No announcement yet.

MM 135 - Little Power at Gun Tip

  • Filter
  • Time
  • Show
Clear All
new posts

  • MM 135 - Little Power at Gun Tip

    MillerMatic 135.

    Haven't used for 2 years.

    Plug in, turn on, fan works, wire feed works, set amperage 2, 6, 10 to test.

    Result: Very little power at gun tip. Sparks maybe 1/8" at intended weld site when wire is touched to weld site, wire does not melt/adhere to weld site, if wire is left on weld site with trigger depressed, the wire turns red. The different amperage settings have no impact on results except at higher amerages wire feed increases.

    I have removed the housing, blown out the inside, checked connections and visually inspected connections and components for obvious damage.

    The voltage potentiometer is functioning ok.

    Made changes suggested by Kevin and beamwalker.

    Now Thermal Overload light goes on when depressing gun trigger.

    What do you think??
    Last edited by GaryDG; 07-21-2012, 01:04 PM.

  • #2

    First thing I would suggest you do is to make sure you have a clean, correct size contact tip in the gun. If that is good then considering how long this unit has been sitting I would start by pulling the gun out of the housing and cleaning the brass pin as well as the aluminum housing itself where the brass pin slides in. Some emery cloth or a scuff pad works well for this. Inspect the connections on both ends of the work cable and look at the clamp as well.

    If this does not help then I would hook a volt meter across the output studs (the + and - studs right above the drive housing) set it on DC volts and pull the trigger to see what you have for output voltage, this should be roughly between 16 and 26 volts DC depending on where the voltage control knob is set. If you are within this range then leave the meter hooked up and try to make a weld. Keep an eye on the meter when you do this and see what happens with the voltage. If the voltage goes away (less than 10) when you try to weld the issue is inside the unit, if the voltage stays when you try to weld and you can't get a decent arc the issue is outside the unit (bad gun, work cable, clamp, etc) most likely some kind of a poor connection in the weld circuit.
    Kevin Schuh
    Service Technician
    Miller Electric Mfg. Co.


    • #3
      almost sounds like your ground is not good. i have that problem i just take grinder clean up where your grounding to and wire brush the clamp itself. if the wirefeeds dont get electricity flowing like it needs to what you just described will happen


      • #4
        Update - Thermal Light Goes On

        I followed most of the advice of Kevin, and beamwalker - thanks to you two!

        I did grind the weld sample to get it clean then filed the ground clamp as both were corroded.

        I replaced the tip and nozzle with new and cleaned the contacts inside the gun.

        Kevin refered to "pulling the gun out of the housing and cleaning the brass pin as well as the aluminum housing itself where the brass pin slides in" - maybe my gun is different to what he referred to - when I open the gun the only thing to clean were the contacts - which were dirty.

        Now, when I turn on the MM and pull the trigger, the Thermal Overload light goes on.

        I think the Thermal Overload Switch is good since if I disconnect it the Thermal light goes on when I turn it on.

        Any ideas?