Tuner (S2X-MS i.e. Si2166D) works only via LNB-Loop from another receiver.

Discussion in 'Hardware troubles and Repair support.' started by Rudo1111, Aug 23, 2023.

  1. Rudo1111

    Rudo1111 New Member

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    Hello, I want to ask if anyone has encountered the fact that the tuner in my case DM900 UHD type: (S2X-MS i.e. Si2166D) works only via LNB-Loop from another receiver?
    - if I give a functional Sat. coaxial cable directly to LNB1 or LNB2 tuner has no signal. The led for the tuners is off.
    - the tuner works fine in the second DM900 uhd.
    - Image I tried all the possible ones still the same without signal, it only goes through another receiver via Loop. (MB board is rev 0.3)
    - if the LED is ON via the tuner via the Loop from another receiver, the picture works, decoding everything goes as it should. well thank you
     
    Rudo1111, Aug 23, 2023
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  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hopefully someone else can help you with this because I have no experience with this type of tuner.
    My best advice is, and what I would do is test it on an old type of tuner.

    Another idea is to run the rescue mode, sometimes that works through a renewed boot-up.
     
    Johnny B., Aug 23, 2023
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  3. Rudo1111

    Rudo1111 New Member

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    Another tuner in this DM also does not work.
    So today I measured the board on DM and I did not measure 12V on EC107 - BD106. (someone has already made modifications there, maybe replaced the CK10035V capacitor with a 50V100uf). It will probably be a problem with the power supply to the LNB tuner as there is no 12V.
     

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    Rudo1111, Aug 24, 2023
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  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    It took me a while to answer because I had to figure out this 12v tuner circuit.
    But this is about it as far as the tuner 12v supply is concerned.
     
    Johnny B., Aug 25, 2023
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  5. Rudo1111

    Rudo1111 New Member

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    Hi, thank you for the advice, so I measured the values, see. a picture. I have 12V for part of R2011 from it only 0.41V. Thanks for help.:)
     

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    Rudo1111, Aug 30, 2023
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  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    The other side of the R2011 should be around the 4/5 vdc to turn on the Q2102 by powering pin 2
    Maybe the Q2102 has a defect.

    But it could also be a defect/shorted Schottky diode D2101/KL1 sot23-3 which seems to be the BAT54.
    It has only one diode between pin 1 and 2, you could maybe check it on diode measurement.
    See if it's shorted, replace it if it so.
    If not, than it could be the Q2102.
     
    Johnny B., Aug 30, 2023
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  7. Rudo1111

    Rudo1111 New Member

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    Hi, thank you for the advice, so I measured the values, see. a picture. I have 12V for part of R2011 from it only 0.41V. I also tested diode D2101/KL1. Thanks for help.
     

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    Rudo1111, Aug 30, 2023
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  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    From what I can see it looks like the q2102 is not working.

    But wait until the weekend, then I'll be able to check your measurements.
     
    Johnny B., Aug 31, 2023
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  9. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I found out that this was previously discussed on this page where the member mentions that the H5XG2 can be replaced by the IRLML5203, which has also been tested.
    I've also updated the drawing with more information because apparently it's more common for it to malfunction.

    In any case, you will have to replace the H5XG2 with a new one.
    The IRLML5203 is easy to get, also on aliexpress.
     
    Johnny B., Sep 1, 2023
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  10. Rudo1111

    Rudo1111 New Member

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    Hello, today I received the H5XG2 (10 pcs :) ), I changed it on the board and the DM900 worked for about 3 minutes. then I didn't have 12V for the tuners, see. picture no. 1. So I soldered a zero resistance and brought 12V above the H5XG2 chip, see. picture no. 2 and the DM900 with the tuner works like clockwork. :). Thanks for the advice and help, I hope it will work forever :)
     

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    Rudo1111, Sep 19, 2023
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