Tuner: NOTHING

Discussion in 'DM800HD Hardware troubles and Repair support.' started by Jane, Mar 5, 2019.

  1. Jane

    Jane Member

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    Hi Johnny,
    can be NO Tuner issue caused by faulty LNBP21 chip too?
    I have eStar DM800HD and software can not see any tuner( it says Nothing).
    Which voltage must be missing so that I receive NO Tuner issue?
    Thanks.
     
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Sorry yesterday I had no opportunity to access the interet but yes the lnbp21 may cause the no tuner issue, but of course there are also many other things which may cause this.
    As for the question about the voltages, one I know and that is the 3.3v, more about the tuner issues you may find on the tuner issues topic, but I assume you already seen that.

    The Estar tuner slot pins are the same as the other dm800hd's.
     
  3. Jane

    Jane Member

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    Johnny, thanks for your reply.
    I replaced tuner ( metal part only of the tuner module) and yet the tuner module does not work.
    I also checked voltages B1,B2, B3 and B4 and they are OK( 3.3V, 3.3V, 3.3V, and 1.2V). Also there is 12V comming to LNBP21. From my understanding NO TUNER issue is caused by a fact that CPU can not see tuner. So it can be a communication lines problem too. U600 should go to CPU. so do you think it can be U600 problem?
    Or how would you work to repair that fault?Thanks
     
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    What I do when I have a isue with a estar dm800hd box is to test it with another tuner from a regulair dm800hd box by using the tuner adapter from it.
    [​IMG]
    But of course, for this you need to have a spare parts board.
    Anyways more about this etc. see the dm800hd Tuner or tunerslot issues topic.

    U600 LM358 SMD TSSOP-8 question.
    Not sure if it may cause this, it's basically an audio amplifier.

    Anyways another thing I mostly do is to see with the serial port and a terminal program why the tuner is not recognized because it could be a driver issue.
    Nevertheless, the estar tuners are basicly the same as the other dreambox tuners, only the connector method is different.

    Be also sure that the sim card is working, in some cases the box may start normally, but the tuner will not be present.
     
  5. Jane

    Jane Member

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    Johnny,
    Thank you for the reply. I used the same trick - using the tuner adapter like you. I used the working tuner module and it was found. That means Dreambox receiver is OK, tuner ( metal box only - was tested separately ) is OK. So, the only faulty part is tuner module PCB ( an item on that PCB). Do you have any idea how to find that faulty item? Thanks
     
  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Okay so it's definitely a issue with the tuner motherboard and it's not caused due the lnbp21 chip.
    Maybe a issue between the Q1, Q2 or Q3, but I'm not sure if it could cause the no tuner issue.

    In any case, tomorrow I'm be able to give some measurements from it.
     
  7. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I'm not sure if you can do something with this information, also only to measure when you have a extension tuner slot cable because it's in the other side of the tuner pcb, but I have here two situations regards the Q1/Q2/Q3 vdc measurements.
    Black vdc measurement is when the tuner is not present due one wire interruption, other is when the tuner is fully operating with Astra 19E and set on a HD channel.
    Tuner where Rev-M.


    See pict...
    dm800hd-tuner-Rev-m-vdc-q1-q2-q3.JPG
     
  8. Jane

    Jane Member

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    Thank you for help.
    However the eStar tuner does not have T1-T3 transistors.
    But it there are voltages B1,B2, B3 and B4 and they are OK( 3.3V, 3.3V, 3.3V, and 1.2V), I think paths( normally) going through T1,T2 and T3 should be working properly.
    Or am I wrong?

    ( Not sure if you knew it but Estar Co. used this trick to replace T1-T3 . Maybe more user did not know that)
    Q1Q2Q3.jpg
     
  9. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Funny, I've never noticed it while I have a Estar box with this same modification.
    In any case, mine still works so I assume that when the two zero resistors are healthy, then it could not give the no tuner issue.

    But maybe has this modification to do with the differences of the Alps or Aerdatek tuner module ?.
     
    Last edited: Mar 13, 2019
  10. Jane

    Jane Member

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    If I understand well, you mean that NO TUNER error is because of those faulty (T1-T3) transistors alias 0Ohm resistors?
    I do not understand that because ALL 4 voltages on tuner are present and seem to be correct. It puzzles me .
     
  11. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    The main voltages on the tuner may fine, but a switching part as a transistor or bad print track, or interrupted zero ohm resistoror inductor (coil) may cause it.
    That's why I gave the advice to check at least there the zero ohm resistors.
    Of course you also need to be sure that the inductors and coils also pass well.
     
  12. oksol

    oksol New Member

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    check the I2C bus on LNBP, EPROM and metal block during the boot. If one of this devices not responding to initialization, you have NO Tuner.
     
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  13. Jane

    Jane Member

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    Thank you Johnny and oksol for your replies. Yesterday I checked various parts on tuner module but did not find any problem. Now it is a good( new ) idea for me to check I2C bus. I did not realize at all, that LNBP or even EPROM can cause NO TUNER error. I am going to test I2C tomorrow. Thanks again to both of you.
     
  14. Jane

    Jane Member

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    Can anyone let me know which EPROM IC is used? Is there a datasheet available?
    Regarding I2C communication, is it necessary to use oscilloscope and check in details both SDA and SCL ? Or is there any simple way( a hack that is for NO TUNER issue enough?).
    Thanks
     
  15. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    One is placed on the motherboard, the U8, but since you have test it with another tuner, and works, this should not be the case.
    The other is on the tuner, U400.
    However, I normally only check the print tracks to/from it because the chip itself is normally never defective.
    Checking the data to/from it I have never done, but I assume it can be done with a scope.
     
  16. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Needed to search for it, but I have here a picture which shows the U901/U400 print tracks of a Rev-M tuner.
    It may help you to follow the print tracks.

    Click on it for a full view...
    DM800HD-Tuner-U901-U400-PCBTracks.jpg
     
    Last edited: Mar 15, 2019
  17. malpi

    malpi Member

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    good i have trouble notting
    at point one I get no current 0.v
    and in the four points above I only get 11.1v
    that could fail thanks
     

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  18. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I'm not sure what you mean by point one etc.
    But assuming you have it about the 12v before/after the L500 coil then it could be a coil issue
     
  19. malpi

    malpi Member

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    It is not the coil
    is point 1 lnb power (rf input) of the photo
     
  20. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    This rf lnb input vdc power has only the voltages when the tuner is recognized, and set on a channel.
    With other words,, when you have the issue that there is no tuner to choose, then there is also no voltage output on the lnb connector.
    I think, to known if the tuner lnb circuit is fine, then the best is to check it by ohms.
    Of course, measure it with the tuner removed from the motherboard.