Vu Duo PSU no Voltage on all pins 5VS

Discussion in 'VuPlus Duo Hardware troubles and Repair support.' started by tomeek.p, Nov 22, 2017.

  1. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Ah, so it was a bad connection to the q6 center pin, good that you have found and solved it, well done. :)
    And thank you for your message.
     
  2. Layer3

    Layer3 New Member

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    Hello again!

    The receiver has booted once, but suddenly, while testing a recorded movie, it has rebooted, and it has not booted again... So I've done again the old fix with the resistor and everything works fine again... Any idea? It's quite strange...
     
  3. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    If you can give me more info of where you have placed the resistor, from/to, then I may maybe be able to see why it works this way, and not on the normal way.
     
  4. Layer3

    Layer3 New Member

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    Here you can find a picture of the connection.
    IMG_20180730_063927.jpg
     
  5. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    You have placed a resistor between the coil L1 to the 12v output circuit which is basically the same as placing a resistor on the Q6 center pin (Drain), and the 3th pin (Source).

    Q6 center pin circuit..
    The Q6 center pin circuit goes first to the jumper wire JP16, then to the JP jumper wire 14, after it to the resistors R33/34 and the Q5 pin 3, R32, C16, then to the connector CN1 3v3.
    This circuit is probally fine, so also from this Q6 center pin circuit to the D10 which is first the C12, inductor (coil) L1, D10 (2x diodes) center pin, and ends to C13.

    Q6 pin 3 circuit..
    Q6 3th pin goes to the 12v outputs and one cap, the C18.

    Since you say that it works fine with a extra resistor, but crashes without, then I think it could be some bad solder or defective Q6 FQP50N06 60V N-Channel MOSFET transistor, maybe the diode part in it.
    See here the information about it,
    FQP50N06.jpg

    You should be able to measure the Q6 with diode measurement, but I think only if you remove it, as this..

    Measurements/testing of the FQP50N06 60V N-Channel MOSFET transistor with diode measurements.

    Set your multi-meter on diode measurements.

    Place the black probe to the center pin, or heatsink (Drain) which is the same, red probe on the pin 3 (Source), measurement should be .511,
    Q6-FQP50N06-01.jpg


    To switch..
    Black probe to pin 2 (Drain), Red to pin 1 (Gate).
    Q6-FQP50N06-02.jpg


    If it works you should see a lower diode value .136 from pin 2 (Drain) to 3 (Source).
    Q6-FQP50N06-03.jpg

    Reset,
    To reset, just create a short between the pin 1 (Gate) and 2 (Drain).
    Q6-FQP50N06-04.jpg

    After the reset you should see again the .511 diode value from pin 2 and 3.
    Q6-FQP50N06-05.jpg

    If you have these measurements, or at least noticed that it switching, then you may assume that it works.
    In that case you may have somewhere a bad solder, thinking of the pin 2 circuit, or pin 3 circuit.

    If not then you may need to replace it for a new one, or keep it with the resistor modification.
    As far as I see it it can not harm, but I would just replace the Q6.
     
  6. Layer3

    Layer3 New Member

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    Hello again!

    Thank you for your help.

    Indeed I've measured the Q6, and I have these values:

    Black probe to center pin and red probe to the third pin:
    IMG_20180802_134906.jpg

    Black probe to pin 2 and red probe to pin 1:
    IMG_20180802_134923.jpg

    Then again as before:
    IMG_20180802_134934.jpg

    After the reset I have again the first value:
    IMG_20180802_135000.jpg
    So I don't have the same values as yours, but it seems to work, right?

    Thanks again!
     
  7. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Well at least it seems to give some reaction with the switching and as for the value, it could differ due the type multi meter.
    However, I'm not fully convinced that this may be good with the nowlidge that you have only the 12v delivery by using a resistor.
    Better would be to replace it, just to be sure that it's not caused due the Q6.
    Or wait till Friday evening, then I'm be able to do more measurement.
     
  8. Layer3

    Layer3 New Member

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    Hi there!

    Finally I'll change when q6 transistor... Because the weird solution is not working anymore... It starts, and suddenly it reboots and it keeps stuck in Starting....

    So I will change the transistor and I'll tell you...

    Thank you again!
     
  9. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Okay, hopefully it will solve your problem, and if not, then I think of some bad cap in the circuit as C12, C13.
     
  10. Layer3

    Layer3 New Member

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    And which kind of caps are they? I'll try to buy some tomorrow. Thanks!
     
  11. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    C12 = 100uf/25v
    C13 = 470uf/35v
     
  12. Layer3

    Layer3 New Member

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    Hi!

    Well, I've changed the transistor, and the receiver keeps stuck in starting... I've measured the voltages and now I have the 12v but it does not start.

    So no idea what to do next...

    Here is the installation I've made:
    IMG_20180820_193811.jpg
    Any ideas? Change the caps c12 c13?

    Thanks a lot.
     
  13. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Maybe is the psu now just fine but in the meantime you have get the famous c807 cap issue.

    [​IMG]
     
  14. Layer3

    Layer3 New Member

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    Ok, I will try it tomorrow... Thanks again!
     
  15. tonydix

    tonydix New Member

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    I was trying to trouble shoot my power supply which has good voltage 310 volts on the main capacitor but will not produce any volts except v5s. When I short con and v5s I get 1.1v and .01 v across opt3 cold side and when the jumper is removed I get 5v and 7.4v across the same points. Voltages across opt2 appear in line with the posts above. Any ideas ? and many thanks. Tony
     
  16. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    This seems to me a issue by the hot zone, maybe a bad power ic or bad/outdated solder or interrupted circuit.
    Nevertheless, since there are several psu versions, I need at least a picture of the power supply, preferably from both sides.

    Or else, tell me at least if it has one of these circuits on the hot zone, the print side.
     
  17. tonydix

    tonydix New Member

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    Not very good at phots but these are my best efforts. You should have seen the others ! Many thanks for any advice and happy new year
     

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  18. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I'm not sure if I have these type power supply, thus I need to check this tomorrow (Monday).
    And Happy new year to U2.
     
  19. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    The good news is that I have the same psu, which is the original, but not working.
    Mine has no outputs, only an unstable 5vS which is as I see it due a bad IC1 (NCP1271),
    Vu-Plus-duo-psu-org-IC1-1271P65.jpg


    or due the Q4 (P9NK70ZFP).
    Vu-Plus-duo-psu-org-Q4-STP9NK70ZFP.jpg

    Since I do not have this parts to fix this psu, I'm not be able to repair it for using it for the measurements.
    Thus I have no measurements from this type power supply to help you.
    But check I think at least the IC1 Drv and Vcc pin as also the Q4.
     

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