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2 Amp power supply

Discussion in 'Repairing Electronics' started by Narmer, Apr 17, 2017.

  1. Narmer

    Narmer New Member

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    hi every one
    im new to electronics so i thought i might get good advises from this website

    i was using 12 V DC power supply 2 Amp max and i dragged too much current from it unfortune without using circuit breaker as usual
    any way the internal fuse blow up so i opened the circuit and installed new one 2 amp fuse
    the fuse did break again when powering the circuit this time so i made a jumper and notice what would happen
    i found out that the first inductor which is installed at first of the circuit in the ac line which is about 4 Micro H is heating up too much and going to smoke from heat so i switch off the circuit
    does any one knows what would be the cause of that fault in circuit
    thx
     
  2. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Burned up transformer. You likely blew the diodes the first time you overloaded it. You likely burned up the transformer winding when you shorted out the fuse with a wire jumper. Baaadd way to do troubleshooting. Fuses are there for a reason...
     
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  3. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Next time you troubleshoot something with a short, use a resistor or light bulb of the appropriate rating to substitute for the fuse. :rolleyes:
     
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  4. dave

    Dave New Member

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  5. Narmer

    Narmer New Member

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    thx alot for the informations
     
    Last edited: Apr 17, 2017
  6. Narmer

    Narmer New Member

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    thx alot for that light bulb tip , i did test the components again for voltage drops and found short but not in the first 4 bridge rectifier i found it at diode zenor 2 of them got shorted and power transistor got closed circuits at its 3 pins and small signal transistor . unfortunately cause of lake of components in my town i have tried to use some components i had from other old power circuits isnt the same exactly any way nothing to loose from trying . after replacing the old components . the circuit still have the short but the funny thing the light bulb did
    flicker after about 10 seconds of powering and kept lighting but the circuit did turn on while the short is still exist there in the same time the voltage did raise to output 17 dc volts ( usually should be 14 volts max with potentiometer ) and only small resistor i think its like 1/4 wat 100 ohm heating up . is there any logic reason why it did turn on while the short is still exist
    thx again
     
  7. Narmer

    Narmer New Member

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    another thing does any one knows how to test smps transformer out of the circuit . it has alot of inputs in the primary and alot of outputs in secondary
    i have tried to test old one i had with putting about 9 volts dc in primary and measure the potential difference if its taking any current in it
    problem that at secondary was getting like mili volts which hard to notice if its from the voltage i put at primary or from some kind of magnetic field at multimeter probs
     

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