first welds with my '70s Airco Heliwelder AC/DC - uh oh

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A young man I know came over for a MIG welding lesson today. Except when he got here he said no, he needs to learn stick. Well, I hauled home an Airco Heliwelder AC/DC a few days ago so I set it up as best I could and we welded with that. It welded just fine on several kinds of rod. But the current setting wasn't right. Not at all. Running 1/8" 7018 in the middle amperage range I had to turn it almost all the way up to make it weld right. That should be near 250 amps. Obviously, it was more like 120 (since that's about where 1/8" 7018 likes it). Stumped, I read the manual. Now I'm wondering - if it's set up in half-wave mode (I haven't checked yet) would that explain the output current being off by about a factor of 2 from where the knobs say it should be?metalmagpiePS This welder was made by Miller in the late '70s. It's just like a 330 A/BP.
Reply:I would look at what voltage it is set up to run at. It sounds like it is set up for 480v and is being run on 240v. There should be a schematic on the inside of the door that covers the power lugs. You move the copper jumpers around to match the voltage needed.
Reply:Were you running it on ac or dc. If ac try dcep 7018 doesn’t like ac with locv or try 7018 Ac rod
Reply:

Originally Posted by thegary

I would look at what voltage it is set up to run at. It sounds like it is set up for 480v and is being run on 240v. There should be a schematic on the inside of the door that covers the power lugs. You move the copper jumpers around to match the voltage needed.
Reply:Was running DCEP. Thanks!metalmagpie
Reply:After digging into it, I can now answer my own question. No, the half wave balance configuration isn't responsible for the weird current readings. Because my welder doesn't even have the half wave setup. End of story.metalmagpie
Reply:Have you blown out all the trash inside the welder, and/or run all the adjustments back and forth a few times to scrape off all the bees' nests and barnacles, the same way you do with a crackly volume knob on a radio?
Reply:I blew out the dust. For a welder of its age, it was remarkably clean inside. There aren't many current "adjustments", just a big potentiometer (fine current setting) and a 3-way switch (coarse current setting). I certainly moved those a fair amount yesterday. I am familiar with crackly pots from working on guitar amps. I will try squirting a little DeOxit under the wiper and see if that helps things. Thanks!metalmagpie
Reply:Do you have the two standard/remote switches set on standard or remote?They need to be set to standard when not using the foot pedal because if set on remote you will only get low end of that range of that selector position.Also their should be a Balance Resistor switch top left side under the lower front flip up cover , it needs to be set to Metallic for stick welding.Last edited by kioti; 03-24-2019 at 10:53 AM.
Reply:

Originally Posted by kioti

Do you have the two standard/remote switches set on standard or remote?They need to be set to standard when not using the foot pedal because if set on remote you will only get low end of that range of that selector position.Also their should be a Balance Resistor switch top left side under the lower front flip up cover , it needs to be set to Metallic for stick welding.
Reply:

Originally Posted by kioti

Do you have the two standard/remote switches set on standard or remote?They need to be set to standard when not using the foot pedal because if set on remote you will only get low end of that range of that selector position.Also their should be a Balance Resistor switch top left side under the lower front flip up cover , it needs to be set to Metallic for stick welding.
Reply:

Originally Posted by metalmagpie

Nothing to lose, right?metalmagpie
Reply:Did it weld right at the little house it came from. My three phase band saw came from a small house because the guy bought it because his buddy said you can just reword it to workMillermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:

Originally Posted by kioti

If you haven't verified the input voltage as mentioned earlier nothing to loose other than 2-3 minutes it takes to open the rear cover and double check the jumper links.
Reply:

Originally Posted by farmshop

Did it weld right at the little house it came from
Reply:recently purchased (ithink 70,s ) airco heliwelder 250 its not a rebadged miller.bfrom what i can find out it was made by MID-STATES and may have been marketed.under several brands. i found one that says Eutec- arc (probaly eutic castolina) inert gas welder Magna-Trans 301.if not indetical, real close.if anyone can share some  info and go to places i would greatly appreciate it, thanksgivings
Reply:

Originally Posted by metalmagpie

Arc is so smooth. It's just that the current reading on the dials isn't right.metalmagpie