Announcement

Collapse
No announcement yet.

Miller 302 trailblazer won't go into stick-hot mode

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Miller 302 trailblazer won't go into stick-hot mode

    I have a Trailblazer 302 I bought, had a broken crankshaft when I got it so replaced the engine
    For a long time it had no weld output whatsoever, so it sat, then my buddy had his identical unit apart so I gave him my power board to test, it worked perfectly
    Last week I bought a Syncrowave 250DX, and thought, what the heck, lets plug in the TIG torch and see what happens.. It works just fine when the pedal turns it on, but I don't seem to have any heat control via the pedal, and it's still not idling down.. So it seems there's something goofy in the control board (Assembly 229660A)
    I've taken an ohm meter to the selector switch in all positions and it's working correctly

    Anyone have any ideas?

  • #2
    Broke a crank huh? Since you had it apart did you OHM out the rotor? This machines (fixed now) had a harmonic balance that at a fixed weld temperature the crank and rotor would osculate at freq and snap the crank and rub the rotor. The rotor reads 3.2 and 30.2. That's where I'd start.

    Comment


    • #3
      Originally posted by 1997CST View Post
      Broke a crank huh? Since you had it apart did you OHM out the rotor? This machines (fixed now) had a harmonic balance that at a fixed weld temperature the crank and rotor would osculate at freq and snap the crank and rub the rotor. The rotor reads 3.2 and 30.2. That's where I'd start.
      dang, I didn't get notified of a reply... I did ohm the rotor and that was fine, I really haven't fiddled with it much in the last year.. built a rolling cart for it so I could move it around, it's sitting in a barn now.. one of my "I"ll get to it projects"

      Comment


      • #4
        If you have a remote plugged in, then the 302 will run at weld speed and not idle. If you were to download a manual for the machine it would tell you this. Diagnosing would require knowing the position of the rest of the switches. Usually a pic of the front panel with everything connected and operating is a good start.

        Comment


        • #5
          Originally posted by walker View Post
          If you have a remote plugged in, then the 302 will run at weld speed and not idle. If you were to download a manual for the machine it would tell you this. Diagnosing would require knowing the position of the rest of the switches. Usually a pic of the front panel with everything connected and operating is a good start.
          I've downloaded the user and technical manuals for it.. it never goes down to idle, in any switch position, and last I tested, it stopped welding with the remote as well, trying every possible switch combination

          Is there any component level schematic for the control board? I've ohm tested the process selector switch, that's working correctly, so there must be something else wrong with it

          Comment


          • #6
            Have your S/N handy, as well as a multi meter. Pull the tin off, then call Miller Tech support. They really are a good bunch down there and will talk you through a diagnosis.

            Comment


            • #7
              I don't have the serial number handy, but I probably will do that when I get to messing with it again... I do remember having a voltmeter on the output and I was getting 1V, shorted leads there gave me 1 amp.
              If I knew what wire was the weld exciter command from the control board to the power board that would help a lot, I have oscilloscopes, voltmeters, etc.. to me it's sounding like a bad output transistor on the control board
              There's also a programming port on the control board that may have some diagnostic serial data I'll try and tap into..

              Thanks, I figured out my notifications now and I'll keep you posted when I get to it again

              Comment


              • #8
                Originally posted by Rx7man View Post
                I have a Trailblazer 302 I bought, had a broken crankshaft when I got it so replaced the engine
                For a long time it had no weld output whatsoever, so it sat, then my buddy had his identical unit apart so I gave him my power board to test, it worked perfectly
                Last week I bought a Syncrowave 250DX, and thought, what the heck, lets plug in the TIG torch and see what happens.. It works just fine when the pedal turns it on, but I don't seem to have any heat control via the pedal, and it's still not idling down.. So it seems there's something goofy in the control board (Assembly 229660A)
                I've taken an ohm meter to the selector switch in all positions and it's working correctly

                Anyone have any ideas?
                Ideas about why the Trailblazer won't idle, or why you have no output control on the Syncrowave via pedal? Those sound like two independent problems of one another.

                Trailblazer:

                verify throttle solenoid is not stuck or binding, try to actuate throttle with jumpers while its disconnected from harness to verify if component works when voltage is applied, if it does, go upstream. (throttle module, likely a pull to idle)

                Syncrowave, verify that you have output control switch set from panel to remote, and know that the pot on the syncrowave sets the maximum amperage window for pedal. check pedal potentiometer (o-10k ohms most of the time, it will say ohms on pot itself), then you start getting into current feedback and the LEM which is discontinued... I actually have 7 of those lems though LOL.

                Comment


                • #9
                  I've tried every combination of control switch setting and checked the continuity of the switch as well as the control pot, pedal works fine on my Syncrowave unit, so that's working properly as well
                  As I've said, I gave the power board to a friend, he tried it in his welder and it worked fine, so that part is good.. that pretty much leaves the control board... To me it sounds like a transistor that sends the main field command to the power board is toast... I wish I could find a schematic for the board.

                  I'm not terribly concerned about the idle-down at this point, I can fight with that later!

                  Comment


                  • #10
                    I've aquired an oscilloscope since I last worked on it so I'll check the control waveform between the control board and power board. Click image for larger version

Name:	Capture.JPG
Views:	136
Size:	44.5 KB
ID:	612718

                    Comment

                    Working...
                    X