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Airco 3A/ Miller 330 A/BP Will Not Turn On

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  • Airco 3A/ Miller 330 A/BP Will Not Turn On

    I just recently purchased this welder, and have successfully been using it to stick weld a project. The last few times that I started the machine, I noticed a clicking sound when I threw the on/off switch that went away after startup. I went out to my shop yesterday to continue welding and the machine won't start at all. There is power to the machine, both the fuse and power switch check out for continuity. I have downloaded the manual off of this site, and it is identified as a 1974 model from the serial number. I am at a loss where to start checking other components. Any help would be appreciated.

  • #2
    Ouch. I’ve been looking for one of these but the prices have been a bit high for a machine built around when I turned old enough to drink.
    Miller 211 AutoSet
    Miller Dynasty 200 DX
    Thermal Dynamics Cutmaster 42

    "The Sleep of Reason Produces Monsters"
    Francisco Goya


    • #3
      Need your serial number to look at the correct diagrams.


      • #4
        Serial number is: HE781499


        • #5
          Does the fan run when you turn it on?


          • #6
            No fan, nothing.


            • #7
              My Helga is a 74. If you need help, Wayne, like you need to see how something is supposed to go if his is all catywhumpous inside, I can crack the old girl open and take a peek.

              The clicking is probably the relays in there doing what relays do. You need to start by physically checking the line power at the machine. I hope you have her on wheels stout enough to carry that girth and can pull her away from the wall. Open that hatch on the back and check those wires.

              You said you checked the continuity at the fuse, there might be two fuses, so look again please. Also, in addition to the power switch there is the primary overload breaker on the front panel of the machine. Check that please.

              She’s an old girl, so my hope for you is it’s just a corroded and broken switch.


              • #8
                Ryan, thanks for your input. I checked line power to the machine which is all good. I also reset the primary overload breaker by switching it off and on again. Is there a possibility that the breaker is bad? My hope is that I didn't just buy an 800+ lbs boat anchor!


                • #9
                  You’ll need to open the old girl up and check for power on that breaker. You’ll need a DMM. Several of us have had our hands inside those old machines and should be able to help. Some of the really sharp electronic guys will be way more help than me, that’s for sure. But seems we have the same model and that might help if you have to start getting into the components.

                  We just need to make certain that you’ve checked the simple things adequately first. I’m not sure what switches would keep that machine from coming on if they were to fail other than the main power toggle and primary overload. I’ll have to go out to the shop and flip the primary overload off and see if it actually keeps my machine from powering up. I’ve never tried it. I’ll report back in a bit.


                  • #10
                    Originally posted by PJD123 View Post
                    No fan, nothing.
                    Ryan, thanks for the offer. I think he's going to find this one pretty easily........


                    OK, if there's no fan, this is going to be a pretty easy problem to solve (...he said hopefully....)

                    First, are you comfortable working around voltages that can kill you? Need all the safety precautions, like one hand in your pocket at all times--never two hands in hot circuits--arm to foot current is much better than arm to arm--right through your heart! And best to use your right hand, even if you are left handed--keeps the current path as far from your heart as possible. Use leads with alligator clips, at least one of them, and if you have trouble reaching a connection, turn off the power at the wall box, connect, and turn it back on. Wear eye protection in case of flying molten metal from an arc just in case a wire or test lead slips and causes fireworks.

                    You must have either a bad main switch/breaker or a bad connection somewhere. If you look at the schematic diagram on page 20 of the manual, upper left corner, you will see the line power comes in, and goes down to S1, which is the power switch. Power then goes through whichever jumpers are installed to select the proper operating voltage, and feeds over to the fan (FM, for Fan Motor).That's it. A switch, a couple of jumpers, and some wire. The clicking you heard was the relays further down on the left side of the diagram because they weren't getting enough power to pull in properly from wherever the bad connection is.

                    (Power to actually strike the welding arc is fed through the two contacts labeled "W" to the right, but if the fan isn't going around, no need to troubleshoot in that direction.)

                    With the switch ON , check the AC voltage between wires 38 and 16 at the switch. (I think those are the correct numbers--the print I have isn't all that clear). With power on, you should have zero volts or very close to it if the switch is conducting properly. Next, do the same thing on the other side of the switch, on wires 14 and whatever the last wire number on the switch is--I can't read it--might be 50? 80? Anyway, it's the only one left. Once again, you should see zero volts or very close to it. If you get anything other than zero/very low in either case, you have a bad power switch. If not, just start following the wires and find out where the bad connection is. Check screws/bolts for tightness, pull on crimped connections if there are any, etc. There is a bad connection somewhere.


                    • #11
                      Aeronca41 and Ryanjones2150, I will definitely do your checks later today. I really appreciate your help! Does it rule out the power switch because I already checked it for continuity when turned in the on position? Is there a way to check the primary breaker?


                      • #12
                        Originally posted by PJD123 View Post
                        Aeronca41 and Ryanjones2150, I will definitely do your checks later today. I really appreciate your help! Does it rule out the power switch because I already checked it for continuity when turned in the on position? Is there a way to check the primary breaker?
                        Sometimes you will see continuity on a switch that still will not carry power--if the contacts inside get pitted and little "stalagtites" form, the little point will pass a continuity test but there is not enough surface area to carry current. Not a common happening, but I have seen it, I would also bypass the fuse with a piece of wire for a very quick test--I have seen fuses ohm out OK and still not pass current....only a couple of times in 50+ years, but it does happen. Or, just check for voltage drop across the fuse. One lead on each end, and you should see zero.

                        That's why I had you do voltage checks across the switch---if the resistance internally is high when trying to carry current, it will show up as voltage drops across the contacts. Should be virtually no resistance, and therefore no voltage drop across the switch. Same thing with the primary breaker--you will have to take the cover off of the box, exposing a lot of power, but with the welder on, measure between the incoming feed line to the breaker box and the output terminal of the breaker. Again, you should see zero or nearly zero volts. May take some trial and error to find out which feed line goes to which terminal out of the breaker. Just pick a pair, and if you see 120 volts, either the breaker is bad or you have the opposite sides of the line. Just move one meter lead to either the other input feed line or the other breaker terminal. If you still see something other than zero, the breaker is bad. Again, remember one hand at a time and an alligator clip for the other terminal. I know an electrician who got brain damage and ultimately died using a meter like he had thousands of times before and something failed--bad test lead or something--very sad case. One hand at a time.


                        • #13
                          If it gets down to needing a new fuse, give a shout, I have some. It’s not the same screw in fuse you’ll get at the hardware store. Those are slow blow, that’s not what you want.

                          But I told you the really sharp guys would chime in and be able to help you!


                          • #14
                            So the machine with power on and run with the primary overload breaker open or closed.


                            • #15