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Troubleshooting Trailblazer Pro 350D low welder output

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  • Troubleshooting Trailblazer Pro 350D low welder output

    Hi, my first post here. I'm troubleshooting this welding in our shop that recently had one of its brushes replaced which look like it melted but the collector rings are intact. The search engine came back with nothing The generator side is working find however, the welder side have very little output to burn metal. The open voltage at the outputs are just below the max. The brush voltage between 131 and 132 is 134 volts AC when in AC mode and 57 volts DC when in DC mode which don't seem right to me but may not be the case. We are on an island in Alaska and the nearest service center is hundreds of miles away. Any suggestions? I do believe both boards and the big capacitor has been replaced

  • #2
    To add to the discussion, I haven't meggered the windings yet but in my bag of tricks if I need to. Given the low hours on it, I'm pretty sure it will pass. Just checking the proverbial gas tank before rebuilding the engine sort of speak

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    • #3
      Lets get a few things from you. Low hours? How many? You say OCV is close to right? What is the OCV. I wouldn't worry about winding. 99.9% chance they are ok.
      Check weld connections.
      Reset circuit breaker(s) CB5 and CB6 (see Section 7-9). Check for faulty remote device connected to RC4. Check control settings. Place V/A Adjust switch S3 in Panel position, or move switch to Remote position and connect remote control to Remote receptacle RC4 (see Sections 4-11 and 5-1). Place Process/Contactor switch in an Electrode Hot position, or place switch in a Remote position and connect remote contactor to Remote receptacle RC4 (see Sections 4-11 and 5-1). Check leads and connections at DC Polarity/AC switch S1. Clean slip rings, and install new brushes if necessary (see Section 9-11). Disconnect leads 131 and 132 from brushes, and check continuity across slip rings. Replace rotor if necessary. Check main rectifier SR1, and replace if necessary. Check current transducer LEM, and replace if necessary. Disconnect stator weld excitation leads 91 and 92, and check continuity between leads. Replace stator if necessary. Check for open or shorted winding in weld stator, and replace if necessary. Check stabilizer DC-Z for signs of winding failure. Check continuity across windings, and check for proper connections. Replace DC-Z if necessary. Check power/regulator board PC1 and connections, and replace if necessary (see Section 9-5). LED5 and LED6 on PC1 light when PC1 is energized. Check control board PC2 and connections, and replace if necessary (see Section 9-7). LED3 on PC2 lights when PC2 is energized

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      • #4
        Thank you for the response. The welder has only 42.9 hours on it. OCV is open circuit voltage, voltage output under no load listed on page 9 of the owner's manual. Brushes continuity is good. Settings on welder, good. Swamp them around and still have good power on generator side and no change on the welder side. all the breakers Will start checking the other items. Both circuit board 1 and 7 were replace. Ohm'd out the rings. I have continuity but at 33 Ohms. all circuit breakers are good and have 23VAC at the remote plug between terminal A-G and 116 VAC between I-G. No remote controller. Voltage output from the welder windings are 50 Volts between 12-14, 14-15, and 16-12. I'm not sure what the specs are for SR1 but the prelim readings between the diodes and Caps are consistent between the 6 sets within

        I am currently suspecting that circuit board 2 is toast since although I can strike an arc but just enough to melt the rod. I can crank the adjustment knob to max and it does not have any affect on it.

        thoughts?
        Last edited by sparkyinak; 06-04-2019, 07:21 PM.

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        • #5
          I checked everything out. Long story short, all checked out good, except:
          LEM CT input voltage is like 29 VDC the default Voltage for the standard model is only 15VDC, not to say this particular model operate at a higher voltage. I have a call into the LEM factory. If in fact this particular CT is rated at only 15 VDC, it gets is power from the Circuit Board #2 which I suspect already.


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          • #6
            All Miller LEM's operate with a +/_ 15VDC. If you unplug the LEM does your output go wide open?

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            • #7
              LEM responded. Yes they CT’s operate on 15 Volts but with a bipolar power supply so they need a 30volt with a center ground. I’ll be testing it CT later for a signal but based on that, I’ll be surprised that the CT is bad

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              • #8
                If you have CC/DC OCV: Stick mode: +62.5 volts DC (idle RPM), +76.3 volts DC (weld/powerRPM) at output terminals then try new weld leads.

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                • #9
                  LEM tested out good and the leads were tested on another welder and worked fine. the same low output from the welder is the same no matter at what current setting and mode (electrode positive, negative, AC) so it really leaves nothing else but PCB 2

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