An Electronic Welder Circuit Question

Discussion in 'General Electronics Chat' started by BlackMelon, Nov 30, 2015.

  1. BlackMelon

    Thread Starter Member

    Mar 19, 2015
    31
    0
    Hello,

    I'm repairing a welder. Its schematic is in the pdf file. For my doubt, I want to know about a gate driver circuit in board C. What kind of driver is this?
    (The signal measured between Red(S)-C and White(S)-C is depicted in the image file. Its peak and crest are +21.4 and -21.4 consecutively)

    Thank you
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,782
    938
    I would call it it a steering diode array. The positive half cycle goes one way and the negative half cycle goes by a different path.
     
  3. BlackMelon

    Thread Starter Member

    Mar 19, 2015
    31
    0
    Could you clarify more about its operation? In a certain mode, which switching devices are on and which are off?
     
  4. BlackMelon

    Thread Starter Member

    Mar 19, 2015
    31
    0
    According to the schematic and running a test previous, the zeners D13 and D12 and capacitors C2 and C10 had been toasted, so they are desoldered out from the circuit.

    https://www.mediafire.com/?89nyx8uxs51i00w
    Here, I've got signals of Red2(S)-C and White2(S)-C with respect to a MOSFET's source (S). For a scope settings, I checked that my ground levels of both channels were set at Y=0 on displaying screen, and signals are measured in DC coupling mode. The signals swing below 0V.
    The yellow trace = Red wire
    The blue trace = White wire


    https://www.mediafire.com/?53vf2r75x15s9qc
    What's more, this is a video showing gg and a MOSFET's gate signals respected to a MOSFET's source (S).
    The yellow trace=gate
    The blue trace = gg

    Could you please analyze its operation?

    Thank you
     
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