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1979 MM200 Millermatic 200 Fan Motor Repair

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  • 1979 MM200 Millermatic 200 Fan Motor Repair

    So my MM200 Mig stopped working after just a few tack welds the other day. When I pulled the gun trigger no action whatsoever. After turning down the shop radio and other loud devices, I noticed that the fan was not on. I opened the manual and took a quick look at the schematic. Found that F1 is the fuse for 115VAC leg that the fan motor uses. F1 is located on the face of the welder. Installed a new fuse and the fan started to spin up, but very slowly and labored. The fuse then expired and further investigation was required. I pulled the tins off and noticed a small trace of smoke coming out of the fan motor.
    I went to the manual again to find the replacement PN (081-373)
    However I found no current availability reference to this PN. So I decided to remove the old one and spec something close enough that would work.
    Upon removal of the fan motor I found that it was a Dayton motor PN 3M548
    A quick google search found that the PN was still valid and was offered by many sellers. ($55-$75)

    Hope this helps others looking to keep 40+ yr old welders up and running.


    Last edited by jeepgif; 01-03-2019, 05:11 AM.

  • #2
    That is a nice looking MM200! Thanks for the info; should help some folks along the way.


    • #3
      Good work.


      • #4
        Nice, I know there a lot of mm200 fans (pun intended) out there