Announcement

Collapse
No announcement yet.

soundcraft spirit m4 mixer troubleshooting

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #21
    Re: soundcraft spirit m4 mixer troubleshooting

    what does it connect to ? eg r398

    Comment


      #22
      Re: soundcraft spirit m4 mixer troubleshooting

      sorry, bottom right corner, had a 170% zoom

      Comment


        #23
        Re: soundcraft spirit m4 mixer troubleshooting

        i can see it on the pic of board but no use to me ..tell me what it connects to .?
        i am wanting to know whats its job is . i cant find it on the schematics .

        Comment


          #24
          Re: soundcraft spirit m4 mixer troubleshooting

          ok! i think you nailed it! it appears it goes to the sleeve of all outputs!!
          Last edited by 5inc; 01-04-2017, 05:24 PM. Reason: rush and excitement

          Comment


            #25
            Re: soundcraft spirit m4 mixer troubleshooting

            sorry, it took me so long because I haven't got it completely out of the case, i had to look against a light to be able to trace at the back of the board from a side

            Comment


              #26
              Re: soundcraft spirit m4 mixer troubleshooting

              what outputs ?

              Comment


                #27
                Re: soundcraft spirit m4 mixer troubleshooting

                P/B, MIX, Monitor,both left and right and mono sum.

                Comment


                  #28
                  Re: soundcraft spirit m4 mixer troubleshooting

                  still cant find it on schematics ..
                  thing is sleeve on jack sockets is generally ground .

                  Comment


                    #29
                    Re: soundcraft spirit m4 mixer troubleshooting

                    bingo ..found it ..its page up bottom left .. looks like resistor loading between AGND2 and AGND ...
                    i would connect it if lk3 lk6 arent connected

                    Comment


                      #30
                      Re: soundcraft spirit m4 mixer troubleshooting

                      am thinking someone was trying to tame ground hum .. so long as something is connected between the grounds it should at least produce sound

                      Comment


                        #31
                        Re: soundcraft spirit m4 mixer troubleshooting

                        skimming through the manual it appears these grounds are floating and not connected to the chassis .

                        Comment


                          #32
                          Re: soundcraft spirit m4 mixer troubleshooting

                          It's way past my bedtime, I'm not seeing right and starting to mess things up. I'm going to bed, tomorrow evening, with time, I'll make a few pics, try to upload them, and explain you what I have here.

                          Because as I was taking the board appart to solder that link i had a closer look at the board from behind and I saw that it didn't go to gnd, but to a resistor that isn't there, and a few other odd things.

                          see you tomorrow

                          Comment


                            #33
                            Re: soundcraft spirit m4 mixer troubleshooting

                            i must sleep too ..yes some pics will help here ..the schematics are presuming the unit is in the same place as i am ...

                            Comment


                              #34
                              Re: soundcraft spirit m4 mixer troubleshooting

                              Okay lads, I woke up early to do the homework before i get to work, here are the links to the pictures.


                              back side overlook


                              Link part(wire added thinking it had tipped off, and re-disconnected when I saw the next parts)


                              resistors missing beside cn6


                              wires to ground from r547


                              back side closeup, resistors wired to ground(extended to the screw beside JK9)


                              I also realized the two resistors on the last pic, were split in between them, where they join the green wire. I'll replace those and see, before I re join LK58.
                              With this done, I will be back at noon

                              Comment


                                #35
                                Re: soundcraft spirit m4 mixer troubleshooting

                                ok, re-connected the resistors, and now the 4 return peak leds light up :S

                                Comment


                                  #36
                                  Re: soundcraft spirit m4 mixer troubleshooting

                                  I think what needs to be done is a check on the schematic and find where these wires have been connected and try to find why.

                                  They could be to replace blown tracks, part of a legitimate conversion/mod, or some bad attempt to workaround a problem they couldn't fix.

                                  The fault you're seeing now may be related to the original fault if these wires are indeed some repair attempt.
                                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                  -David VanHorn

                                  Comment


                                    #37
                                    Re: soundcraft spirit m4 mixer troubleshooting

                                    I'm back, and it appears now the peak lights aren't staying on :S I've tried a couple outputs and it aint fine though.

                                    Ok agent, I'll do that after dinner, my turn to cook today, I'll make a little diagram of what links where and also I'll write down all the wee resistors and caps missing, and we'll see from there.

                                    Comment


                                      #38
                                      Re: soundcraft spirit m4 mixer troubleshooting

                                      ok, on one side I'm missing:

                                      LK58
                                      Resistors: 37,62,223,224,334,335,364,378,397,455,475 and 666
                                      Capacitors: 228,258,261,273 and 317.

                                      And on the other I have this extra:
                                      A link from R547/C313/TR15 to pins 5/6 of CN8.
                                      An other from C315 to gnd, (the screw beside CN8)

                                      Then CN9 pin 2, is sent along a wire through the back of the board to the next board, to a point where it should join R79/R80 to gnd, but the line that goes to gnd is cut off.

                                      On the same CN9 pins 5,6 also go through the back of the board, to c11/c18, the line going to gnd is cut off aswell.
                                      These 3 pins are gnd so they are all shorted together.

                                      4 links at what appears to be return gains,
                                      R258 to R177,
                                      R257 to R183,
                                      R264 to 189,
                                      R265 to R195.

                                      And the last is a wire that goes from the second screw at the top of the top board, trhough a 75ohm resistor to ring in L monitor out and another 75ohm resitor to ring in R monitor output.

                                      That's all I could work out for now. I don't know Who did this and why, I'll try and find out. But it seemed to work fine untill it got wet at a party. Or so I've been told.

                                      Comment


                                        #39
                                        Re: soundcraft spirit m4 mixer troubleshooting

                                        i dont have the brain power right now to start working out why someone did all that to it . best guess is grounding problems .
                                        i think its best to narrow it down into sections starting from power supply then input boards .
                                        you need a signal tracer or scope really ..

                                        Comment


                                          #40
                                          Re: soundcraft spirit m4 mixer troubleshooting

                                          yes it's late...
                                          I have the signal tracer still unused, tomorrow i'l check out what it does.

                                          Comment

                                          Working...
                                          X