1. Jules

    Jules Active Member

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    I have just been given a Duo to work on.
    It has a U702 chip board inside.
    What is this for please?
    Is it OK to leave it?
    Thanks.
    Regards,
    Jules.
     
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Hi, for me, it's unknown when you ask this for a original board, but I think you ask it for a clone board because as far as I can remember has an original board no u702.
    Anyways, as from the clones, u702 is not used/present on the board as you can see on this picture.
    Boards with a 7 pins security chip connectors has a 200 Ω resistor on it, the 8 pins versions not.

    Vu+_duo_u702.jpg

    Vu+_duo_u702B.jpg
     
  3. Jules

    Jules Active Member

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    Thanks JB,
    Must admit when I first saw this box, it din't look like a clone. But as you say it must be.
    What is the purpose this board?
    Regards,
    Jules.
     
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    It's a security chip, but actually rather a decoding chip.
    Only the clones have these like this way, with an connector, or soldered to these pins.
    More about the symptoms when it's not working you could see here,
    Frontpanel, only red led or stuck on Starting.
     
  5. Jules

    Jules Active Member

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    Thanks again JB.
    Funny you should show that.
    This box had red light fault so replaced cap 807 and all worked.
    Had it on for about 40 mins then crashed and went to display
    showing "starting".
    Looking for swolen caps on psu but none obvious.
    Could be that security chip?
    I'll do some more digging and keep in touch.
    Regards,
    Jules.
     
  6. Jules

    Jules Active Member

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    Just another thing,
    I did notice there was a little bit of corrosion around the security chip.
    I cleaned it up before this fault appeared though.
    Maybe doing the Buck mod will cure it also?
    Regards,
    Jules.
     
  7. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Q: Could be that security chip?
    A: Could be, but only when you did some online updates, or it could be a hardware failure as bad solder near or to the security chip.
    It can also be related to heath, see if the box working when it has been cooled down.

    Q: Maybe doing the Buck mod will cure it also?
    A: It depends, normally you may only this issue when you have a 3.3v failure which of course also is the delivery voltages for the security chip.
    In any case, I would first measure the psu voltages before thinking of the buck mod.
     
  8. Jules

    Jules Active Member

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    Thanks JB,
    I have found changing caps on PSU has worked on a Duo in the past, even though there was no visible swelling on them.
    Could also be worth a go
    Regards,
    Jules.
     
  9. Jules

    Jules Active Member

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    Another thought JB,
    Is it worth changing caps 850 and 814 aswell as 807,
    or do you think that woudn't cause it to go back to "starting"
    Thanks.
    Regards,
    Jules.
     

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  10. Jules

    Jules Active Member

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    Just measured voltage coming from PSU, From the 2 3.3v outputs I am only getting between 3v and 3.2 v
    This could help?
    Cheers,
    Jules.
     
  11. Jules

    Jules Active Member

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    I have just read again and getting 3.3v
    Could be PSU caps?
     
  12. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    When you want to use the original power supply, and using the box daily, then it's the best option to recap at least the power supply.
    And yes, a bad cap can give an unstable voltages, therefore it's always better to do a recap job when the power supply has been used for a while.
    But you could start with the 3.3v circuit, just to see if it's improving.
     
  13. Jules

    Jules Active Member

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    Thanks JB,
    Will post back.
    Regards,
    Jules.
     
  14. Jules

    Jules Active Member

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    Hi JB, update.
    I have replaced the 3.3v cap and getting a stable 3.3v now.
    Also replaced 5.2v and getting around a stable 5.16v.
    Improvement! I'll let it run and see how it goes.
    Thanks. Jules.
     
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  15. Jules

    Jules Active Member

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    Hi Johnny,
    Had Duo working for over 2 hours, including playing recordings and switching channels.
    Worked 100%.
    Hopefully sorted.
    What do you think?
    Regards,
    Jules.
     
  16. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Because the 3.3v and 5v and 12v are important voltages for the board to work properly and they must provide a stable power supply, at least the 3.3v/5v for the cpu,
    Then it is very possible that the problem now after the cap replacements has been solved.
     
  17. Jules

    Jules Active Member

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    Thanks for that Johnny.
    Didn't change the 12v cap though.
    But it's working.
    Cheers,
    Jules.
     
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  18. toysoft

    toysoft Well-Known Member Staff Member

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    If the board is the old one (Ferrari v2 or v3), you could even change that board to VU J board, and be able to use Original images with the VU+ Duo Clone, could be handy.

    TS

    [​IMG]

     
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  19. Jules

    Jules Active Member

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    Thanks Toysoft, good advice!
     
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