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H-brige on fire - I changed parts - but what now?

Discussion in 'Off Topic - All other stuff here' started by HAVOG, Jan 27, 2009.

  1. HAVOG

    HAVOG New Member

    Joined:
    Jan 2, 2009
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    Occupation:
    High and Low voltage technician, production automa
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    Denmark
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    Hi

    One of my mosfets xploded after testing it... to the max obviesly.

    I changed mosfets, 74HC08 IC, BC546s, z-diode.

    But CH1 Green Led comes on when I connect the Driver to 12VDC. It should not do that, right?
    I have no load or AVR attached. And I wont connect them until i know what is wrong. Don't want fire again.


    Please help.

    Henrik
    HAVOG, Jan 27, 2009
    #1
  2. egoexpress

    egoexpress Active Member

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    Sure that all parts are mounted right (+/-), and you dont have any shortcuts in your circuit? PLus and minus connected properly to the h-bridge?

    Regards
    Christian
    egoexpress, Jan 27, 2009
    #2
  3. HAVOG

    HAVOG New Member

    Joined:
    Jan 2, 2009
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    Occupation:
    High and Low voltage technician, production automa
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    Hi, Thanks for your reply.

    It worked before the mosfet xploded. I connected the power right - i'm not totally stupid, hehe :lol:

    The mosfets, the bc546 and the 74HC cannot be places wrong. And the zener turns same way as the old one.

    The reason the green led comes on is that the channel is open, right??

    A short circuit could be caused by a burnt component, but I don't know which...


    Henrik
    HAVOG, Jan 28, 2009
    #3
  4. tronicgr

    tronicgr

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    Hi Havog,

    Most of the times, when an h-bridge leg explodes, it takes down its pair that is placed crossed. You can see in the next photo the pairs being circled in the same color.

    dual_simple_hbridge_1_2b_photo_xplode_pair.gif


    Or, perhaps you may want to use a mosfet tester to find what other mosfet was affected:
    http://www.x-simulator.de/forum/post12552.html#p12552

    Regards, Thanos
    tronicgr, Jan 28, 2009
    #4
  5. HAVOG

    HAVOG New Member

    Joined:
    Jan 2, 2009
    Messages:
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    Occupation:
    High and Low voltage technician, production automa
    Location:
    Denmark
    Balance:
    299Coins
    Ratings:
    +0 / 0 / -0
    Hi again

    I tried to make some measurements on my bridge.

    This is what i found out.

    CH1 Minus -> A or B = 12V
    CH1 Minus -> C or D = 0V

    CH2 Minus -> E or F = 12V
    CH2 Minus -> G or H = 12V

    Maybe this can help some brainiac help me.

    Thanks

    Henrik

    Attached Files:

    HAVOG, Jan 28, 2009
    #5