Vu+ red led only, jtag connected, no voltages on u204

Discussion in 'VuPlus Duo Hardware troubles and Repair support.' started by pnung, Nov 19, 2018.

  1. pnung

    pnung New Member

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    Hi.I have vu+ with red led Problem: voltages for f803, f804, f812 and f813 are fine. Jtag PIN have 3.3 voltages. CPU is heating ...
    Jtag get connected (green) but can not get flash infornatiom on Flash Explorer (refresh).
    Input Volatge u204 are fine but all other pins on u204 dont have voltages. Any idea what i can Check? Cheers pnung
     
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    When all the voltages are fine, and you have already replaced the famous c807 cap that also not helped, and you can't reach the nand flash chip with the bbs software and Jtag.

    Then I'm thinking that you need to replace the nand flash chip for a new one.
    However, in some cases it can be caused due a bad connection of one of the I/O connections from the cpu to the nand chip.
    This can mostly be measured by ohm, all the eight I/O pins should be is the same ohm range, when one is not, then it can be a bad connection to/from the cpu, or a bad nand flash chip.
     
  3. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    As for the u204 question, the U 204 is for the Usb ports and may only be active when the box starts up.

    [​IMG]
     
  4. pnung

    pnung New Member

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    Hi.
    I musst explain a bit more in Details:
    This vu+ duo had some blown ics
    U411, U412 AND U204. I replaced this three ic already from another CPU broken board .
    Please see attached picture, the scart ic is still blown, i dont think this can be the problem or ?
    I think this vu+ duo had have some electric short cut in the past.
    Back to the flash chip, are the flash chip data lines connected direct to the CPU or is there somethink line a controller in between cpu und flash Chip.
    Do you know how to messure if flash Chip get the right voltages to work?
    I can belive that some other parts are blown that not vissible by eye. What do you think about ?
     

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  5. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Based on your picture then you need to replace the U602, or at least to remove it to see if the box want to start up.
    Q nand chip, the eight I/O pins are directly connected to the cpu, vdc measurements of them should be around the 3.2v, however these are data pins and could be better measured by ohms, or with a scope.
     
  6. pnung

    pnung New Member

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    I gave up on this box. After replace U602 the vu+ still dont start up. I will use this box for spare parts.
     
  7. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yeah, in some cases it's wiser to use it for parts instead to spend to much time and money to it.
    When in doubt, it is better to leave it for a while and to take a fresh look again after a while.