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  • #1 by Trimitsos on 14 Apr 2017
  • I have potentially fry up my new Vtx...
    I connected 14V power on the 5v output of the Vtx by mistake....
    this is what happens if you insist making soldering late at night, while being tired!!!
    So now it doesn't power up at all....

    The only part that looks burned is this one with number "14".
    Does anyone know what is this?

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  • #2 by Trimitsos on 16 Apr 2017
  • Anyone that knows this part??? please some help here... :help: :help: :help:
  • #3 by hoverfly on 17 Apr 2017
  • I would have said it's a resister. However i have looked at a t/x i have and the same part is marked l4f  and lt usualy denotes a choke.
    Not a lot of help i'm afraid but it's more than likely that a semiconductor has blown and this would not be visible.
  • #4 by Trimitsos on 21 Apr 2017
  • I would have said it's a resister. However i have looked at a t/x i have and the same part is marked l4f  and lt usualy denotes a choke.
    Not a lot of help i'm afraid but it's more than likely that a semiconductor has blown and this would not be visible.

    Could anyone else give an idea???
    can I measure it somehow?
  • #5 by atomiclama on 21 Apr 2017
  • Where is it in the circuit?

    Input / output.

    Can I have a picture of the whole board? Both sides.

    Might be a diode on the input, reverse polarity protection.
    Or some other type of protection.

    Can you measure it's resistance? if open circuit it may have blown.

    If you are then feeling daring you could just short it out and see.

  • #6 by hoverfly on 21 Apr 2017
  • On mine as above it's on the neg rail of the 5 volt output, other side is the socket... Mine died after the aeriel got removed in an unplanned arrival.

  • #7 by atomiclama on 21 Apr 2017
  • #8 by hoverfly on 21 Apr 2017
  • That would make sense,  Trimitsos says the whole board is dead.
    Just checked mine , It's  a diode. (or was) :cry
  • #9 by Trimitsos on 21 Apr 2017
  • Can I have a picture of the whole board? Both sides.

    Can you measure it's resistance? if open circuit it may have blown.

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    I tried to measure resistan, and the result is:
    connecting the poles of my meter one way I get 0 resistance
    reversing polarity of my meter I get infinite resistant.

    THough, the same does not apply for the nearby part that looks identical, and in better condition.
    In this case, with both polarities i get 0 resistance
  • #10 by Trimitsos on 22 Apr 2017
  • So is it finally a diode for sure?
  • #11 by hoverfly on 23 Apr 2017
  • So is it finally a diode for sure?
    99% sure,  it dosen't explain why the rest of the board is dead though , you could just bridge the link and see if it will work, just remember the reverse polarity protection has gone. If you replace the diode it dosent have to be a surface mount one, a standard would do.
  • #12 by atomiclama on 24 Apr 2017
  • What he said ^

    Sorry not good at debugging HW problems over the internet.

    When you measured the resistance of the dodgy diode you need to tell us which way is 0, does it match with how a diode should measure ?
  • #13 by Trimitsos on 25 Apr 2017
  • Today I received a brand new one Vtx. So it is time to compare them.

    When powering on the burned one, the coil gets hot. Where the new one has a red light glowing and the vtx plate gets worm instead.

    I replaced a diode that looked burned. Now the coil does not get worm. Instead the nearby chip gets worm, but still the Vtx plate remains cold=inactive
    and no led glows.

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    Any other ideas?
  • #14 by hoverfly on 25 Apr 2017
  • It's flocked!
  • #15 by atomiclama on 26 Apr 2017
  • Depends how much time you want to spend on it.

    Keep it for spares.

    If you have a 5V source you could connect that to the 5V rail on the VTX and see if that powers up. Remove the inductor and the 8 pin chip first. If that works then buy a small SMPS from e-bay for a couple of quid and use that to power it.

    But who knows what else maybe bust.
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