Need help with first welder

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I just purchased a used P&H 300amp ac/dc tig machine. I tested it out today and found that the foot control will start an arc and release gas but does not change the amperage. This machine appears to be from the 1960's and parts are no longer made for it. I cleaned the contacts inside the control, but it did not fix the problem. How do I test the foot control to see if the problem is in the foot control its self or actually inside the welder?I don't think it will work, but can I use a foot control from another welder or must it be specific to this machine. I think Linde had a similar model.I don't want to but if it is going to be hard to fix I may try to return it to the guy I bought it from. He bought it at an auction.
Reply:If you bought it from an individual and not a shop or used store that give warranties, the general rule is once you buy it, its yours, unless the guy gave you some kind of guarantee, I would doubt he would give you your money back for it!thats why its called buyer beware!As to your problem with it, someone with experience with those will have to answer that, I have never used a Tig.#1. If you don't like what I wrote, or if it offends you, then don't read it!#2. I am living life the way I see fit, if you don't like the way I'M living, tough sh**!
Reply:This may sound dumb, but on my Dialarc HF, probly of similar vintage as your P&H, there two seperate switches on the front panel that decide what the foot pedal is allowed to control.  One switch is for contactor, the other is for current.  Both of these have to be in the 'remote' position for the foot pedal to both start the arc and vary the current for tig welding.  Maybe your machine has more than one switch also?MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Also, I forgot to say that on my Dialarc, the control cable for the foot pedal has 2 seperate plugs that connect it to the machine.  One is a 2-pole plug for the contactor and the other is a 3-pole plug for the current.  Might want to check your machine's connections.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Ken - The seller guaranteed it to work, he had just purchased it and did not use it.Desert - Thanks for the help. But I do not think that is the problem. There is one switch for remote control which I had on. There are two plugs a 3 pole for the contactor and a four prong for the output. The 3 pole plug and wire seem to work because the control does turn on and off. What do you ride in the desert? I have a couple ktms.I called the guy I bought it from and he said if the amp control works on the machine he thinks he can fix the foot control. I the machine seems to work great as a power supply I welded some 1/8" 7018 with good results. So I’m hoping to get this foot control straightened out so I can get practicing.
Reply:Glad the previous owner is willing to help, that's always cool.  Sounds like you'll  get it working.I ride 85 Honda ATC250R and 89 Honda CR500R.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:I think I have the same machine but the next size larger.  Mine is green and says A.O. Smith but made by P&G.  Huge machine and welds like a dream on DC.  I have tried to TIG al. with it but have not had much luck.  I think the gap on the high frequency needs set.    I like hearing all the relays slapping around when changing settings.  I am pretty sure you have to set the amp control on the face to the highest setting you want and that is all the higher the foot control will put out.  You also have to set the toggle switches to remote for current control and contactor control.  Dan
Reply:Originally Posted by DanD78I think I have the same machine but the next size larger.  Mine is green and says A.O. Smith but made by P&G.  Huge machine and welds like a dream on DC.  I have tried to TIG al. with it but have not had much luck.  I think the gap on the high frequency needs set.    I like hearing all the relays slapping around when changing settings.  I am pretty sure you have to set the amp control on the face to the highest setting you want and that is all the higher the foot control will put out.  You also have to set the toggle switches to remote for current control and contactor control.  Dan
Reply:As long as everything else works on that machine, the pedal isn't anything more than a rheostat "a resistor for regulating a current by means of variable resistances" , if its bad, shouldn't be too hard to fix.#1. If you don't like what I wrote, or if it offends you, then don't read it!#2. I am living life the way I see fit, if you don't like the way I'M living, tough sh**!
Reply:The output wire which comes out of the foot control has a 4 prong plug. If I buy a more modern miller hand or foot control with 4 pins can I put the old plug on it and use the new control on my old machine?
Reply:Yes, you can change plugs, just have to get the wires connected to the right poles on the plug.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op