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Randall RH150 low output

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  • #31
    Originally posted by g1 View Post
    So the heatsink is still getting hot, or that was just when the wiring wasn't all hooked up?
    Since that side got hot, have you redone the diode or resistance checks like in post #17 ?
    When the wiring was hooked up properly, 1/2 of the heatsink(the side that I didn't replace, that we determined good, I believe) got hot, but the side that I replaced the 2 Mosfets did not get hot.

    Here are my current resistance readings from the junction of D3 and D5 to the pins of the Mosfets:

    TR2
    1 - 750K
    2 - .3
    3 - 1M

    TR1
    1 - 750K
    2 - .3
    3 - 1M

    TR6
    1 - 800K
    2 - .4
    3 - 1,4K

    TR5
    1 - 800K
    2 - .4
    3 - 1.4K

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    • #32
      Can you post DC voltages for those same pins on the four output Fets. Try not to let it get too hot, if you have to, just do a few at a time and let it cool between.
      Originally posted by Enzo
      I have a sign in my shop that says, "Never think up reasons not to check something."


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      • #33
        Originally posted by g1 View Post
        Can you post DC voltages for those same pins on the four output Fets. Try not to let it get too hot, if you have to, just do a few at a time and let it cool between.
        Yep here they are :
        TR2
        1 50
        2 52
        3 53
        TR1
        1 50
        2 52
        3 53


        TR6
        1 50
        2 52
        3 -53
        TR5
        1 50
        2 52
        3 -53

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        • #34
          By those readings, TR1 & TR2 are the ones that should be hot, TR5 & TR6 are not turned on.
          Are all the .1R 5W still good?
          Originally posted by Enzo
          I have a sign in my shop that says, "Never think up reasons not to check something."


          Comment

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