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Trailblazer 250G restoration project... no power

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  • Trailblazer 250G restoration project... no power

    Hello everyone. I picked up a Miller Trailblazer 250G as a fixer upper.
    Serial # JG138621 Hours = 1800

    Seller said he bought it several years ago and the welder/power wasn't working. He never got around to working on it and when I got it, the motor wouldn't crank.

    Anyway, motor is now running great. New gas and new voltage regulator is all it needed. Engine idles nicely and when the switch is flipped, it revs to full power. I'm making no progress with the welder/generator. I'm getting no power with the welder or AC outlets.

    Here's where I'm at:
    Flip on power switch and the panel LED lights, and the exciter board (I think that's what it is) LED lights up. It looks to be a new board compared to the other boards. The outer coating of the large capacitor on this board looks like it has melted a little. After cranking, both LED's go out.

    Brushes look good; polished slip rings, resistance between slip rings looks good. Resistance between slip rings and ground = OL

    Main capacitor looks new. Ohms test shows ohms slowly rising up to about 4 M

    The one fuse on the panel looks good and all breakers are good. The other fuse is an inline fuse on a red wire which is disconnected. That loose wire, along with 2 loose black wires are on the left of the machine near the rectifiers.

    AC voltage across the 2 black wires is .5 V at idle, and approx 2 V at full RPM. I'm assuming these 2 wires go to the SCR bridge since the 2 AC terminals on it have nothing attached.

    It looks like 2 rectifiers below the SCR bridge. One of those has a terminal with nothing attached. I'm assuming the red wire w/ fuse attaches here. The red wire has no DC voltage on it.

    One of these rectifiers has a loose wire leaving it and heads toward the bundle of wires coming from the generator. It ends with a male plug. Coming out of that bundle of wires from the generator, is 2 loose wires. One has a male plug, one has female plug.

    The only manual I could find and reference is for models beginning w/ KA which are models with the AC option. Mine is DC only. I've attached a few pics of the back of the panel where the wires are loose.

    Any help would be appreciated.

    Thanks!
    Attached Files

  • #2
    All those wires have numbers on them making it pretty easy to tell where they went by simply looking a an owners manual or the machines wiring diagram which should be on the inside of one of the covers.

    Comment


    • #3
      **** cruizer, you're a freaking genius! Who would have thought to look at the back of the panel! < slapping self on head >

      I've been looking at the only manual I've found online for the TB 250G and I knew it wasn't close.

      Any chance you might have manuals for this old of a machine?

      Thanks again!
      Last edited by firefight; 05-03-2012, 09:34 PM.

      Comment


      • #4
        Look above, under the "resources" tab. Entering your serial number, I get a manual dated October 1986, effective with serial number JG018501.

        http://www.millerwelds.com/om/o426_mil.pdf
        Obviously, I'm just a hack-artist, you shouldn't be listening to anything I say .....

        Comment


        • #5
          I had a problem with mine losing power. Working one minute then nothing. It was the exciter board & I was able to bypass it with millers help. Been working fine ever since. The exciter board was only used a couple years then they did away with it. I have the instructions on how to bypass it written down somewhere. If your interested let me know & I'll find them.

          You can also call Miller engine drives as they will help you troubleshoot it.
          MM250
          Trailblazer 250g
          22a feeder
          Lincoln ac/dc 225
          Victor O/A
          MM200 black face
          Whitney 30 ton hydraulic punch
          Lown 1/8x 36" power roller
          Arco roto-phase model M
          Vectrax 7x12 band saw
          Miller spectrum 875
          30a spoolgun w/wc-24
          Syncrowave 250
          RCCS-14

          Comment


          • #6
            Originally posted by JSFAB View Post
            Look above, under the "resources" tab. Entering your serial number, I get a manual dated October 1986, effective with serial number JG018501.

            http://www.millerwelds.com/om/o426_mil.pdf
            Now I'm really feeling like a moron. I called myself checking the resources, that's where I got the WRONG manual from.

            Thanks, that helps alot.

            Comment


            • #7
              Originally posted by MMW View Post
              I had a problem with mine losing power. Working one minute then nothing. It was the exciter board & I was able to bypass it with millers help. Been working fine ever since. The exciter board was only used a couple years then they did away with it. I have the instructions on how to bypass it written down somewhere. If your interested let me know & I'll find them.

              You can also call Miller engine drives as they will help you troubleshoot it.
              If you could find them that would be great!

              I have all the wiring back where it belongs. Still no power and the LED on the exciter board remains lit. The manual says when the LED is lit, the excitation field is shutdown.

              Am I correct in assuming, that until the exciter field is restored, no other trouble shooting can take place?

              Thanks again for all the help guys!

              Comment


              • #8
                Originally posted by firefight View Post
                If you could find them that would be great!

                I have all the wiring back where it belongs. Still no power and the LED on the exciter board remains lit. The manual says when the LED is lit, the excitation field is shutdown.

                Am I correct in assuming, that until the exciter field is restored, no other trouble shooting can take place?

                Thanks again for all the help guys!
                did you ever try to plug a drill into the electrical socket and turn it in reverse by hand to re-excite the generator?

                Comment


                • #9
                  Originally posted by tommy2069 View Post
                  did you ever try to plug a drill into the electrical socket and turn it in reverse by hand to re-excite the generator?
                  I tried the drill trick with no luck. I'm not sure if that isolates the problem to any one area or just means that trick doesn't work.

                  I'm not sure where to go from here.

                  All help and suggestions are appreciated!

                  Comment


                  • #10
                    O/k so here is my notes. For serial # JG018501 thru JJ355008. Circuit diagram SA-112 555. Remove sheet metal to get at upper most board (exciter feild shutdown board PC3) with red light. All you have to do to bypass board is disconnect wire #20, this is "E" on the schematic & wire #29, this is "H" on the schematic. Connect them together & it's done. You can carefully get the connectors out of the plug as I did.

                    If you have power now then check your open circuit voltage which should not go higher than about 92 volts with machine set to max & revved up to welding speed. Mine went to 91.

                    If OCV is high do a visual on the varister(spelling) (this is also called a suppresssor) which is located on the rectifier. If it looks burned then replace. I have a note here with part # 046819 which is $18 at miller4less.com. I checked now & this is a good #.
                    Last edited by MMW; 05-05-2012, 05:22 AM. Reason: verified part #
                    MM250
                    Trailblazer 250g
                    22a feeder
                    Lincoln ac/dc 225
                    Victor O/A
                    MM200 black face
                    Whitney 30 ton hydraulic punch
                    Lown 1/8x 36" power roller
                    Arco roto-phase model M
                    Vectrax 7x12 band saw
                    Miller spectrum 875
                    30a spoolgun w/wc-24
                    Syncrowave 250
                    RCCS-14

                    Comment


                    • #11
                      Thanks MMW! Disconnected the 2 wires from the board and connected them together. Cranked her up and she started smoking a little from the generator. Didn't really smell electrical or like plastic.

                      On a side note, the very first time I got the engine cranked it started smoking like that also. After a cool down and restart, it never did it again

                      I shut it down and it continued to smoke for a few seconds, rats nest or leaves maybe? Anyway, gave it a chance to cool and cranked her back up. No smoke this time. .

                      Selector on 75-250 A, voltage across SMAW terminals was 82V.
                      Selector on 25-80 A, voltage was 125V.

                      No AC power at receptacles. Breakers were okay. I flipped the contactor switch on and then back off (for no apparent reason). Still no power so I shut it down.

                      Grabbed welding leads, hooked them up, started motor and NOTHING. No voltage across terminals at any setting. Took welding leads off and tried again, no voltage! F1 and F2 were okay.

                      If the contactor were to stick in the on position, would it prevent voltage at terminals?

                      One step forward, two steps back. Any ideas?

                      Thanks for all the help!

                      Comment


                      • #12
                        Any time the factory smoke gets out it's not a good thing.

                        The by-pass procedure shared by MMW simply turns a unit into a pre SN JG111773 machine by eliminating the PC3 Exciter Field Board from the control picture.

                        Call Miller Customer Service Engine Drives and request a copy of the Technical Manual for your unit (give them the SN). It sounds like a shorted rotor (or stator) and the technical manual will walk you thru all the checks for both.

                        Keep in mind the previous owner stated it didn't have any weld/auxiliary power output so you just inherited the original cause that you now have to figure out.

                        Get the Technical Manual and it will eliminate 99% of the guess work.
                        Last edited by duaneb55; 05-12-2012, 09:42 PM.
                        MM200 w/spot controller and Spoolmatic 1
                        Syncrowave 180 SD
                        Bobcat 225G Plus LPG/NG w/14-pin*
                        *Homemade Suitcase Wire Feeder
                        *HF-251D-1
                        *WC-1S & Spoolmatic 1
                        PakMaster 100XL
                        Marquette "Star Jet" 21-110

                        Comment


                        • #13
                          Thanks Duane. I'll call them Monday morning. I only see one customer service number on their site, so I guess that's the one.

                          You're right about inheriting the problem, that's why I bought it for basically the cost of the cables. I love dumpster diving

                          Comment


                          • #14
                            When I called Miller I asked for "engine drive tech support". They were awesome & walked me through it.
                            MM250
                            Trailblazer 250g
                            22a feeder
                            Lincoln ac/dc 225
                            Victor O/A
                            MM200 black face
                            Whitney 30 ton hydraulic punch
                            Lown 1/8x 36" power roller
                            Arco roto-phase model M
                            Vectrax 7x12 band saw
                            Miller spectrum 875
                            30a spoolgun w/wc-24
                            Syncrowave 250
                            RCCS-14

                            Comment

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