301g question

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Hey everyone!New here. I'm actually a commercial HVAC tech. My hubby is a machinist/welder and recently bought a used Miller Trailblazer 301G, and is planning on operating a mobile welding business. When he bought it, the PC1 board literally had a hole blown through it. He bought a new one, and i replaced it. I went through all the connections, replaced what was corroded or loose, checked fuses. He fired up the motor, no problem. Had 120 and 240v out of the receptacles. He tried to weld with it, and it blew RU2 on the PC1 board. Any ideas? Bear with me, like I said, I'm an HVAC tech, not a welder tech...Thanks!!!!!Dana
Reply:Hi Dana, If you don't get an answer that fixes the problem try the Miller forum, there are a few individuals who are good at this type of machine problemsRichardWest coast of Florida
Reply:Welcome to the forum Dana.If you were to search the Trailblazer threads here you would find that a significant number of units have experienced either a PC1, PC2 or both failure.  Most of these failures were the result of jumping a dead battery while attempting to start the unit rather than removing the battery to charge it.  In the case of dual board failures, a failure on one causes the failure of the other.  If undetected, this can cause a repeat failure such as you've experienced.That being said, the PC2 Control Board is a 3-level "sandwiched" circuit unit that I know of only one person to ever have successfully repair and as he put it was a significant challenge at that.  As such, PC2 is typically classified as non-repairable by those companies that do board repairs and I suspect you may find one or more component failures on PC2 that has resulted in your repeat failure of Power Board PC1.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110

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