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Miller bobcat not welding

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  • Miller bobcat not welding

    So I was online most of this weekend trying to find answers to why my miller bobcat 250 would not weld but the outlets worked. So read the manual and troubleshot according to its recommendations. Checked fuse 1 and 2, checked the rectifiers, the capacitor and diodes. After searching the miller forum and not coming up with anything new I decided to dive all in and start reverse diagnosing the system. I ended up finding that due to being outside, the rotator switch assemblies and the fine amp adjustment had all built up such a heavy layer of oxidation that caused too much resistance in the system. After removing them, disassembling the parts and cleaning everything with electrical cleaner and a wire brush and reinstalling everything, my welding functions came back! So if you are having this issue and all your parts check out and there is nothing burnt or broken then try cleaning all the copper contact points and testing it. I guess it makes sense, because copper left out and exposed to moisture and temperature fluctuations causes oxidation/corrosion and if the welder has not been used for a while and dials not been turned frequently they will have a lot of built up resistance on the contact points. Just hoping someone can learn from my troubles and not chase their tail like I have.

  • #2
    Great post. Thanks.