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Millermatic 35s needs your help

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  • Millermatic 35s needs your help

    Hi All
    I need help from someone that knows how to fix welders. I have a Millermatic 35S that I bought new in 1976. It has been very well maintained and in very nice shape. I installed a Tweco Mini Mig 160 years ago. This 38 yr old machine will still put down a nice looking bead of weld but it does have an issue. It doesn’t seem to want to weld in lower settings and you have to crank it up in a higher range to weld than I feel you should need. Also it doesn’t want to start to weld. When you first pull the trigger it acts like you have the setting to low with a humped up cold looking weld then after a few or more seconds it will weld like no tomorrow and lay down this kick ass weld for as long as you want. If you jump and start another bead she goes like ****. But if you lay down the gun for awhile it will spit and sputter until it starts going again. You can actually hear when it starts to change to a nice weld.
    I’ve been doing searches about these welders on the web and I have come across forums that talk about the 6 capacitors going bad and I think from what I’m reading may be my problem. I have removed the caps and do not see any that appear to have any physical damage. The 6 caps are marked 9000uf 35v and are 2’’ dia and 4 ½ lg. Now the same 35s welders that were produced in later years Miller changed the caps to 20000uf 35V. I have seen guys that have replaced there old 9000 uf caps with the higher number 20000 uf with no problems (I guess). Now my question is I found 6 Mallory caps for sale for $85 but they are 22000MFD 50VDC will these be too much?
    I know nothing about this stuff I originally tried to get my welder fixed but everyone tells me its old just by a new one. I was offered a new welder for $800 then another for $400. So now I will try to fix it myself. I will put $1000 dollars in a old $400 welder before I will buy their China garbage.
    Can anyone out there help me……Thanks Jake

  • #2
    First try pulling the cover and cleaning the contacts on the voltage selector switch. The remove and clean all the wire connections on the switch. Then remove and clean the spots where it connects to the machine.


    • #3
      I'm one of those that had to replace the (6) 9000uF caps with 20000uF units in my '81 MM200 when one of the originals blew. I stepped up to 50V versions and wouldn't hesitate to use the 22000uF you've found. from your description I would be surprised if this didn't fix your problem but would certainly recommend you go thru the steps that walker outlined as well which is just good PM if not the cause.
      MM200 w/spot controller and Spoolmatic 1
      Syncrowave 180 SD
      Bobcat 225G Plus LPG/NG w/14-pin*
      *Homemade Suitcase Wire Feeder
      *WC-1S & Spoolmatic 1
      PakMaster 100XL
      Marquette "Star Jet" 21-110


      • #4
        I replaced all of my caps=Welds like a new welder, Thank to Duane's advice. I also used the higher rated Mallory caps.