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Broken Spectrum 375 Plasma Cutter

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  • Broken Spectrum 375 Plasma Cutter

    I have a Spectrum 375 plasma cutter. I was cutting up some 1/8" diamond plate aluminum for the trike I'm building and the machine just stopped working. I replaced the electrode and tip, checked the voltage, verified air pressure. Took the top off and blew out the little bit of dust there was in the machine.The power light comes on after a little while when turning on the switch, the fan runs. When I click the gun I get no flow or arc. The temperature light is on but not as bright as the other lights, looks like it may be flashing really fast. If I turn down the amp rating to 0 the air flows through the tip as expected.The machine is about 3 years old. Opened the drain plug on the air filter inside, no water (have a dryer at the compressor).Any ideas? I really don't have the money to take it to a shop. I do have a degree in Electronics Engineering, Software Development and have been welding nearly every weekend now for 15 years, so taking it apart, testing and replacing parts won't be a hassle.Anyone have any schematics or service manuals available? Thank you for your assistance in advance! My kids'll appreciate the help getting the trike finished!

  • #2
    got a serial# for me?


    • #3
      Model/Serial number

      Sure, it's stock #903891, serial number LH140338P.


      • #4
        Actually in May it'll be 5 years old. Never the less you likely have a gun issue, open the handle up and check for wires touching where they shouldn't


        • #5
          Handle issues

          Must have been sitting in the showroom for a while when I bought it in Feb of '09. :s Not surprising, bought it online pretty cheap. Was new in the box.

          Anyhoo, I forgot to mention I took the handle apart at the same time I took the cover off. Didn't see any shorts, bare wires, etc.

          I sat down a couple of minutes ago and tested all of the connections (switches, wires) in the handle. Good continuity back to the unit for both the tip and trigger switches.

          Also used a tip cleaner and made sure none of the holes were plugged.

          Strange though, turned it on after checking all those connections and the Cup light came on. Shut it down, took the cup off, put it back on and now no lights at all come on when I turn the power back on. :s Seems to be sliding downhill.
          Last edited by a_edwill; 04-04-2012, 07:04 PM. Reason: Removed "Voltages". Didn't test those.


          • #6
            Broken Spectrum 375

            Contact the Miller Plasma service department at 920-735-4854. We will walk you thru some tests and help you get your machine back up and running. Or you can e-mail me at [email protected] I can send you some PC board troubleshooting information.
            Last edited by plasmaman; 04-05-2012, 08:31 AM.
            Tim Lux
            Service and Aplications Specialist
            Miller Electric Mfg. Co


            • #7
              Did you get this fixed as I have a similar problem?