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Hobart Handler 135

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  • Hobart Handler 135

    I am trying to fix the control circuit card on my handler 135 and need some help. Can anyone tell me the part number of the transistor with the hear sink attached to it? It appears to be some type of voltage regulator but it has no number on it. Something on the board gets hot after about a minute of run time and I have changed the two relays the large 50 ohm resistor and the 12 volt drive motor but have had no success yet.
    Thanks in advance
    midget

  • #2
    Your header might have "Attention Hobart Repair". They are very good about getting back to you.
    "Good Enough Never Is"

    Comment


    • #3
      My Hobart Dealer is not that helpful. He is into doing the work not giving advice. That is the reason I posted on this site. I hope that some other Hobart Rep will read it and tell me what I need to know. From what I read on this and other forums the Hobart/Miller Handler 135 control board is a known problem and should have been corrected thru a recall. I have used one spool of aluminum and one spool of regular wire in this thing since I bought it. IT SHOULD NOT HAVE THIS PROBLEM.
      Thanks anyway
      midget

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      • #4
        ...which is why I suggested a post heading to catch their attention...
        "Good Enough Never Is"

        Comment


        • #5
          Originally posted by midget9999 View Post
          I am trying to fix the control circuit card on my handler 135 and need some help. Can anyone tell me the part number of the transistor with the hear sink attached to it? It appears to be some type of voltage regulator but it has no number on it. Something on the board gets hot after about a minute of run time and I have changed the two relays the large 50 ohm resistor and the 12 volt drive motor but have had no success yet.
          Thanks in advance
          midget
          Does the welder operate correctly?

          You mention that something on the board gets hot after a minute of run time. That's the large 22W resistor at the top of the board. It functions as a bleed resistor for the output capacitor of the machine. It will get hot, that's why the resistor is sized as large as it is. At maximum open circuit voltage, you'll get approximately 15W from that resistor. That's the heat that you feel.

          The transistor mounted on the heat sink in the middle of the board is a 2N6388 NPN Darlington transistor and serves as the motor drive transistor. If that part needs to be replaced, it can be obtained from www.digi-key.com. The usual symptom of a bad motor-drive transistor is the motor running full speed no matter where the WFS control is set (shorted device), or a slow motor (one transistor of the Darlington pair bad) or motor not running at all (open device).

          When you depress the gun trigger, do the board relays close and open when you release the trigger?

          Please provide a little more information.

          Thanks,

          Darrell

          Comment


          • #6
            Darrell,

            Thanks for the reply. I am having lots of trouble getting technical info on this circuit board.

            I have replaced both relays with the exact part number. (NT90RHC-S 24CB)

            I replaced the large resistor (50 OHM 25 watt)

            I replaced the small wire feed motor (RS540SH)

            I am now going for the transistors. If that don't work I am out of ideas.

            Yes the welder still works after the feed motor stops. I ruined a tip when the feed motor stopped and I didn't stop soon enough. The feed motor will cool and then it will run again for about 15 seconds. It will run for almost a minute when it sits overnight. Nothing is hot to the touch except the 25 watt resistor and I feel that is normal.

            I hope this is enough info if not ask more questions.
            Again thanks for the response
            Midget

            Comment


            • #7
              Originally posted by midget9999 View Post
              Darrell,

              Thanks for the reply. I am having lots of trouble getting technical info on this circuit board.

              I have replaced both relays with the exact part number. (NT90RHC-S 24CB)

              I replaced the large resistor (50 OHM 25 watt)

              I replaced the small wire feed motor (RS540SH)

              I am now going for the transistors. If that don't work I am out of ideas.

              Yes the welder still works after the feed motor stops. I ruined a tip when the feed motor stopped and I didn't stop soon enough. The feed motor will cool and then it will run again for about 15 seconds. It will run for almost a minute when it sits overnight. Nothing is hot to the touch except the 25 watt resistor and I feel that is normal.

              I hope this is enough info if not ask more questions.
              Again thanks for the response
              Midget
              That's good feedback. With that information, I don't think that you have a transistor problem. With the problem as described, it looks like the motor protection device, PTC1, may be the likely suspect. This device is located in the middle of your board. It's a flat, yellow disc-shaped device.

              To perform a quick test to verify that this is the problem prior to ordering parts and replacing the device, the easiest method is to simply place a jumper across the device. you may need to scrape the conformal coating from the leads near where they're soldered into the board to make good contact with your jumpers. If PTC1 is the problem, the motor will function normally with the device shorted out.

              PTC1 is an over-current protection device, basically a self-resetting fuse.

              Here's the spec sheet:

              http://littelfuse.com/data/en/Data_S...elfuse_60R.pdf

              Here's the digi-key link:

              http://search.digikey.com/scripts/Dk...&name=F2013-ND

              You'll want the 60R185 device.

              If this device isn't available, just find a substitute with a rating that's similar such as:

              http://search.digikey.com/scripts/Dk...ame=F2871CT-ND


              Darrell

              Comment


              • #8
                PTC1 device

                Darrell,
                I put a jumper across the PTC1 wafer and the units runs without cutting out: However, I have no control over the motor speed. Is this normal or do I need to change the 2N6388 transistor to restore speed control? Man I really appreciate your help.
                Midget

                Comment


                • #9
                  Originally posted by midget9999 View Post
                  Darrell,
                  I put a jumper across the PTC1 wafer and the units runs without cutting out: However, I have no control over the motor speed. Is this normal or do I need to change the 2N6388 transistor to restore speed control? Man I really appreciate your help.
                  Midget
                  Yes, you will need to replace the transistor. You can get that from Digi-key as well, just search for a 2N6388 NPN transistor. It's pretty low-cost.

                  You may not need to replace the PTC, it may be cutting out because the transistor is shorted, which is what it's supposed to do. But, since the PTC doesn't cost much either, it may be wise to replace both just to save time. Your time is worth more than the part cost.

                  Darrell

                  Comment


                  • #10
                    Darrell,
                    I am ordering both parts now. Shipping cost more than the parts. I can not express my appreciation enough. I have been trying to get this kind of help for over two months. This is a great web site and I will pass it on.
                    Thanks Again.
                    Earl Pitts alis midget
                    Last edited by midget9999; 01-15-2009, 08:57 AM.

                    Comment


                    • #11
                      Thanks for the information it was the same problem with my handler135 had to buy a few extra parts but it was well worth it my dealer wasnt much help 35.00 dollars and one hour and it is as good as new but then its only had one and a half rolls of wire thru it once agian thanks alot

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                      • #12
                        I don't have a Hobart welder but with service as good as this I'll give a good hard look the next time the opportunity arises. I am impressed!

                        Comment


                        • #13
                          hobart 135 motor not turning

                          hey darell.. i have a hobart 135 my drive motor dosnt work.. heres what ive tested and done

                          tested.. power switch=works
                          reset fuse on back=works
                          gun trigger=works
                          tested motor with 12 volts = works goes fast
                          relay=works

                          tested votage from the posative and negative leads on the motor at 5 volts no morot turn..

                          replaced q1 and ptc1 with right parts from digikey.. now i get 12 volts.. still motor dosent turn..

                          50 ohm resister r1 shows 42 ohms... i assume thats right? i havent replaced that or the 220 uf 50 volt capacator so those are the only other 2 things i could replace...

                          it just seems if im getting 12 volts the motor should turn right? and ideas?

                          also i tested the variable resister for the wire feed.. i get 54.00 k ohms from 0 and i even ran it to 100 it jumps from 8.0 k ohms on around.. so thats working right?


                          im lost before i got 5 volts now i got 12 volts but motor isnt working still.. obviously i have good ground.. but no amps behind it.. i got this welder free the guy said it smoke. once.. so posiibly the r1 resistor and the cap i should replace? any help woul be apreciated

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                          • #14
                            Originally posted by locutus_1 View Post
                            hey darell.. i have a hobart 135 my drive motor dosnt work.. heres what ive tested and done

                            tested.. power switch=works
                            reset fuse on back=works
                            gun trigger=works
                            tested motor with 12 volts = works goes fast
                            relay=works

                            tested votage from the posative and negative leads on the motor at 5 volts no morot turn..

                            replaced q1 and ptc1 with right parts from digikey.. now i get 12 volts.. still motor dosent turn..

                            50 ohm resister r1 shows 42 ohms... i assume thats right? i havent replaced that or the 220 uf 50 volt capacator so those are the only other 2 things i could replace...

                            it just seems if im getting 12 volts the motor should turn right? and ideas?

                            also i tested the variable resister for the wire feed.. i get 54.00 k ohms from 0 and i even ran it to 100 it jumps from 8.0 k ohms on around.. so thats working right?


                            im lost before i got 5 volts now i got 12 volts but motor isnt working still.. obviously i have good ground.. but no amps behind it.. i got this welder free the guy said it smoke. once.. so posiibly the r1 resistor and the cap i should replace? any help woul be apreciated
                            It may help to call our tecnical support team at 800-332-3281.

                            The one variable that I don't see listed in your check list is the control power to the p.c. board. This power is supplied by a winding on the fan motor. If the board isn't getting power, the relay that closes the motor circuit won't energize to allow the motor to run. Of course, without power, the motor drive transistor Q1 won't be switching anyway.

                            When you mentioned that the previous owner claimed a failure that let the smoke out, this made me think of this component.

                            Call the tech support guys and they can walk you through a couple checks on the fan motor.

                            Darrell

                            Comment


                            • #15
                              ok the fan motor on the back works, and i have 12 volts at the wire feed motor.. so i belive i dont have the amps behind it .. you can have voltage but not amps.. and in the motor schmatic it lists the components all of them work... for the motor..

                              so what your saying is the 2 leads off the fan run the power to the pc board?

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