retrofitting spool gun to original passport?

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Hey guys,Has anyone looked into the feasibility of retrofitting an original miller passport to be able to weld aluminum?I suppose the first step would be to find out if it produces DC or AC output.Next step would be determining which if any spool guns could be fitted to it.
Reply:hmm, a quick test with a multimeter shows ~42 volts DC and about 9 volts AC.  I suppose the AC component is for starting the arc.  Bummer.
Reply:passport owner's manual also seems to indicate this unit is only capable of DC.I suppose one could rig up an H-bridge of IGBT's to switch polarity around constantly and make AC, but:1) 4 IGBT's would cost several hundred dollars.2) you would get square wave AC -- I think most welders make a sin wave.  that might be bad.3) designing such a circuit would get me half way to building my own TIG unit.
Reply:GMAW aluminum is a DC process, same as GMAW steel.As for AC GTAW, squarewave machines have many advantages over sinewave machines.
Reply:Originally Posted by MAC702GMAW aluminum is a DC process, same as GMAW steel.As for AC GTAW, squarewave machines have many advantages over sinewave machines.
Reply:It was covered on Miller....by the time you get all the parts to do it with you will have a non warrantied passport that will have cost you the same as getting a new passport +
Reply:Agree with 84ZMike.   I researched this extensively and I'm still using my Passport in original form to weld steel and looking for a good deal on a WC115A controller with contactor to use my XR/Spoolmatic spool gun on the Bobcat.The 'upgrade' to change a Passport to a Passport + for use with a Spoolmate 100 for welding aluminum involves changing both the main circuit board and the motor control board, as well as the front panel and associated wiring between the boards and the plug for the gun.   It can be done, but the cost is prohibitively high and not worth it, in my opinion.  Some modifications and upgrades I have done have been worth it and worked well, despite the nay-sayers, but this one didn't pan out.  Win some, lose some.  Last edited by DesertRider33; 05-02-2008 at 01:41 PM.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op