Duo low signal

Discussion in 'VuPlus Duo Hardware troubles and Repair support.' started by Jules, Sep 4, 2017.

  1. Jules

    Jules Active Member

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    Hi Guys,
    You all have helped me with PSU issues on a clone Duo - thanks.
    I have another problem with my genuine Duo.
    I am getting low signal on many channels, hopefully it is just caps, because when I first switch on the signal is better but soon reduces.
    Have already replaced C848 which improved slightly but still not good.
    Any more help would be greatly appreciated.
    Thanks,
    Jules.
     
  2. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I'm thinking of the inductor L301 near the 54.000 crystal which is sometimes bad and may give this issue.
    But I also thinking that you may find it with cold spray (ice spray) because you say that it's when it is cold works.
     
  3. Jules

    Jules Active Member

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    Thanks for the reply Johnny,
    Yes, when I first switch on the signal not fantastic but good.
    After about an hour it reduces, do you think caps?
    I already changed C848, I have just now changed 837, 852, and 819. I am just about to try.
     
  4. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yes it's possible that it may be a cap issue, but it's difficult to say which, therefore I always use ice spray to see which cap reacts.
     
  5. Jules

    Jules Active Member

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    Thanks Johnny, no freezer spray at the moment.
    OK, after changing the caps mentioned above, signal is quite a lot better, getting around 70-80% on most sats with my 1.2m gregorian dish. Still seems to fluctuate slightly. Could need more caps changing, really need to get more spray. Do you still think it could be the inductor? Also are they easyenough to find a replacement one?
    Thanks,
    Jules.
     
  6. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yeah, it could be but mostly you can see it on the color it have, by doubts I replace them mostly from a spare motherboard.
    As for the uH value of it, this I could give you not earlier than wednesday because then I'm back in my workshop.
     
  7. Jules

    Jules Active Member

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    Thanks, Johnny, appreciate that.
    Regards,
    Jules
     
  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I've compared it from two boards and the L301 inductor value gives here 2.950 uH.
    Other notes from my suggest that these inductor only need be changed if the coil in it is dark colored or is sensitive with the signal when it's measured on the coil with vdc measurements.

    It's better to remove/replaced it with two solder irons, with hot air this coil may get damaged.
     
  9. Jules

    Jules Active Member

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    Hi Johnny, thanks for getting back to me.
    I have been trying it after changing the caps, signal seems a lot more stable and staying between 60 and 80% depending on the sats.
     
  10. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Well done, glad to read that the caps change has improved it.
    After all, It's mostly not a easy fault to solve.
     
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  11. Jules

    Jules Active Member

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    Thanks Johnny,
    I was thinking of changing more caps also but not sure which other ones would affect it.
    While signal is good I will leave for now.
    Regards,
    Jules.
     
  12. Jules

    Jules Active Member

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    Hi Johnny,
    Seems tuner B is getting low signal again on HD channels after a liitle while.
    Tuner A is still fine though. More caps I suppose?
    Cheers,
    Jules.
     
  13. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Since you have some success with caps replacing it seems to me most likely, maybe the two caps near the u803 lnb supply and control ic.
     
  14. Jules

    Jules Active Member

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    Thanks Johnny, I will let you know.