Tuner rev M only gets Verticals channels

Discussion in 'DM800HD Hardware troubles and Repair support.' started by rufino1, May 16, 2017.

  1. rufino1

    rufino1 New Member

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    Hello JB,
    nice to contact you again.
    I do not understand why my tuner rev M is getting only verticals channels.
    Working manly wiht ASTRA.
    And do not get high transponders, i,e, Euronews, for instance all those in 12.000 and above.
    I changed tuner and the same.
    PSU is OK.
    DM800HD, works well beside that.

    Any help.
    thanks a lot as usual
    Rufino
     
    Last edited: May 16, 2017
  2. bibic

    bibic Active Member

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    Check with measuring device if you have 14V on vertical polarization and 18V for horizontal polarization.
     
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  3. rufino1

    rufino1 New Member

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    Thank you for your prompt answer as usual.
    Yes I have both voltages.And the DISECQ is the best, I have Spaun
    This is weird.
    Any idea?
     
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hi,
    How the H/V switching works on the dm800hd is at this moment unknown to me but I had a case with a duo board with this issue and was a bad resistor to both of the lnb control and supply ic's
    This was only one circuits line which were high/low switching from the cpu.

    I assume that it is with the dm800hd a similar case.
    Not claiming that it is the cpu, but rather one connection to/from it between the cpu, to the tuner slot.

    When I have the time for it I could examine it, but not soon, rather the upcoming weekend I may have the time to see if I could find the pin on the tuner slot.
    But, another thing I think of, since it is frequency related, and the dm800hd has three of them, it could also be a bad crystal, but this is more a guess.
     
  5. rufino1

    rufino1 New Member

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    Excellent !!!
    I appreciate so much all your detailed explanation.I tried many different things, even different tuners.
    Rev K, Rev L, Rev M.

    The Rev K, worked one or two days great,all the channels, and all the satellites,changing the Disecq without any problem.But the third day, it worked like the others tuners.Not high frequencies and not changing Disecq.
    I'll wait you test your system.
    I'm not in a hurry, and your kindness in giving me your help, it is more than enough.
    Kind Regards
     
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  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I have investigated how the dreambox switched the H/V and 22Khz but this happens directly from the external tuner.
    The CPU can not cause this, in case of a print line issue to the tuner, it often results in a no tuner, or no signal problem.

    There is a modification for older motherboards, such as the addition of resistance that improved tuner recognition.
    But as far as I know, it's not a solution to what you describe,
    But if this resistance is missing, it is advisable to add them.

    Because you already had confirmed that the 14/18v works, then I also assume that the 22kHz switching works.

    For what I mainly read about this issue it is mostly related to the diseqc switch which could be the brand or type diseqc you use.
    As for the Dreamboxes it mostly works the best with a emp centauri diseqc switch which I also use for testing my (repaired) boxes.

    Another reason why it could fail is a bad cable to the diseqc switch, or Lnb.
    In any case a bad voltage to the Lnb.

    Thing I would do to find this issue.
    1. Checking with another dreambox receiver.
    1a. If works, use the same software on the faulty box.

    2. Checking with a sat finder, or vdc multimeter on the lnb or cable to the diseqc switch, switch side how high the voltage is.
    2a. when lower than the source, replace cable or check it.
    2b. try it with another diseqc, preferably an ems diseqc switch.
    2c. try it with another Lnb.

    I could think of more ideas, but for now seems this advices enough to find out the issue.
    In any case I have no reason to think of a Hw failure of the dreambox receiver side, or it must be due the tuner.
     
  7. rufino1

    rufino1 New Member

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    Good morning and great comments you wrote down herein.
    I'will try this coming days with this minor modification you suggest on the motherboard.
    I read all the links possible to this problem, and I've found it is more common than expected, therefore, it could be a great help for much more people.
    One thing I like of theses devices is you can touch them up and solve the problem.This is the allure they have.
    I'll be back with the experience to tell you.
    Kind Regards
     
  8. rufino1

    rufino1 New Member

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    Hello again,
    after this time I did several tests.
    First of all, I added the resistor 510 Ohms for improving tuner recognition.No results.
    I checked with another DM800HD the Disecq,and Disecq works OK.
    I mean, the other DM800-hd moved from one to another satellites with not problems thru the disecq.So disecq is working great.
    Therefore Cable-wires and LNBs are also well.PSU OK
    I changed severals Tuners I have, REV J, REV M, and all presents the same problem.

    I can only watch low Transponders on ASTRA, Verticals ones.
    Euronews Horizontal or any other Hchannels, not possible.
    It changed to one of the satellites I have seleceted, 5W, OK but only verticals

    The rest Tuner Failed.
    This is all my friend.
    Warm Regards
     
  9. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hmm, in that case then..
    The only reason I could think of is a cpu issue, or the communication between the tuner slot and the cpu.
    Anyways maybe you are be able to measure the issue by ohm measurements, thinking at one of the four connections to the cpu.
    Measurement were done from a brand new RevJ motherboard with (of course) no tuner and all caps unloaded.
    The values may differ, as long it is in range it should be fine.

    DM800HD-Tunerconnector-measurements.jpg
    Click on the image if you want to see the full size.
     
  10. rufino1

    rufino1 New Member

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    Hello again
    thanks a lot for the new information.Let have some time to check all connections.
    I'll revert right here if there is a variation with the volts and ohms you pointed out.
    Perhaps our checking can help some others.
    Kind regards as usual.
    R.
     
  11. rufino1

    rufino1 New Member

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    Hello my friend,
    here again.
    I lent a Power Supply from a friend 14Amps, to make sure the amps are not the problem, and just to check again the voltage that comes out from the Tuner.
    Well the result is 12,87 Volts, all the times no matter wich polarisation , wether V or H.
    Whatever satellite.
    This is new, considering that at the beginning the two voltages 14/18v worked properly.Not anymore.
    Therefore, we have to attack the problem from another point of view.
    This is all.
    Warm Regards,
    R.
     
  12. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I think, check this new issue with more than one tuner, because the 13/18v switching happens as far as I known with the tuner, the Tuner-U500-LNBP21PD ic.
    If the 12v to the tuner is weak due a bad inductor, or a issue with the 12v on/to the tuner than it may also be the case.
     
  13. rufino1

    rufino1 New Member

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    Hello,
    I bring you the following information, you should tell me about it.
    There is a MP8125, that as I read in some other forums, it is responsible for getting 13v or 18v-
    If I would found it, I could check it, but I can't find it.
    Is that thrue according to you?
    K.Regards
     
  14. rufino1

    rufino1 New Member

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    I checked with three other Tuners.Same bad results
    Regards
     
  15. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    The MP8125 doesn't exits on the well known tuner series, or it must be placed on newer type tuners.
    In any case has the MP8125 the same function as the regular LNBP21 which exist on most of the dm800hd tuners.

    And yeah it stays strange that issue you have.
    I had made a adapter with jumper wires and disabled wire by wire from the motherboard to the tuner to see if I could create the issue you have.
    None of them did, or the tuner disappears, or it gave no signal issues on all channels.

    I have the feeling that it is caused due the software, maybe it was not a regulair receiver, maybe it was one which only works on blackhole and a older boot loader.
    I have one dm800hd which refuses all above the ssl #76 boot loaders which gave tuner issues, but only a image file suitable for this boot loader or lower worked.
    Never had found why, but thinking of the data into the cpu because I already had replaced the (u13) bios eeprom and other (u8) programmed serial eeprom.
     
  16. rufino1

    rufino1 New Member

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  17. rufino1

    rufino1 New Member

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    During my test with the 4 tuners.
    In case is the software, could you suggest to me a suitable boot loader and software to charge the DM800HD.
    Kind Regards and endless thank you
     
  18. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Pic link failed due login issues, better is to upload it into your post reply or sites as tinyupload.com
    As for the files, for which sim card..
    Sim 2.01
    Ferrari
    Or other..
     
  19. rufino1

    rufino1 New Member

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    Hi agian,
    Lucky afternoon, I've been traying different things, images and so on,.....and finally, I made it work.
    14/18V no problems.
    The software was the issue.
    Now, it works perfect.

    I want you thank you very much for being there.I love these units, I have three more in my workshop that give me good time when I repair them.
    Appreciated your help so much
    Rufino
     
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  20. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Ah, so it was a software issue, glad that you haven't given it up and glad that you found it.
    Another mystery solved, thanks for your message. ;)