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Results of light bulb current limiter ?

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  • #76
    I'll see what I can find. I may just strip the board ,and start over...LOL.....I checked most of the resistors last night ,and all seemed good, so I'm still not sure why I heard the arc, and the bulb got brighter. Everything so far tests good.

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    • #77
      Just a passing thought.
      When testing, make sure that you have the output transistors attached to the heat sink.
      You can not operate the amp for very long without it before they get hot & short out.
      If there are any insulators behind the transistors, they must be in sound condition.

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      • #78
        Hey Jazz,

        I do have the transistors attached to the heat sink, however I have noticed that one of the pads is torn. Could it still be leaking through? Could I use heat paste along with the pad , or should I try to replace the pads ?

        Thanks, Tom

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        • #79
          Isolation pads

          I would replace them.
          This may be the root cause of your continued grief.
          The tab of the transistors is at rail voltage (+29Vdc -29Vdc)
          The heat sink is nominally at ground potential.

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          • #80
            I'll do that Jazz...although finding them in this area could be an issue. All we have is Radio Shack... I'll get them somewhere.

            Thanks

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            • #81
              MCM Electronics
              Keyword: transistor insulator
              Link: Search results for "Transistor insulator"

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              • #82
                Thanks Jazz !

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                • #83
                  Originally posted by Jazz P Bass View Post
                  MCM Electronics
                  Keyword: transistor insulator
                  Link: Search results for "Transistor insulator"
                  Got the insulators, and back at work on the amp ......

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                  • #84
                    Ok...new pads installed ..still drawing high current with no load. very small voltage readings anywhere on the board..maybe 1-3vdc at best, and after a minute or so some smoke was visible. At least before this last issue I had low current draw with no load. LOL.....think I'll build a new board.

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                    • #85
                      Godspeed.
                      83 posts & we got nowhere.

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                      • #86
                        I know....what a pain..I'm still gonna keep at it. I appreciate all the help from you guys. I'm sure I'll be back with a different project

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