Quick help with Rangemaster Clone power

Discussion in 'Burnt Fingers DIY Effects' started by milocj, Sep 14, 2015.

  1. milocj

    milocj Friend of Leo's Ad Free Member

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    I bought a kit for a slightly modified Rangemaster clone and am having a couple of issues with it, though I think I have it figured out and would like either confirmation or a slap on the wrist if I'm wrong.

    It came with a couple of different NPN resistors (verified by looking at data sheets) and the attached section of the instruction sheet also says negative ground and shows the polarized caps with the negative side to ground.

    When I try plugging it in I get a horrific buzz and almost no signal as if the ground were hooked up wrong on a guitar. If I plug a cord into the input with the battery I get the LED to turn on and off with the switch. I know there are multiple ways to hook up these stomp switches and have never seen this method, but when I try to trace it out in my head it seems that the LED comes on when the pedal is switched to bypass. If I put a power supply to the jack I get no LED in either position.

    After going through this for a couple of hours over two days I think that the wiring shown to the supply is actually for a positive ground PNP set-up and I need to reverse this. I was just going to jumper the battery clip in and bypass the 9V adapter jack but want to make sure that I'm either correct, or won't smoke anything if I'm wrong as I don't see any protection diodes.

    Thanks.
     

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  2. Anode100

    Anode100 Friend of Leo's

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    Looking at your picture, the DC jack itself is still wired for positive ground.

    Looking at the DC jack, the largest tab is always ground.

    With the largest tab to the left, the lower, middle tab is battery, and remaining tab is the power to the board.
     
  3. Anode100

    Anode100 Friend of Leo's

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  4. milocj

    milocj Friend of Leo's Ad Free Member

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    Thanks,
    That's pretty much what I thought but I wanted to make sure that this wasn't a way to supply negative ground supply that was just an oddball wiring method, just like there's so many ways to wire a 3P2T stomp switch which was also a unique way on the supplied layout that came with the kit.

    I switched the power supply around and now the LED works with battery or wall supply, plus I can actually get the correct bias set on the transistor, but I still have the exact same hum issues with just a hint of guitar signal in the background.
     
  5. milocj

    milocj Friend of Leo's Ad Free Member

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    One more question that hopefully somebody can answer: If the layout I was sent is actually showing positive ground power supply for an NPN transistor, what would be the most likely component to fail when I fired it up the first time?

    I'm still assuming I possibly did something wrong and the diagram is correct, but I now have the same symptom with the loud buzz like grounding your guitar cord when it's unplugged.
     
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