Repair Glitches on Tuner DM800HD

Discussion in 'DM800HD Schematic drawings, Pcb images etc..' started by Johnny B., Sep 18, 2017.

  1. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Found this on the inet a long time ago somewhere and were posted on 23 February 2011 by mydalle.
    It's old but could be useful to read when you have this issue with your tuner and it's also educational.
    Anyways, here it is, good luck..

    How to Find Out and Repair the Glitches on Tuner Component Palette of DM800HD
    Posted 23 February 2011 by mydalle

    DM800HD is a popular satellite signal receiver among satellite TV fans.
    But when you are watching the programs, have you ever thought of repairing the DM800HD when it breaks down?

    The glitches are mostly happened on the scripts on tuner component palette.
    So we should learn the troubleshooting of tuner package board if we want to mend the machine by ourselves.

    DM800HD’s tuner component palette uses the plug-in mode like the PCI-E graphics card on PC.
    Its DVB-S2 integrated tuner uses the BSBE2 series product of ALPS Company and the tuner’s type is 401A.
    DVB-S2 is horizontal installed onto the package board.
    Actually, DM600 and DM7020 also use the ALPS’ tuner; however, their model series is BSBE1.

    BSBE1 tuner can only receive the DVB-S modulated signal.
    All the tuners are produced under one standard and such standard units can fit any Dreambox since they have the same pin pattern.

    If the problem is about the package board, it mainly happens on tuner and LNB feed circuit.

    1. Tuner.
    If the tuner breaks down, the tuner settings interface of the operating system will not show the model of the tuner.
    When the tuner breaks down, its I2C SCL and SDA will also breaks down, thus the chips in tuner cannot communicate with the BCM7041 controller chip.
    Then the software will think that you don’t attach tuner to DM800HD and of course there is no information about tuner.

    When the tuner breaks down, we can examine..
    The 3-pin RF amplifier.
    12-pin moderate frequency output device
    And 4-pin direct translator to see if the voltage is 3.3 volt.

    Then exam the 17-pin chip to see if it has the voltage of 1.3 volt.
    If all of these devices lost the voltage, you should exam the A6 signal control output of main chip to see if it works well.
    If it puts out 3.3 volt current that means the Q3 triode breaks down or the main chip is broken.


    2. LNB feed circuit.
    If the LNB has some problem in power supply, the LNB IN slot will have no voltage output.
    If we meet such a condition, we should exam the LNBP21 (LJ501)’s 19th pin to see if it has a 16/21 volt higher voltage.
    If the pin doesn’t have such voltage and the machine doesn’t go on standby, the error is that DM800HD is under the over current protection status.

    You can test the B4 pin of adapt plug to make sure.
    If the pin has a voltage of 0.1 volt, it means that the LNB feed circuit is under the over current protection status.
    In such status, the 2nd pin of LNBP21 won’t have a voltage since the switch inside cut down the power output.

    If the B4 pin has a voltage of 0.4 volt, it means that the L500 inductor or T500 field effect transistor or LNBP21 (U501) breaks down.
    Now, you must have solved the glitches on tuner component palette. Just start watching satellite TV programs with the repaired machine!
     
  2. Jane

    Jane Member

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    Johnny,
    Thanks for that info .But do you know how to exam that A6 line from CPU?By scope ?
     
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  3. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yeah, good question because as far as I see it, it goes to a cap from the sata connector.
    Cpu A6 -> C193

    dm800hd-Cpu-A6.jpg