big 20 pronblems

[M J Mauer]

Welcome to the forum.

[cruizer]

hello everyone. first time on one of these forums. i have a question for all of you. i have a miller big 20. its a 1979 welder. it runs good but no aux power and no arc at the stinger. it worked fine before lunch. i turned it off . came back after and it wouldnt arc out. i tested the aux power and there was nothing there. i did notice that the arc was gradually getting hotter over the past few months and that the governor the odd time wouldnt kick in when i struck an arc. i tested the alternator on high idle and it puts out a 120 volts. conections all look good. so i am stumped. any ideas.

Unsure why few post the serial#, there are 2 types of the big 20, 1 with 2 alternators, and one without the rear one. Zero idea where your testing either and both would have a low DC output, so where your getting 120 is beyond me

[ironman 777]

hello everyone. first time on one of these forums. i have a question for all of you. i have a miller big 20. its a 1979 welder. it runs good but no aux power and no arc at the stinger. it worked fine before lunch. i turned it off . came back after and it wouldnt arc out. i tested the aux power and there was nothing there. i did notice that the arc was gradually getting hotter over the past few months and that the governor the odd time wouldnt kick in when i struck an arc. i tested the alternator on high idle and it puts out a 120 volts. conections all look good. so i am stumped. any ideas.