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Kent Trem Tone DR-19-A widowmaker amp conversion

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  • Kent Trem Tone DR-19-A widowmaker amp conversion

    Hello! My job today is taking one of the worst amps ever and seeing how good (and safe) I can get it. I’m building an entirely new power supply in a separate chassis which will mount on the bottom of this amp with a 1:1 iso transformer, a fuse, full wave rectifier (duh!) and new filter caps. Looking for some advice from those who have updated these, and I have a question specifically about the “on” switch on the tone knob. The hot (black) wire from the 3 prong cord will go to the fuse and then across the fuse will be wired to the original ac main line going to the switch. The other lug of this switch is jumpered to the volume pot and then to ground. Should this connection be rerouted to the primary of the iso transformer? My confusion is mostly about how to reroute the power switch wiring correctly while insuring that when the power is “off” that no mains voltage is going through to the iso transformer when the amp is plugged in. Does that make sense? Thank you!

    Here is a link to the schematic of the amp in this discussion: https://el34world.com/charts/Schemat...t/Kent5999.pdf

  • #2
    Would love some info about the switch routing

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    • #3
      If you want no voltage getting through the iso when power turned off, you need a power switch on the primary side of the iso.
      I don't particularly like power switches on volume or tone pots anyway, they can add hum.
      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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      • #4
        The only way I was able to kill induced hum from a volume pot/power switch was to wrap the mains feed with copper tape and shrink wrap over it as it ran directly over the preamp.

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        • #5
          Odd tone control. What’s this thing sound like?

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          • #6
            Originally posted by drewl View Post
            The only way I was able to kill induced hum from a volume pot/power switch was to wrap the mains feed with copper tape and shrink wrap over it as it ran directly over the preamp.
            Ugh I might just put in a nice power switch then

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            • #7
              Originally posted by drewl View Post
              The only way I was able to kill induced hum from a volume pot/power switch was to wrap the mains feed with copper tape and shrink wrap over it as it ran directly over the preamp.
              Originally posted by olddawg View Post
              Odd tone control. What’s this thing sound like?
              Sounds bad!

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              • #8
                Is there any right way to convert these things? I finally finished the new power supply and the 50C5 is cooking.. probably too much. I need to tweak it tomorrow but man, I will never work on one of these again. Sounds like crap. Well, it is crap, but has anyone here made them “not crap”?

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                • #9
                  Worst of all is the isolation transformer is installed and I STILL got shocked..

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                  • #10
                    Originally posted by Steelwitch View Post
                    Is there any right way to convert these things? I finally finished the new power supply and the 50C5 is cooking.. probably too much. I need to tweak it tomorrow but man, I will never work on one of these again. Sounds like crap. Well, it is crap, but has anyone here made them “not crap”?
                    Well yea there is. Shows some pics, All the 50c5's I've messed with(audio outputs on AA5 radios) were hot enough to burn.

                    nosaj
                    soldering stuff that's broken, breaking stuff that works, Yeah!

                    Comment


                    • #11
                      Originally posted by Steelwitch View Post
                      Worst of all is the isolation transformer is installed and I STILL got shocked..
                      Please clarify, With the ISO installed you should no longer get shocked playing the guitar(I can sometimes feel it in my fingers on a transformerless amp(flipping the power plug over usually fixes it but you cannot depend on that it needs to still be converted. Note an ISO doesnot mean you can touch the filter caps in the amp and not get shocked. All the ISO does is isolates the circuit from Mains power.
                      nosaj
                      soldering stuff that's broken, breaking stuff that works, Yeah!

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