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Behringer MX2642 with stuck PFL

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  • Behringer MX2642 with stuck PFL

    Got a MX2642 Rev G that has the PFL stuck on! Been searching for schematic for this bugger but to no avail. The circuit is a bit different than all the other Rev's so making it difficult to locate the problem.
    Doesa anyone have a Rev G schematic?

  • #2
    Are ALL of the PFL led's on or just one?

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    • #3
      Just the one in the meter area.

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      • #4
        My experience leads me towards the switches. Of course it could be elsewhere too.

        You have the PFL button on each channel, plus a number in the master section. Exercise each one and wiggle it. Also check for feel, do any of them feel different?
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Agree. I don't think I've ever had a PFL problem that wasn't a switch issue.
          "Yeah, well, you know, that's just, like, your opinion, man."

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          • #6
            Got some 700 ohms on the enable line for the pfl circuit. Have exercised all the pfl switches many times. Really need a Rev G schematic of this unit as there seems to be many differences from other rev's.
            Also, I placed an external PS on the enable line, and at one point got 20ma current flowing! Seems like a bad capacitor in the enable circuit! If it is a switch, how to find the bad one?
            I know this is not the best mixer, but do not have the 350 - 500 to replace it right now.

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            • #7
              We all wish we had schematics, but in their absence we soldier on.

              So is the PFL stuck on, or is it just the PFL light stuck on? If the PFL itself is stuck on. Listen to it and go down the channels feeding each in turn with signal. Does the signa come out on any one? That might identify which channel is sticking it. Might not be a channel, so don't forget to check the stuff in master
              Education is what you're left with after you have forgotten what you have learned.

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              • #8
                Here is Rev H. (Sorry. No Rev G)
                I have Rev D1, D2, E, H & I.
                Attached Files

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                • #9
                  This is interesting! Sometimes feeding the enable line with 1.3V, the PFL light will stay off for a minute or two and audio will work as normal.
                  Other times removing the 1.3V and PFL comes on instantly. Have ohmed the enable line while while exorcising the pfl switches, but always comes back to around 500 - 700 ohms.

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                  • #10
                    solved the issue by removing D75! Did not really need PFL anyway!! Something was setting the enable line low for PFL! Maybe this G series has a capacitor in the enable line failing! Do not know as th series schems are unavailable.
                    Tried plugging into each cnannel to see if pfl worked, but no response.

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