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Miller Trailblazer 250g woes

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  • Miller Trailblazer 250g woes

    Hey everyone! First, thank you to everyone that has posted in the forum. I have learned a lot from you all. I have searched heavily and found a lot of things to check for my issue.

    Ok, first the machine is a Miller Trailblazer 250g, serial number KC201679. I downloaded the owners manual, and it has been handy. I asked Miller for the tech manual, to no avail.

    Now, the problem I have, which I know you all have heard before, is that I got a welder for really cheap, but it does not weld or generate power. Well, very little power, [email protected] 120v plug, and [email protected] 220v plug. The voltage does fluctuate up and down depending on engine rpms.

    I have checked F1, F2, SR2, SR3, slip ring resistance center to outer and to ground, C1, all circuit breakers, and all resistors. I cleaned and checked resistance of all connections also. There is no exciter board on this machine.

    The last suspect is the PC2 Field Current Regulator Board. I checked all connections and visually looked it over, and didn’t see any glaring issues.

    I do know the idle control board has let the magic smoke out, but even manually revving the motor I only get about double the AC power at the outlets.

    Now, I’d love to buy the PC2 board, but I haven’t had any luck locating one. I do have a few vendors that will repair the board, but it’s pricey. That’s not a big deal because I got the machine for a song, but I just want to get a few(or even just a 2nd) opinion whether I’m on the right track.

    please let me know if I accidentally left out some pertinent info. Also, if anyone knows where I can purchase the tech manual, I would love some direction. I see one on eBay for ridiculous money($56) that I would likely pay, if it were for the correct serial number.

    Also, if anyone knows a procedure to check the Field Current Board, I’d be indebted.

    Thanks in advance!

  • #2
    One thing I noticed, that I’m not sure about, is the wiring diagram shows the wires connected to the brushes in the opposite order, from the main revolving field, than they actually are. You can see in the pic, I annotated what the actual wiring is on the machine. I don’t want to swap them around and test because I don’t want to cook an SCR if the diagram is wrong. If anyone with a trailblazer wouldn’t mind looking at theirs, that would put my mind at ease.

    thanks, Steve


    • #3
      19 is your positive wire and that has to be located on the middle slip ring. I'm looking at a tech manual and I cannot find which wire (17 or 18) is suppose to be closest to the armature or bearing. Normally there is a notation. I would start by putting 19 in the middle. I don't think you can do any damage if 17 and 18 are reversed. Length of wire might help you. But for sure it will not weld with out 19 in the middle. Finding someone on here with this machine probably slim.


      • #4
        I totally does have 19 in the middle, and 17 and 18 are correct also. Guess I’m going cross eyed messing with this thing. I decided to send the PC2 board to MRO for repair. Fingers crossed it works.