DM800HD sim 2.01 No tuner detected

Discussion in 'DM800HD Hardware troubles and Repair support.' started by Thijs_Rallye, Nov 28, 2017.

  1. Thijs_Rallye

    Thijs_Rallye New Member

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    I recently purchased a second hand DM800HD and it appeared to be a clone. (after a no CA found :( )

    I managed to upgrade the bootloader 84D and have ran an OpenPLi image for about a month until suddenly the box gave the error no tuner detected, check tuner settings.

    So after a lot of googling around I came around this board, which has been super helpful so far. I've managed to check the motherboard voltages which all appear to be ok. SOURCE

    If the box has cooled down for some time (couple of hours) the tuner is recognized again, but after the first error I am only receiving the EPG for about a minute before the failure occurs again. After disassembly it appeared that a cap had blown, which I've replaced with a suitable one, but that didn't help either. If I keep poking around in the tuner configuration menu it will GSOD rather quickly.

    What I think is strange that I am also not able to playback the recordings, it plays for 2 seconds and then the picture freezes. The box is normally responsive and I can scroll through menu's and such.

    I've tried another (OEM Dream Multimedia) tuner and while the box boots and recognizes the tuner fine it still doesn't work. Since I don't want to kill my spare (DM8000) tuner I didn't leave it in for too long.

    If I do not assemble a tuner the box plays all the recordings just fine.

    Anyways, I have a multimeter at my disposal but it wasn't really suitable for checking out the tuner itself. I've used another guide from this website. SOURCE And I've found that I do not have a 13V at the stated pin. The tuner is a "genuine" Sim 2.01 type, Rev. M

    Is this tuner repairable, since I don't feel much for spending a huge amount of money on a heavily dated clone blox which undoubtedly has many more surprises in store for me :).
     
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hmm, okay since you have it about a rev M tuner, it may improve when you add a 510 ohm resistor as this image shows.
    This modification may help for motherboard which does to have these resistor.

    12v missing question, if the tuner is not active, then the lnb connector voltages may drop.
    If you talk about the 12v related to the LNBP21PD chip, if it's not due the L502 inductor or other parts on this circuit, then it could be due the LNBP chip self, or the inductor on the motherboard print side L32 has been burned.
    Or else may the 12v print track to it have some issues, but this is easy to fix by adding a wire between a 12v source L36 to the tuner L32.
     
  3. Thijs_Rallye

    Thijs_Rallye New Member

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    Hi John,

    Thanks for your swift reply, I highly appreciate it!

    I think you've misunderstood my post. I do not measure 13 V at the corresponding pin (which goes to the steel tuner "box"). I also don't have any voltage across the LNB output. (neither 12V or 0,58 V as the picture indicates)

    I've checked the 12V islands (?, you'll understand as a Dutch what I mean) which hold the tuner section, and I have 12V present at the connections where it should have 12V.

    Please bear in mind I am not an electrical engineer, I only have some basic knowledge :).

    Thanks once again!
     
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    If the tuner is not active, and so you have the no tuner present issue or have not configured the tuner settings then you have no lnb voltages.
    The main 12v from the motherboard to the tuner and LNBP21PD chip pin 18/19 etc should be present.

    But check this L502 inductor, if this is interrupted, if so then you have no lnb voltages.
     

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  5. Thijs_Rallye

    Thijs_Rallye New Member

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    Ok, I will try check to check the inductor tonight.

    I've just done some measurements and it appears that I do have 12,8 V present at the corresponding pin and the LNB out at a cold start. I've kept the power on for 25 minutes and the voltage is still ok, so I deceided to hook up the HDD once again and after a restart the 12,8 V was gone again.

    Pulled the power once again, disconnected the HDD but still no joy. I'll post back with results of the inductor.
     
  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hdd, when it's taken the 5v from the motherboard, then you may have a overload issue, better is to use a usb hdd with it's own power supply.
     
  7. Thijs_Rallye

    Thijs_Rallye New Member

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    I've just done a measurement on L502, which was 0,02 Ohm. (my cables were 0,04 and my measurement was 0,06)

    Regarding the HDD, it is a brand new WD 2,5" Sata drive built in the box. Do you mean I'll have to source a seperate adapter to feed the drive? Or can I feed it with the internal USB port? (which takes 5V and 12V if I am not mistaken)

    What I also have to mention is that after a cold start (and 12,8 V @ the LNB out), usually a power cycle will also kill the power to the LNB out. So that is what I am going to try next. (cold start, let it stand for about 30 mins, power cycle and measure again.)
     
  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    If the L502 passing true, just as if it's a fuse then it's fine.
    2.5 inch hdd's works only on 5v, however the dm800hd has a weak 5v delivery system and may collapse when connect a hdd to it.
    Also this 5v circuit is also used for several section on the motherboard, so when this 5v circuit is to much ballast then the box will be reset, or freeze.
    Therefore it's better to use a usb hdd with his own power supply, or to feed the internal hdd voltage with a 12v to 5v dc to dc converter but this requires some technical skills to build.

    About your lnb voltages, cold start.
    If this happens without the hdd connected, then I'm afraid that you have ballast the motherboard to much due the use of a internal hdd.
    If the box works fine without the hdd, then you may have lucky.

    Other causes could be, some issues with the dish system and so the tuner stops working.
    Try it without a lnb connection.
     
  9. Thijs_Rallye

    Thijs_Rallye New Member

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    Ok, I never knew that 2,5" drives only takes 5V for power. You can learn something everyday right.

    I just had the box run for 41 minutes and the voltage was still fine. Rebooted it (still without HDD) and now I will not boot anymore. The SSL runs up to the point where it should switch over to the desired screen resolution and then the display shuts down, the SSL bar comes back at the same location, tries to switch resolution and so on and so on.

    Disconnected the tuner and it still will not boot. I think the box is ready for the bin, unless you have some ideas :).
     
  10. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Most likely a U6 chip issue, which delivers the 5v and 3.3v.
    Not so easy to replace for a new one, and these 1940efe ic cost around the 14 euro.
    However you need to have special tools as a hot air station to replace it.

    My best advice is, if you not have the tools, and a spare parts board, then it's not worth to do a attempt to repair it.
     
  11. Thijs_Rallye

    Thijs_Rallye New Member

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    Replacing chips is indeed way beyond my skill set. Thanks for your help and this awesome board!
     
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  12. Thijs_Rallye

    Thijs_Rallye New Member

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    Because I am curious I just reflashed the box and at least it is booting again. I guess constantly pulling the power corrupted the flash or something.

    I think I'll keep messing about with this one as a form of practice.
     
  13. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yeah well, of course it could also be caused due the software and or chosen boot loader, or a bad nand flash chip as to many bad blocks.
    In any case No tuner issues does not always have to be a bad tuner, it may also be related to the (use of wrong) software.