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blender troubleshooting

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  • blender troubleshooting

    Hey all,
    I built the ROG splitter-blend and I'm getting dc voltage at the output. I don't have a ready schematic, but it's a basic opamp circuit with a blend pot at the end, and both sides of the blend pot are fed from the outputs of the opamp, through a 10uf polarized cap. I changed the caps twice, checked the polarity, etc. and I'm still seeing 4.5vdc. I tried bigger caps I had around and same thing, some small drops but not what should be, unless I'm mistaken. Any thoughts?


  • #2
    If you are using a single supply voltage (ie: 9Vdc) the opamp outputs will sit at half of the supply voltage.


    • #3
      Solved... The 1M resistor to ground at the output was missing. I realized I had just rehoused the circuit, but replaced the jack with the pull down resistor for another. Oops!* Fixed! Thanks!


      • #4
        This schematic? Splitter-Blend
        As JazzP mentioned, the op amp outputs should be at half the supply voltage. Then the caps should block the DC from getting to the pot. Sounds like there is a wiring or board layout error. Double check that the layout matches the schematic.
        "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey


        • #5
          I thought the caps should to, but even when i took the negative side of the cap off the board and just wired straight to the pot it was passing dc, and with multiple different caps. But the 1M resistor to ground solved it.