3phase Thunderbolt

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I posted this below but have another question so I thought I'd post here. I'm looking at an older Miller Thunderbolt ac/dc at a good price.  I don't have the serial number yet. The owner tells me it requires 3 phase power. It has a black face with the amp handle on top. That's about all I know at this point. I looked through the owners manuals at Miller's site and at two miller catalogs I have. Neither place list a 3 phase thunderbolt. Both say it will run on up to 460volts depending on how you wire it. I'm not really questioning the owner but I'm confused and hoping he may be also. If it is 3phase can it be converted to single phase? I know it would help if I had the serial number. Thanks for any help.
Reply:Sounds like you have found the same Thunderbolt I have. Mine is 220V. If you end up snagging the machine I could take the cover off and take some pics of the hook ups inside so's you could duplicate it. My serial number ended up tracing back to being a 1993 model year when I looked it up on Millers site.  I recall that I had to run several numbers off the machine to find the right one. I printed the owners manual off the internet as mine didn't come with one. That would be an option for you also as that it shows how everything goes together inside.              If you did end up taking the machine back to 220v I would go ahead and get a few more feet of cord to play with. I have used my machine quite a bit and it's very good welder after I took the cover off and followed the periodic maint recommended in the owners manual. That crank on top can be stiff but a little grease in the right spots works just right to bring it back up to speed.
Reply:I did some checking and was told that the primary and secondary coils would have to be replaced and their cost would far outweigh the value of the welder. A few other parts would also need replacing. It's a shame because it's what I'm looking for and it was within 90 miles of me. But I'll keep looking.
Reply:I made my last post confusing by forgetting to add that it turned out to be a single phase which would run only on 460v.
Reply:Actually, whether it's a 225A or 300A model only the primary coil has to be changed. If a 225A the new 220v primary coil PN is 112 498, if 300A the new 220v primary coil PN is 097 958.Do you have or can you obtain the unit SN?MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!