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    Help identity blown part in Alesis Mixer PS

    Alesis Multimix 16 firewire
    Small capaciter is blown and I dont know the size to get, as I can't get the Service Manual Online.
    Just asking if anyone has the manual or knows what size it might be .
    Heres a photo
    Its on the leg of a 7815 Voltage Regulator.


    Thanks.
    Last edited by Carm99; 03-23-2019, 09:05 PM.

    #2
    Re: Help identity blown part in Alesis Mixer PS

    It's likely a .33µf, if on the input or .1µf if on the output
    Last edited by R_J; 03-23-2019, 09:59 PM.

    Comment


      #3
      Re: Help identity blown part in Alesis Mixer PS

      Thanks Man.
      I'll check...
      Its between the middle leg ,Ground ,and the Input ,from a 2200uf 35 volt cap.
      There was a big flame when it blew.
      Do you think the cap might have been bad to cause it to happen.?
      Cheers.

      Comment


        #4
        Re: Help identity blown part in Alesis Mixer PS

        ceramic caps randomly fail, and go short circuit.
        surfacemount ones can also fail from flexing - like if the board is dropped or bent.

        where in London are you??

        Comment


          #5
          Re: Help identity blown part in Alesis Mixer PS

          I replaced 7815 and 7915 prior to it blowing as they were bad.
          I thought that was it. It worked ok but no output on the master as if the channels outputs weren't getting sent or not being recieved.
          Im a novice really but if i can test individual parts that are bad I can change em out.
          Im repairing it to sell. Its in bits at the moment.Im cleaning it up a bit.
          Im in NW London.

          Comment


            #6
            Re: Help identity blown part in Alesis Mixer PS

            The cap value in this case is not that critical, It is mainly there to prevent high frequency noise and prevent the ic itself from self oscillating.
            If you don't want to order one, or don't have a cap meter to check values, check scrap boards and find one that is close to the size of the old one and it should work just fine.

            Comment


              #7
              Re: Help identity blown part in Alesis Mixer PS

              Ive got a meter but the cap is blown so cant be measured.
              I was thinking it might be the same as the other one on the 7915.

              Comment


                #8
                Re: Help identity blown part in Alesis Mixer PS

                PC20 & PC30 should be the same value (input to ic)

                Comment


                  #9
                  Re: Help identity blown part in Alesis Mixer PS

                  Can you please post a photo of the front of board
                  9 PC LCD Monitor
                  6 LCD Flat Screen TV
                  30 Desk Top Switching Power Supply
                  10 Battery Charger Switching Power Supply for Power Tool
                  6 18v Lithium Battery Power Boards for Tool Battery Packs
                  1 XBox 360 Switching Power Supply and M Board
                  25 Servo Drives 220/460 3 Phase
                  6 De-soldering Station Switching Power Supply 1 Power Supply
                  1 Dell Mother Board
                  15 Computer Power Supply
                  1 HP Printer Supply & Control Board * lighting finished it *


                  These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                  1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                  2 Hem Saw Computer Stack Board

                  All of these had CAPs POOF
                  All of the mosfet that are taken out by bad caps

                  Comment


                    #10
                    Re: Help identity blown part in Alesis Mixer PS

                    Comment


                      #11
                      Re: Help identity blown part in Alesis Mixer PS

                      This should fairly easy to fix as far as I can see from what I can see from the the photo that you have provided

                      I would check all the surface mount caps for shorts and check all of diodes for open or for shorts

                      I would also check all other caps for there ESR value if you have that type meter you can also check the surface mount caps as well

                      What are the parts number that are NOT LM7815 or LM2575
                      there is another part that starts with LM25–>something

                      What is the part number of PQ1

                      I hope this will help
                      Last edited by sam_sam_sam; 03-24-2019, 08:40 PM.
                      9 PC LCD Monitor
                      6 LCD Flat Screen TV
                      30 Desk Top Switching Power Supply
                      10 Battery Charger Switching Power Supply for Power Tool
                      6 18v Lithium Battery Power Boards for Tool Battery Packs
                      1 XBox 360 Switching Power Supply and M Board
                      25 Servo Drives 220/460 3 Phase
                      6 De-soldering Station Switching Power Supply 1 Power Supply
                      1 Dell Mother Board
                      15 Computer Power Supply
                      1 HP Printer Supply & Control Board * lighting finished it *


                      These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                      1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                      2 Hem Saw Computer Stack Board

                      All of these had CAPs POOF
                      All of the mosfet that are taken out by bad caps

                      Comment


                        #12
                        Re: Help identity blown part in Alesis Mixer PS

                        There are 2 LM2575's.
                        The PQ1 is BD239C.

                        Comment


                          #13
                          Re: Help identity blown part in Alesis Mixer PS

                          Please post your results of what you find wrong with this power supply
                          9 PC LCD Monitor
                          6 LCD Flat Screen TV
                          30 Desk Top Switching Power Supply
                          10 Battery Charger Switching Power Supply for Power Tool
                          6 18v Lithium Battery Power Boards for Tool Battery Packs
                          1 XBox 360 Switching Power Supply and M Board
                          25 Servo Drives 220/460 3 Phase
                          6 De-soldering Station Switching Power Supply 1 Power Supply
                          1 Dell Mother Board
                          15 Computer Power Supply
                          1 HP Printer Supply & Control Board * lighting finished it *


                          These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                          1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                          2 Hem Saw Computer Stack Board

                          All of these had CAPs POOF
                          All of the mosfet that are taken out by bad caps

                          Comment


                            #14
                            Re: Help identity blown part in Alesis Mixer PS

                            Are you still having problems with the mixer after repairiing the power supply? or are you still missing voltages?
                            It looks like they are just using .1µf caps on both the input and outputs of the regulators
                            Last edited by R_J; 03-25-2019, 05:29 PM.

                            Comment


                              #15
                              Re: Help identity blown part in Alesis Mixer PS

                              The 2200 big cap on the board is testing 0.00Ω esr.

                              Comment


                                #16
                                Re: Help identity blown part in Alesis Mixer PS

                                Are you saying the 2200µf is shorted? are you checking the esr out of circuit?
                                Last edited by R_J; 03-25-2019, 06:04 PM.

                                Comment


                                  #17
                                  Re: Help identity blown part in Alesis Mixer PS

                                  I used a MK-328 to test it and thats what it said i even reversed the leads and tested it the other way.Same thing

                                  Comment


                                    #18
                                    Re: Help identity blown part in Alesis Mixer PS

                                    Yeah.Out of circuit.

                                    Comment


                                      #19
                                      Re: Help identity blown part in Alesis Mixer PS

                                      Is the power supply working or not? As long as the cap is not shorted (check it with your multimeter (ohms) I suspect it is ok
                                      Last edited by R_J; 03-25-2019, 06:20 PM.

                                      Comment


                                        #20
                                        Re: Help identity blown part in Alesis Mixer PS

                                        Nope.No Resistance on the multimeter.

                                        Comment

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