Member

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    is there any information availlable for the 7020hd mainboard?
    thx to this thread i found that the psu (same as the 8000) is ok --> i applied 3.3 V by an externel psu and it worked, all voltages ok.

    also: if i loosen the psu connector to the mainboard and "wobble" with the plug the mainboard starts booting - but switches off again after a few seconds (if the plug is fixed in the right place - nothing happens at all).

    any info appreciated
     
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    No sorry but I have not much information for this type dreambox.

    As for the connector issue, some voltages are double connected, as the 3.3v.
    Be assured that you have not made other bridges between the other voltages.
    More info about the psu you can see here,
    DM7020 Rev:NPX520E7-3 psu schematic
     
  3. rtznfrtz

    rtznfrtz New Member

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    Thx for the reply, but it's a "DM7020HD" not 7020(sd) and
    the 7020HD (as stated in my first post) has the same psu as the DM 8000 HD.

    i found in an older threa that some of the caps should be replaced (e.g. C603, C705). i changed a couple of them an it did improve the situation. i need to start several times - and at first there is only a short flicker on the led's. After repeating this for 3 or 4 times the receiver boots up.
    i still think it's the psu - either not "starting" corrrectly or some sort of overload at first start?!?

    sometimes starts but switches off all of a sudden after 5 to 10 minutes
     
    Last edited: Apr 5, 2019
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Ah okay in that case it looks as if it should be a bad cap, somewhere..
    I often first replace the four caps when a psu stays not stable, but it could also be the C109 cap.

    Maybe this topic helps you a bit, Psu problems and solutions.
    But it does not have the symptoms you have.
     
  5. rtznfrtz

    rtznfrtz New Member

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    OK thx but NOPE ... changed C109 in an earlier state and now i 've changed those 4x 35V 1000. no change - same behavior as before
    --> but switch off happens even if i apply the 3.3V starting current by an external PSU - i need to disconnect and connect again to start the psu new - does that indicate something?

    and .. if i disconnct ithe psu from the mains and get it fully discharged, it starts right away.
     
    Last edited: Apr 5, 2019
  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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  7. rtznfrtz

    rtznfrtz New Member

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    detached the psu completely - and had it sitting on my workbench. BUT - it did not start when i applied 3.35V to pin 4 (using pin 2 as ground).
    replugged it to the receiver and it boots after a small "wabble" with the connector !?! (attaching and detaching the connector rapidly) with all Volt values within range - i'm a bit confused
     
  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Disconnecting the power supply from the motherboard, and adding a positive 3.3V to pin 4, and a minus to the ground should powered On the power supply.
    It may not work when it's connected to the motherboard.

    When you need to touch the psu connector, or the flat cable, or connector for starting up the box, then I think rather on a bad wire, or wire connection, probably more than one.
    I think, check the psu wires by ohm, not by sound.
    Check if they all gives a fully ohm value.
     
  9. rtznfrtz

    rtznfrtz New Member

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    1) that 3,3V pin leads only to q200 - left pin - right? (could not find any other connection) i measured 3,4V left , 0V right and 0V on the upper pin
    2) i did not write clear enough --- i need to wobble with the connector to slightly touch the pins on the motherboard by tilting the plug in its longitudinal axis (not all pins connect at the same time) to make it start/boot. the wires are all in good shape and well connected to the crimped pins)
     
  10. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Q200 question, The ..center pin.. is zero if the psu is inactive, it's active with 12v when the psu is active.
    I do not know which psu you have, but I have here the DM8000HD 25X10 PSU Voltages measurements.
    Another type, the 5L0565, see the DM8000HD 5L0565 PSU Voltages measurements.

    Q number 2,
    With this information, it sound as if you have connect a original psu on a clone motherboard, or a clone psu on a original motherboard.
    In any case, the pin female/male thickness clone/original psu connectors are slightly different.
     
  11. rtznfrtz

    rtznfrtz New Member

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    it's a 25X10 PSU and its an original DM 7020HD - i'll compare all the voltages - thx

    i see i don't get the message across. the plug fits perfect. but if it's fully plugged in, it does not start the psu and there is no boot. so i detach the plug and just slightly press it in (so its not jet fixed but the pins start touching each other). now with a bit of wobbling i get the psu to start up and the receiver to boot.
     
  12. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hmm strange issue, maybe has some voltages a issue when it's used/connected.
    But this should normally be seen when you measure the main voltages while the box is active.
     
  13. rtznfrtz

    rtznfrtz New Member

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    just measured all the "off" voltes (can't do the active values, as it's not starting when unplugged, even if i apply the 3,4V externaly)
    all OK but the 0.425V i can't find anywhere!?!
    and those 3 points on the hot side (14V) ... i have only 8 to 8.75V (--> constantly varying)
     
    Last edited: Apr 7, 2019
  14. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Could be caused due bad or outdated solder, you need to check/refresh them most likely from the hot zone, the 13v ,14v circuit, or related to it.

    Note,
    Be careful with the hot zone big high voltage caps, best is to unload them when you have plans to solder there.
     
  15. rtznfrtz

    rtznfrtz New Member

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    after some soldering i have 311 V on the hot side and by applying 3.4V i have a change on the hot side (Q200, PC100 and PC200 are switching) but no changes on the cold side (only 14.8V).
    but still the 0,425V is missing (D301 and so on ..)
     
  16. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I assume that you have the other voltages which are noted when it's in off state.
    0,425V missing, D301 center circuit etc.
    Check the L400 and L700 if they are not interrupted or maybe a bad cap C310/C311.
    However, since the voltage is so low, and I always use sensitive (Fluke) measurements devices to make this measurements, it may also be that it's not be the issue.
     
  17. rtznfrtz

    rtznfrtz New Member

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    if in doubt, i'm using 2 different multimeters ;-)

    now i've replaced the IC101 and C109 with the pair out of an older PSU - and it's starting/booting
    thx to your DM7020 Rev:NPX520E7-3 psu schematic it got a lot easier for me
     
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  18. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Nice to hear that it helped you, and fine to hear that you succeeded, and thanks for mentioning your solution. :)