Airco Heliwelder IV contactor troubleshooting

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I searched for previous threads but couldn't  find anything specific. I just bought a used Heliwelder IV from a Vo-Tech school for $160.  They said it had been in storage for 12 years, it has a tag on it that says "Erratic contactor". I haven't got it hooked up yet, but I have opened it up and changed it over from 460v to 230v. There are manufacture inspection labels from 11/12/81 inside. It came with an FC-IV foot pedal. I've ohm'd the resistor and switch and both check good, the connector prongs looked nasty so I used De-oxit on them and they cleaned up.Recently I've been using an old Idealarc AC/DC stick welder for scratch start tig, but I haven't used a regular TIG machine in over 40 years. This is my first TIG machine and I'm looking for info on how the contactor should work and ways to isolate the problem if it doesn't or is erratic. My first plan once I get power to it is to hook up a pair of jumper cables and do a quick check for DC stick arc. If this works then I'll move my welding cables and TIG torch over to this machine. What do I need to do to test the various functions? I'm pretty sure I understand the HF off/start/continuous, HF intensity and Current panel/remote switch functions. The contactor on/remote switch I understand that the remote position will put control to the foot pedal, but what does "on" do? There is also a switch labeled "start current/weld current" with TIG sharpie above start current. I think in the start current position this would activate the start current knob next to the main current control. What I don't understand is how you want this set and it's relationship to main current. Also should the HF work without the foot pedal? Attached Images
Reply:Okay, I fired it up last night, initially it wouldn't turn on. But after cycling the power switch several times it came on and didn't have any more problem with that switch. Set all controls to panel and HF to off. Set power to mid range (max 140 amps) with weld current at 100%. Tried to start an arc with 1/8 6011 and it would spark but not really start. Set power to max and current to 50%. Arc started but was weak, then went strong and cycled back and forth. Shut down and disconnected power. Used De-oxit on contactor contacts, manually cycled contactor, then turn on with contactor in remote and cycled electronically with the foot pedal. Tried the stick again and now the arc appears strong and stable. Also tested the HF start and continous and the foot pedal for HF, all appears good. So I think I now understand the Contactor switch and that HF will work without the foot pedal. I need to swap over my welding leads and tig torch to this machine for further testing but it now appears to be worth the effort.I still don't understand what the start current is for. Do you want to set it higher or lower than the weld current? How long does it last? Is it only for use with a remote or does it matter?
Reply:Just an educated guess on my part, but it seems logical that you might need a bit more current at the start and then have it back off somewhat for the weld current as the base metal becomes heated by the weld process to reduce the chance of burn through.Sounds like you got a great deal. Wish I could score one like that.PapaLincoln Idealarc 250 (circa 1962)Lincoln Weldpak 155 w/Mig KitLincoln Squarewave TIG 175
Reply:most contactors can be disassembled pretty easy. either screws or clips on the housings.  then completely clean and smooth out the contactor plates.  there is probably some burning and arcing on the contactor plates.   I have done that on a couple and seems to help...Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Originally Posted by soutthpawmost contactors can be disassembled pretty easy. either screws or clips on the housings.  then completely clean and smooth out the contactor plates.  there is probably some burning and arcing on the contactor plates.   I have done that on a couple and seems to help...
Reply:The contact plates are a little pitted and had burn marks on the ones I could see. That's why I used the De-oxit, we use it work to deoxidize connectors all the time and it works well. I figure if it starts acting up again I'll take it out and try some emory cloth on the contacts.As for the start current I've thought it might be for higher current at the start of a weld, but I've also seen/heard of soft start on some welders. I'm just trying to understand the concept of this one. I'd like a manual for this machine but I can't seem to find one anywhere on the web. The Heliwelder IV is apparently not one made by Miller for Airco.
Reply:Oops, guess no emory cloth, I think I may still have a auto points file somewhere
Reply:start amperage lets you set a starting amperage higher or lower than the main welding current, higher will reduce or prevent sticking of the rod when starting an arc,   if you set it lower than the welding current I would guess that would be soft start.  Not sure when you would want that?  TIG maybe...  as soon as your arc is started the machine will ramp the current up or down to match the current selected on main amp control.Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Originally Posted by soutthpawmost contactors can be disassembled pretty easy. either screws or clips on the housings.  then completely clean and smooth out the contactor plates.  there is probably some burning and arcing on the contactor plates.   I have done that on a couple and seems to help...
Reply:Originally Posted by soutthpawmost contactors can be disassembled pretty easy. either screws or clips on the housings.  then completely clean and smooth out the contactor plates.  there is probably some burning and arcing on the contactor plates.   I have done that on a couple and seems to help...
Reply:Lars66But half the fun of taking stuff apart is searching all over for the little bitty pieces.I've been working on copiers for the last 12 years, I know all about losing little pieces and unplugging before working on things.  And with these welders there are large capacitors to discharge or you could get a nasty shock even with it unplugged. When I first started working on it I wasn't too concerned about them as the machine hadn't been powered up for several years and the charge should have bled off. Now if they still work properly they could be dangerous. Thanks for all the advice.Dan______________Airco Heliwelder IVIdealarc 250/250 AC/DC tombstone
Reply:Originally Posted by msgtdan. . .I still don't understand what the start current is for.
Reply:DenrepYes there is a HF intensity knob under the panel where the leads, gas, water and remote connects in. I'm assuming that the start current knob is a percentage of the range switch. I just don't know how or why you would use it and am trying to educate myself on it.Dan______________Airco Heliwelder IVIdealarc 250/250 AC/DC tombstone
Reply:Originally Posted by msgtdanLars66But half the fun of taking stuff apart is searching all over for the little bitty pieces.I've been working on copiers for the last 12 years, I know all about losing little pieces and unplugging before working on things.  And with these welders there are large capacitors to discharge or you could get a nasty shock even with it unplugged. When I first started working on it I wasn't too concerned about them as the machine hadn't been powered up for several years and the charge should have bled off. Now if they still work properly they could be dangerous. Thanks for all the advice.
Reply:Yeah, I've done some of that sort of thing in the past as well. Once used the ball out of a grease zerk as a replacement detent on a Ruger P85 safety. I will occasionally rig a temp fix on something for a customer until I can get the part in for a proper fix. Every once in a while the rigged fix is better/stronger than the original and I'll leave it that way, but only with the knowledge of the customer.Dan______________Airco Heliwelder IVIdealarc 250/250 AC/DC tombstone
Reply:It might help if we could see pics of all the controls on the front. It sounds to me like it might have a pulse feature and you've got it turned on.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Irish,I've been out of town the last week. I'll try to get a pic of all the controls but I don't see anything like pulse control. There are only a couple of controls I didn't get a pic of and I was pretty certain of what those did at the time.Dan______________Airco Heliwelder IVIdealarc 250/250 AC/DC tombstone
Reply:Here are the additional pictures. I still haven't tried Tigging with it yet. Yesterday used stick to fix a couple things on an old brush mower for the tractor. Contactor acted up intially but then settled down. Looks like I'll have to file the contactor contacts after all. I tried using the start current with stick, it seems to control the current totally. I'd set it high to get an easy start arc on the old paint/grease encrusted metal, but it never seemed to drop the amps down the main current setting. Ended up turning it off and just using main current. Does anyone know the thread size of the gas and water input and output solenoids? I haven't tried hooking up my WNI-17 torch to the gas yet but it doesn't look like the fittings on my hoses are that large. I also have to get a short hose for going from the solenoid to my power adapter. As seen in the picture this machine has a blank panel to the left of the power switch. I've seen a picture of another of these machines that has a pulse control option in that position. Attached ImagesDan______________Airco Heliwelder IVIdealarc 250/250 AC/DC tombstone
Reply:that thing looks to be in excellent condition for the year !    for 160 bucks u cant go wrong  even if it needs a little work .>Innovations are what i leave behind for History
Reply:Looks like the contactor is the likely culprit alright. I just thought that the way you described it acting there might be pulse feature.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Took the contactor out this weekend and filed the points. Still acts like it has lost a leg of the input voltage until the amps are cranked up, then the other leg kicks in and it works fine after that. I'm thinking maybe the contacts on the range selector? Any other ideas? I can post a picture of the schematic if that would help.Dan______________Airco Heliwelder IVIdealarc 250/250 AC/DC tombstone
Reply:It could be the range selector. I had trouble with my old Hobart a few times in that area.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm