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I got a couple of welders from a friend who has a construction business and was buying new gear in exchange for firewood. One works, but the 250g (serial #JK691415 750 hrs) starts and runs fine but won't weld and the plugs don't have any power. I took the hood off and if I take a pair of jumper cables and touch them to the field capacitor the AC outlets (and presumably the welder) start to work. I don't have a service manual but was wondering if anyone had any ideas what might be wrong based on this behavior. I don't need two welders and would probably sell the 250g if I can get it working. Any thoughts?
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If you have the exciter board in yours & it is bad this is how you bypass it. (I did this on mine) You can call Miller direct & ask for the engine drive dept. They will help you troubleshoot it. Note that your serial # is just after these.
O/k so here is my notes. For serial # JG018501 thru JJ355008. Circuit diagram SA-112 555. Remove sheet metal to get at upper most board (exciter feild shutdown board PC3) with red light. All you have to do to bypass board is disconnect wire #20, this is "E" on the schematic & wire #29, this is "H" on the schematic. Connect them together & it's done. You can carefully get the connectors out of the plug as I did.
If you have power now then check your open circuit voltage which should not go higher than about 92 volts with machine set to max & revved up to welding speed. Mine went to 91.
If OCV is high do a visual on the varister(spelling) (this is also called a suppresssor) which is located on the rectifier. If it looks burned then replace. I have a note here with part # 046819 which is $18 at miller4less.com.