Dm800 SE Clone 3.3V Issue

Discussion in 'Hardware troubles and Repair support.' started by gyozo75, Jun 30, 2016.

  1. gyozo75

    gyozo75 New Member

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    Hello.
    I have a clone 800SE,i have issue with the 3.3V on board supply is too high measuring 4.9V on the P1100 pin4,the resistance measured 990 ohm,after removed R1136 i have 3.4 and 4.95 on removed resistor pins.The pcb use regulators LT3830.
    Why i have 4.9V on 3.3V supply line?
    L.E:When i removed the R1136 the receiver booted,on the OLED display i have the message"Dreambox 2nd failed!"
    Help please.
    Thank you.
     
    Last edited: Jun 30, 2016
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    When I am at my work location I can give you on this a better answer.
    Because there I have all the notes, which is on Friday night or Saturday.

    But my first thought is faulty Q1105, 5v leak to the source.
    Also, since you're close to the value 914Ohm.
    But still, it could also be caused due another circuit.
     
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  3. gyozo75

    gyozo75 New Member

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    Hello.
    I don't have Q1105,this is another topology...what else i look?
     
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    In that case it's better if you give a picture from the type of motherboard you have.
    Or tell me at least which type of motherboard it is, as for example Higo24 RevD6 2011-07-29
    Because there are allot of modifications made while they where in production.
     
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  5. gyozo75

    gyozo75 New Member

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  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Okay, you have the type motherboard with the 8pins Dc to Dc regulators which you already have mentioned the LTC3830.
    And these regulators are very unstable if the coil has some issues (overheated), or with a overload.
    But also the regulator itself could be the cause, at least assuming that the input is feed with 5v, and adjusted to the output 3.3v.

    Now, maybe it's better to wait till tomorrow so that I could give you some better information about this circuit, because it's now for me hard to tell which ic delivers the 3.3v.
    But if I need to guess, than I think it could be the U7B that delivers the 3.3v.
    And maybe it's some lighting flaws, but if I take a look at you're image, it looks as if some pins has become to hot.
    If this is so, than it's not unlikely that this Ic can't carry the amp consumption, and need to be replaced for a new one.
     
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  7. gyozo75

    gyozo75 New Member

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    Yes the U7B is the 3.3v regulator,the input is feed with 12v not 5v.But i think the regulator ok,as i mentioned when i remove the 0-ohm resistor R1136 which is coming from the 3.3v regulator,i measure from the regulator part 3.4v and the other side of the resistor 4.9v and this is the big problem where is coming this 4.9V?
     
  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Question, where is coming this 4.9V?

    This I can check tomorrow, that is.. if I have this type motherboard in my workplace.
     
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  9. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Did some measurements on the same type motherboard but it's not so easy to say were the voltage come from.
    The removal of the R1136 0 ohm resistor disable the 3.3v to the cpu and other parts.

    Better it to place this resistor back, and remove the L1108 to see if the problem solves.
    If so, then it's probably the L1109 circuit, and this is mainly for the cpu feed.
    If not, then it could be due the parts as the U1108 (ddr regulator), U8, Nand chip, U1204, U700, and some places to the cpu, and also it feeds the tuner 3.3v.
    The only thing I could think of is that the dc to dc regulator has some issues when it's ballast.
    But since you say that you measure nearly 5v on the L1108/L1109 side then it looks as if the Dc regulator is fine.
    Nevertheless, see if you can figure out from which side the voltage comes by the removal of the L inductors.

    Or measure some spots as these, maybe it say's something.
    dm800se-revd13-Snap1.jpg
    The L1109 ?ohm measurement I could not do due a defect of the cpu

    dm800se-revd13-Snap2.jpg
    These are mainly some ohm measurements from the Dc regulator, but I assume that they are fine.
     
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  10. kapadok55

    kapadok55 New Member

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    Hi ,
    I have got a 2nd hand DM800se , because mine stopped working (3.3v problem) .
    This DM800 works fine BUT does not let me access it ... refuses to let me connect to put "my Data" ... It gets an ip but can't connect dcc - telnet-putty etc
    Apparently it is locked , I did a factory reset but still no joy.
    I was wondering whether
    I can upload a new image NOT by dreamup or webbrowser BUT by (say) a bootable USB

    Thanks
     
  11. toysoft

    toysoft Well-Known Member Staff Member

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    Reflash image, the box will be then clean and have no password or will have dreambox as password. You will naturally have to setup all from zero, as the image is same as if the box was coming from factory.

    TS

     
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  12. kapadok55

    kapadok55 New Member

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    Thanks for your answer ,you are right but I just found out that if I use the "mini flashup" button I could
    flash a new image & BYPASS the browser ip refusal !!!
     
  13. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    When you get a ip from dhcp network but you can not connect to it by a browser then I would try it with DreamUp with the box connected to the network, as also connected with the mini usb service port.

    Or, try it with another computer, other browser, other operation system.
    In any case, I always flash these and older boxes with DreamUp, or Japhar flasher and with a wxp system.
     
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  14. kapadok55

    kapadok55 New Member

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    Thanks again , in my case it was a LOCKED DM to a .... server , so the way I understood it was , once the full sw loaded was stopping me from connecting & getting access , so i was an acting User & not an Admin.
    Thus trying different pcs or browsers was no point . I used to flash with Dreamup when there was a com around , after that browser was so much easier - faster. I suppose any method that stopped the DM from fully booting would have been fine for me e.g keep pressing the front button as you power on ....
    I am not aware of the Japhar or wxp method ....
     
  15. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    The usb chip U901 which is only used for the mini usb service port should at least give a com port number in the device manager from the computer, even when the box not is switched on.
    Because, the mini usb chip gets his 5v power from the computer.

    When it's not working, thus you do not get a comport number in the system device manager, then the U901 chip may be faulty, or the mini usb service port has some issue, or you use not a four wired Usb to Mini usb cable .
     
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