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soundcraft spirit m4 mixer troubleshooting

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    Re: soundcraft spirit m4 mixer troubleshooting

    good one, I'll add that to my workflow.

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      Re: soundcraft spirit m4 mixer troubleshooting

      tadaaa and finally I got to r266, that is reading 6kohms, when it should be 10ohms. the one beside it r267 has been replaced, and they are both the V_MASTB_L.
      I imagine that may buy me monitor outs, but I reckon phones will still have something funny in them.

      won't be back to civilization till sunday ev. so I can't do much more now appart from looking for more bad resistors or whatever my dmm can tell me.
      wish me luck.

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        Re: soundcraft spirit m4 mixer troubleshooting

        resistors fail high so i guess you measured in circuit ? unsolder one leg for proper testing .

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          Re: soundcraft spirit m4 mixer troubleshooting

          well... the resistor was bad, it split in half when I unsoldered it. I found an other hat looks just the same, put it in, and what do you know! I now have monitor outputs!

          But phones are still quite fizzy, i probed around that section the opamps ic22 & ic23 and nothing. voltages at V+ and V- were around 13.5Vdc -14.1Vdc, so they are being powered, but it appears ic23 has a negative voltage leak of -13v into it's b-side and that's what's still messing things up (I hope so, tested voltages at other ics and this is the only one that does that)

          good night.
          Last edited by 5inc; 01-14-2017, 06:55 PM. Reason: been corrected

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            Re: soundcraft spirit m4 mixer troubleshooting

            and about resistors fail high, the devil resistor 666 was 10 ohm, and half burned is now 7,5 ohms out of circuit.. I am changing it though when i get home, plus a few more. And the opamps.

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              Re: soundcraft spirit m4 mixer troubleshooting

              Carbon is conductive. Maybe the reason the resistance went down is that you are now measuring the original 10 ohms resistance in parallel with the burnt paint etc which will cause an overall lower resistance.

              Opamps are running from AC? That doesn't seem right.
              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
              -David VanHorn

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                Re: soundcraft spirit m4 mixer troubleshooting

                oops my bad that was VDC

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                  Re: soundcraft spirit m4 mixer troubleshooting

                  Hi,
                  I have the soundcraft M4 mixer
                  https://ibb.co/ncxb50
                  , but the referred schematic does not seem to apply for mine.
                  By reading the names of the resistors for the power supply board, i cannot trace the components of my board.
                  and it is a burnt resistor https://ibb.co/jP4Ok0
                  that i would like to identify in order to replace it.
                  It is R45.
                  Would it maybe be possible for someone to tell me the value of it?

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                    Re: soundcraft spirit m4 mixer troubleshooting

                    I don't suppose you've considered snapping a photo of the power supply, have you? At least of the area this burnt resistor's from?

                    And if this is toasted, odds are whatever's connected to it might not be in the best of health either, so... It would be a risky potential-waste-of-time to replace this resistor and have it burn up again, y'know?
                    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

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