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  • wire feed not working

    just bought this welder (millermatic 135) , wire feed motor not working . I put a new potentiometer dial on it , still not working . feed motor turns freely . I noticed a red light on the circuit board came on when I pushed the trigger on the gun .does that mean the board is BAD ??? Is there a way to check the pc board ? Any body run into this , and is there anything else I should check . Thank You

  • #2
    Welcome, Stinson. Afraid I can't be much help with the welder-diagram is just a big blank block for the circuit card, and I don't have a 135 to look at. But I'm sure interested in your screen name--a true classic! One of the smoothest things in the sky!

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    • #3
      Originally posted by stinson108 View Post
      just bought this welder (millermatic 135) , wire feed motor not working . I put a new potentiometer dial on it , still not working . feed motor turns freely . I noticed a red light on the circuit board came on when I pushed the trigger on the gun .does that mean the board is BAD ??? Is there a way to check the pc board ? Any body run into this , and is there anything else I should check . Thank You

      My Net Flix movie isn't holding much of my interest, but your question has my short term attention. Post a serial number. Don't think however that means I know something, I don't, but I'm sure it'll help someone who does know something with a better chance of answering?

      If I was a guy who pretended to know something...I might asked, you say the drive is not working but the motor turns freely? Tell me you did something to discover this out? And since I have you on the line, you got no speed or some speed?

      Now for advice...I don't think your going to find a magic internet cure. But if you start searching the forum for past topic posts of such troubles, internet for videos, what you discover is some pretty solid tips for testing and checking. Just curious, did you disassemble the drive gear box clean and lube it up? Add a drop of oil to each end of the motor? Confirmed liner isn't kinked or filled with friction slowing gunk? Does the fan work?

      Good luck, it's not an uncommon problem. But if I was to guess, you can narrow it down to three things. two of which could be parts on the board, or the "Board". The other...I'd only be guessing and what you need is to test stuff.

      Pictures were from the inside of a Hobart 135. Like I mentioned, no magic internet cure found, a bunch of reading, a few video's, just a little cleaning, a little maintaining, and some testing.
      Your welcome.

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      • #4
        AERONCA41.... Just so happens I got my sport pilots license in a aeronca champ (1947) . And getting my private license in the Stinson. Love taildraggers !!!!

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        • #5
          Noel ... I will post the serial number when I get home .
          I did take the motor apart and clean and lubed everything .
          Thank you I will research some more and test .

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          • #6
            Most likely it's the PC board. Don't take the motor apart. Get a meter, disconnect the wires to the motor and check for 12 VDC across the wires. If it isn't there it's your board. Make sure your heat setting isn't in between #'s. Board failure is mostly cause by drive rollers cranked down too tight on these small machines. I've seen 1 motor failure to 100 board failures.

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            • #7
              Looks like there are at least 2 different part numbers for that board. You'll have to check your machine's serial number, get the proper manual from the SUPPORT link above if you don't already have one, find the part number of the board, and then call Miller for an updated part number since the ones in the manual are no longer available. Looks like 207463 or 207466 in a random serial number manual I looked at. 207466 has been replaced by 226321; not sure about the other one. Looks like $250-$300 bucks or so. Talk with Miller at 920-734-9821. Check at Miller4less.com for pricing once you get a good part number. Miller does not provide schematics to fix the board except to their authorized service folks.

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              • #8
                Noel... the serial number is LC489437 .
                1997CST... I checked the wires and I'm getting 15 volts . I'm assumming that's alright . I connected a 9 volt battery on the drive motor and it turned the motor over .

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                • #9
                  When I started in this racket, they were still gas welding air craft fuselages. The home built crowd still does, or at least those that haven't been sold on GTAW as being god's gift to welding everything. I have plans for a 3/4 scale SE5A bi plane. Just saying, you guys who fly...we on the ground hold some envy to you. Not enough life probably but I have the plans.

                  Stinson 108, I'm not the gifted one on fixing welders. I gave up what worked for me, and admittedly still have questions that have no answers that I fully understand.

                  Now this board failure stuff. My ol man would say, leave the thinking for the horses, they got bigger heads. Well it's easy to say, replace the board. That's the world we live in. The TV...Oven doesn't work, Dish washer, Microwave, Laundry machine, Fridge...welder?

                  What I want is something more then that for explanation. What I'm finding is the information that's out there, while available, you have to dig for it to find it, need and have a willingness to learn and digest it, and it comes in small pieces that then have to be applied to understand how it works and is applied to operate and function.

                  I didn't loose welding characteristics, I lost low end speed control and drive motor torque.

                  Maybe I didn't diagnosis it well? But it worked for me. Would replacing a board put a crispness back in it's step? Maybe? But because I didn't go that route I discovered a degree of resistance in the drive. Hmm?
                  I have a buddy who repairs watches and clocks...friction keeps poor time.

                  With that working again, it lead me to thinking I have something else electronic on the way out? That something is weakening in function and the only way to know for sure is to understand how it functions and plays a role in making things work?

                  What I'm slowly learning is how electronic switching devices work and function. How electronic filters work, resisters, capacitors...all those things on a wiring diagram. How to test them. And then the board to is understandable.
                  Not high on my list really, but I retain stuff. Small scraps of paper, the pile is building up.


                  -1997CST Board failure is mostly cause by drive rollers cranked down too tight on these small machines. I've seen 1 motor failure to 100 board failures. "

                  I have to ask, please tell how that cranked down pressure causes that to occur? And if you have seen 100 board failures, is that where it stopped? I'm thinking your holding out the orange but not giving it a hard enough squeeze?







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                  • #10
                    1997CST's statement makes a lot of sense. When you crank down the pressure, it makes the motor have to work harder to turn the rollers. The motor can hack it, apparently, but the amplifiers are not designed to continually deliver that much extra drive current, and get hot. Heat is the enemy of virtually everything electronic; in the stint I spent as a Reliability Engineer, we were always about cooling things better. Keep most parts cool enough, and they will last almost forever. Get 'em hot, and they don't like it. Current above design parameters = increased heat = decreased life. I have (thankfully!) forgotten the formulas many years ago, which is probably just as well.

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                    • #11
                      Stinson, if I understand your message right, you are getting voltage (15 VDC) to the motor leads when you pull the trigger? Is this when the motor is still connected? Also, where are you checking the voltage?

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                      • #12
                        Also, if you're looking for a cheaper alternative than buying a new board, there is a company called Innovat Corporation in Virginia that can repair your board for about $140 plus shipping based on their price listing. I am sure there are other companies that do this too, but I found this company when reading through an old thread on either here or welding web. They're sending me a replacement board for my XMT, which would have been way more trouble than it was worth to me to fix myself.

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                        • #13
                          Originally posted by Aeronca41 View Post
                          1997CST's statement makes a lot of sense. When you crank down the pressure, it makes the motor have to work harder to turn the rollers. The motor can hack it, apparently, but the amplifiers are not designed to continually deliver that much extra drive current, and get hot. Heat is the enemy of virtually everything electronic; in the stint I spent as a Reliability Engineer, we were always about cooling things better. Keep most parts cool enough, and they will last almost forever. Get 'em hot, and they don't like it. Current above design parameters = increased heat = decreased life. I have (thankfully!) forgotten the formulas many years ago, which is probably just as well.

                          There we go, a magic word, amplifiers. I do get some of this, just not much. I know enough that some where in the DC side of things the signal is weakening? Gates not opening and closing or something isn't amplified as high or long maybe?

                          Cranking down on the drive rolls is like starting a cars engine with thick cold oil. So what's happening, and why? Battery not producing cranking amperage?

                          I added the pictures for effect, nothing more. They could mean something or nothing at all?
                          In my mind, I see a picture to explain it, I'm not sure if I'm understanding it however? I over came drive roll resistance and it was back working, but I know something is off on the snap crackle crispness. For give the simplicity, but it appears to me, the spring hold the gates closed are weakening?

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                          • #14
                            Noel, The conceptual drawing below might help understanding--I can't say this is how Miller did it or not since their drawings are proprietary, but the concept has to work something like this. Once you have set the wire speed control, when you pull the trigger on the gun, the motor drive circuits turn on and start the motor. (The motor and it's drive circuits may work on either AC or DC--you can design either). Motor RPM is sensed and fed back to the comparator as a voltage (or frequency) directly proportional to motor speed; where it is checked against the desired RPM which is determined by the wire speed setting. The comparator will tell the control circuit to deliver more or less drive power as required to achieve a balance between the two comparator inputs. Now, if you crank down the pressure on the drive rolls (or hold them back with a gloved hand, for that matter), RPM will drop because of the increased load and the comparator will call for more power, so the driver circuits begin to work harder -- and run hotter, reducing their life expectancy. Thus, the experience of welder techs that you see far more bad circuit cards than you do motors. The motor is apparently the more robust part of the design, and the weakest fails first.
                            Last edited by Aeronca41; 02-19-2019, 08:48 AM.

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                            • #15
                              The only thing I can add is my frame of reference when troubleshooting a MM 211 Autoset and working through an S-22P12 wire feeder that I received for an understandably good price (it would only feed at full speed, regardless of the trigger pull). Hopefully the next eplanation doesn't confuse too much but follows aeronica's block chart with what I saw on the two machines' PCBs. Pretty much the way those two feeders worked is a single MOSFET (big three legged chip on the heatsink in the upper left PCB of the MM211, on the right in the S22) PWM motor driver with current feedback. The negative lead of the motor connects in series with a shunt (two white cement resistors in the upper left corner of the MM211 PCB, one resistor in the lower right of S-22 PCB), to ground. The positive lead connects to the mosfet (I think it is the center leg of the Mosfet), with the mosfet gate lead connected to controller (network or transistors, capacitors, and resistors between), the other Mosfet lead connects to whatever the positive voltage rail is (there is a big electrolytic capacitor connected between here and ground to help keep the motor running at the right speed). The controller chip senses the voltage across the shunt, which it compares to the reference voltage from the wire feed dial (through a buffer and filter networks of operational amplifiers, resistors, and capacitors to protect the controller as well as provide the right compensation to keep the controller's time response as fast as safely possible) and determines how long to turn on the MOSFET for each pulse. The MM211 uses a microcontroller for the control chip, the S22 uses a specific chip designed for motor control. The only reason for mentioning this is because that network of transistors, capacitors, and resistors between the dial and controller and MOSFET is very different between the two. There is also a protection diode (two legged component, may be on a heatsink) across the Mosfet leads the protects the Mosfet from voltage spikes when it turns off the motor.

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