Millermatic 350p arcing without trigger pull

admin

Hi everyone, new here, hoping someone's come across this issue: I have a Millermatic 350p, bought used about 4 years ago.  It worked fine then, used it for 2 years, then it sat covered in my shed.  Now I need to use it for some larger projects I have, but when I pull the trigger the volts drop way down and the wire will turn red and feed, but not quite melt, just bird nest on the material without actually melting.  Sometimes if I turn it off for a few hours/days then turn it back on, it will work perfectly fine for a while, sometimes hours, sometimes minutes.  I took it to a local repair place, they turned it on, it ran fine, so they blew it out and told me it was just dirty, charged me $350 and then the next day, same issues.  I tried a cable off a working 350p, same problem, so I don't think it's in the cable.When I turn on the unit, there's a loud distinct 'click' from the contactor, and you can see the little window on it, open up.  Once the wire makes the arc, there is just a 'hsssss' type sound, wire is fed and gas flows, but volts drop way down.  Pulling the trigger will speed up the wire feed, but not change anything else.I'm kind of desperate here, so any help is appreciated, thanks in advance!!Paul
Reply:

Originally Posted by paullewis511

Hi everyone, new here, hoping someone's come across this issue: I have a Millermatic 350p, bought used about 4 years ago.  It worked fine then, used it for 2 years, then it sat covered in my shed.  Now I need to use it for some larger projects I have, but when I pull the trigger the volts drop way down and the wire will turn red and feed, but not quite melt, just bird nest on the material without actually melting.  Sometimes if I turn it off for a few hours/days then turn it back on, it will work perfectly fine for a while, sometimes hours, sometimes minutes.  I took it to a local repair place, they turned it on, it ran fine, so they blew it out and told me it was just dirty, charged me $350 and then the next day, same issues.  I tried a cable off a working 350p, same problem, so I don't think it's in the cable.When I turn on the unit, there's a loud distinct 'click' from the contactor, and you can see the little window on it, open up.  Once the wire makes the arc, there is just a 'hsssss' type sound, wire is fed and gas flows, but volts drop way down.  Pulling the trigger will speed up the wire feed, but not change anything else.I'm kind of desperate here, so any help is appreciated, thanks in advance!!Paul
Reply:

Originally Posted by paullewis511

but when I pull the trigger the volts drop way down
Reply:Not more I can say to describe the situation, wire touches metal, wire arcs, but drops voltage from 26 to 8ish, so wire turns red and bendy but doesn’t melt. Gas comes on like it would if you were actually welding.  I don’t think it’s a trigger or cable issue, as I tried known working cable from working machine and had same issue.
Reply:Jack- yes volt drop is shown on display        - yes wire turns red when contacts work metal, without trigger pull, definitely not enough volts, as they’ve dropped        - with the IR thermometer, do you mean something hot internally?         -I think hiss sound is coming from inside, just not totally sure where from, but not gas.Unfortunately I’m the only guy at the shop- that’s why I’m here hahaThanks!