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Testing solid state amps

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  • Testing solid state amps

    Hello,
    I have a quick question. I'm working on fixing a mackie sub power amp module. I only have the the electronics at my shop (easier than carting a customers sub around) I'm used to working on tube amps where I know I have to have a load hooked up to test things.
    Do I need the speaker hooked up to check voltages after I fix it or can I power it up with no load and be ok?
    Thanks

  • #2
    What is the model number of tha Mackie?
    Generally speaking, most SS amplifiers do not need a load for initial power-up testing.

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    • #3
      Testing ss amps..

      Originally posted by Jazz P Bass View Post
      What is the model number of tha Mackie?
      Generally speaking, most SS amplifiers do not need a load for initial power-up testing.
      I would agree with jazz bass...once the amp as been repair and cold checks have been done, next power up the unit via a lamp limiter lead connected to the amp and if all is well the lamp will flash as the amp is turned on and say off. but if there's a heavy short the lamp will stay bright. There should be low off set volt at the out of the speaker out put end with no load on say.. is the mackie you have switch mode power supply or transformer standard power supply? s/mode power supply's don't like the lamp test..

      you can use high power dummy loads and a scope to test ss amps just like valve amps that you work with.
      Experience comes with more understanding

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      • #4
        It's a Mackie SWA1801 Sub. It has a standard transformer power supply. The main amp board had a number of components go bad. The power supply section of the amp seems to check out ok. I'm in the process of testing and replacing the bad components of the amp board. I do have a lamp limiter that I use for building and fixing tube amps.
        Thanks for the info!

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        • #5
          Do you have a schematic?
          Here is the SWA 1501 if that will help.
          Attached Files

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          • #6
            Already got a schematic from mackie. Thanks anyway

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            • #7
              How far did you get with the repair? is all going to plan...
              Experience comes with more understanding

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              • #8
                Just finished the repair. Powered up and runs great. It felt pretty good to get it up and running. It was a mess when it came in. Burned out components, burned up traces.
                I've never dived this far into a solid state amp before. I'm more at home with tubes

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                • #9
                  How did the speaker sound? being that the driver it direct linked to the power amplifier no relay between then to cut it, so if the amp does the speaker get it some time's... if all is running time for the real test and hammer it hard....
                  Experience comes with more understanding

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                  • #10
                    All I had at my shop was the amp unit. The customer is supposed to bring his sub cabinet to the music store I'm doing repairs for so I can check the speaker and put it back together and give it a real workout.
                    To test it at my shop I hooked it up to one of my speaker cabs and run it for awhile.
                    I'm anxious to see how it works when put to the test.
                    That's the reason I want the customer to bring the cabinet in, to check the speaker & make sure it's ok.

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                    • #11
                      Originally posted by tonepumpamps View Post
                      Already got a schematic from mackie. Thanks anyway
                      Can you post the schematic for future reference?

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                      • #12
                        SWA1801_Input_board.pdfSWA1801_IEC_board.pdfSWA1801_Amp_board.pdf

                        Here are the schematics for the mackie sub

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