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  • hobart 10k exciter circuit

    New to me 1999 Hobart champion 10k has no output of ac voltage. I measured at the brushes and had zero. I used an external battery and flashed the field (like I have a clue, this and 1 more generator would make two that I have touched) well started it up and plugged in a drill and I had ac voltage. Not stable, was fluctuating between 80 and 115 for maybe 5 minutes, then it simmered down to 115 and held stable. I was JACKED!. I went back in the house feeling like the luckiest guy around and went out an hour later and put the cover back on it. Started it up, no ac voltage. Took the cover back off, did the flash thing again and started it. The drill ran for about 5 seconds and stopped. I did it again, and the drill ran for 5 seconds and stopped.

    So I am pretty sure the card has issues. I did disconnect the wires from the bridge and confirm the diodes are ok. The board is labeled 201027 for a part number.

    I followed wire 21 back to the board which appears to lead to whatever the devices are with the big heat sinks on them.

    I got this machine for a song and if I could get it running without a huge expense it would start my new year off right since the engine is awesome! The wiring behind the face panel looks unmolested, the hour meter works and it shows 900 hours so my guess is a shop ran it too hard.


    Any tips, schematics or repair places you can recommend would be appreciated. I can solder well, but this goo covering it is something I haven't worked with before. I presume there is some method to soak the board to dissolve that stuff or something so you can work on the devices.

    I have found similar postings on the internet for this issue but no fixes. I hope someone can suggest a regulator or triac or something to shotgun replace. I cannot read the device numbers at this time, there too hidden in the heat sinks.

    Thanks!


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    Last edited by hydroax; 01-03-2017, 05:32 AM.
    Hobart 190 mig welder 13 months old still in the box
    champion 10k welder/generator- on the to do list

  • #2
    The coating on the circuit card is called conformal coating. It comes in several different types and the removal procedure depends on what type it is. To try to identify what type Hobart uses, look at the identification procedure outlined here: http://www.circuitrework.com/guides/2-3-1.html. Polyurethane is popular for non-DOD and aerospace applications due to its ease of re-workability. Maybe one of the Hobart Experts knows and can advise via this forum.

    The heat-sinked device(s), or maybe only one of them (hard to tell) regulate the exciter current to the armature. To get 120/240 VAC at the outlets the welding current knob has to be set to maximum if I recall.

    There are two companies that come to mind that perform repair of welder PC cards. You can look up the number for the circuit card in question on those websites to see if it is listed and what the repair charge would be. If it is not listed then a phone call or e-mail would be the next step.

    http://www.yorkelectronics.com/html/brandsrepaired.html

    http://www.innovatcorp.com/

    Without having the schematic for the PC card it is very difficult to troubleshoot if it is indeed defective. Hobart evidently does not release schematic diagrams for troubleshooting purposes.

    Edit: With the welder NOT running, removing and reseating the connectors to scuff through any oxide or corrosion layers is worth a try.
    Last edited by canoecruiser; 01-02-2017, 03:31 PM.
    CanoeCruiser
    Harris dual-stage O/A
    Lincoln AC/DC buzzbox
    Hobart IronMan 210
    Lincoln PowerMig 135
    Miller 3035 spoolgun
    Thermal Arc 185
    Thermadyne Cutmaster 52
    Angle grinders, vicegrips, the usual suspects
    Two hands, tired body, not enough time...

    Comment


    • #3
      http://www.yorkelectronics.com/html/brandsrepaired.html

      http://www.innovatcorp.com/

      Thanks for the response. I sent both companies an email. Innovatcorp wanted 300 dollars to fix a board and that sounds kind of high compared to some others. I did a google and found a number of listings for repair places but my fear is sending the card off to somewhere and having the company hold it hostage for payment if I decline the repair charge.

      I was hoping to find someone on this board who has had a good experience with a company to give me a little more confidence with it.

      Like these guys http://www.acsindustrial.com/repair-pricing.php

      Send it to us, we will tell you what it will cost after we have it in our hands. Don't like our prices? Don't want to wait 15 days for that price? Ok, we will send it back to you broke. Two weeks passes..you call them up trying to find your card..."What card? Oh we sent that back last week. Let us get back with you on that tracking number. What's your name again?"

      I have found the board for sale for 600ish dollars which blows my good deal right out of the water. That's more than I paid for the unit.

      If I cannot find a solution it may be better to wire up an external excite signal since it seems to be the only circuit that is not working. Idle works, 12 volts to the clock works. I really don't want to do that, I want a 100 percent stable working welder without the bailing wire.

      I have removed and reinstalled all connectors as well as ohmed out the brushes, just to make sure. I also verified the bridge. Im afraid its in the card.


      Thanks for the suggestion I will post the results good or bad.
      Last edited by hydroax; 01-03-2017, 05:21 AM.
      Hobart 190 mig welder 13 months old still in the box
      champion 10k welder/generator- on the to do list

      Comment


      • #4
        Is the red LED coming on on the board after it runs for at least 5 seconds?

        Keith

        Comment


        • #5
          Originally posted by Hobart Expert Keith View Post
          Is the red LED coming on on the board after it runs for at least 5 seconds?

          Keith
          Nopers. Tried it twice. AC outlet not live either. Thanks!
          Hobart 190 mig welder 13 months old still in the box
          champion 10k welder/generator- on the to do list

          Comment


          • #6
            check from wire 21 on the brushes to ground(chassis) and there should always be 12-14 Vdc whenever the unit is running. If you have that then check across the brushes and you should have 15-17 Vdc when running at 3600(run) RPM.

            Keith

            Comment


            • #7
              Originally posted by Hobart Expert Keith View Post
              check from wire 21 on the brushes to ground(chassis) and there should always be 12-14 Vdc whenever the unit is running. If you have that then check across the brushes and you should have 15-17 Vdc when running at 3600(run) RPM.

              Keith
              Im at work right now but yesterday I checked across the brushes and had zero. I had the oldest son verify the led a second ago. I will verify wire 21 when I get home at 3pm. Thanks
              Last edited by hydroax; 01-03-2017, 01:30 PM.
              Hobart 190 mig welder 13 months old still in the box
              champion 10k welder/generator- on the to do list

              Comment


              • #8
                I couldn't stand it. Called home had the son measure wire 21, he said

                Read 18 at first but gradually and relatively quickly dropped to like 2 volts
                Hobart 190 mig welder 13 months old still in the box
                champion 10k welder/generator- on the to do list

                Comment


                • #9
                  Sounds like a diode on the board opening up. Check wire 20 to the board to make sure it maintains 12 volts to chassis and if so then the issue is in the board. Either bad solder joint or diode D23 opening. If not then there is a problem with the 12 supply from the engine regulator to the board.

                  Comment


                  • #10
                    Originally posted by Hobart Expert Keith View Post
                    Sounds like a diode on the board opening up. Check wire 20 to the board to make sure it maintains 12 volts to chassis and if so then the issue is in the board. Either bad solder joint or diode D23 opening. If not then there is a problem with the 12 supply from the engine regulator to the board.
                    pulled board, reflowed connections on diode d23 and wire 20 at the board. used a multimeter to check the diode d23 and it checked ok. (which as you know may or may not be breaking down with real current) With unit running I had a stable 11.35dc voltage going into d23. I was quoted 300 dollars to repair the board so a diode replacement may be a better idea or if these heat sinked devices are in the circuit maybe replace them as well. Thanks for your assistance. Paul
                    Hobart 190 mig welder 13 months old still in the box
                    champion 10k welder/generator- on the to do list

                    Comment


                    • #11
                      If you continually have 12V at 20 to chassis but not at 21 to chassis then D23 is failing or there is a bad circuit path or solder joint. If D8 or Q5 shorted the generator would put out high voltage and if the rotor shorted to ground it would either fail D23 or drop the 12 supply so low the engine would load up or even die.
                      D23 is there to prevent the higher rotor voltage on wire 21 to ground (can go as high as 230Vdc during normal operation) from getting back into the charging system on the engine.

                      Keith

                      Comment


                      • #12
                        Originally posted by Hobart Expert Keith View Post
                        If you continually have 12V at 20 to chassis but not at 21 to chassis then D23 is failing or there is a bad circuit path or solder joint. If D8 or Q5 shorted the generator would put out high voltage and if the rotor shorted to ground it would either fail D23 or drop the 12 supply so low the engine would load up or even die.
                        D23 is there to prevent the higher rotor voltage on wire 21 to ground (can go as high as 230Vdc during normal operation) from getting back into the charging system on the engine.

                        Keith
                        can you tell me the part number or spec on d23 and suggest a chemical to clear this conformal coating? I cannot read it without removing it. I will try to locate a replacement locally.
                        Last edited by hydroax; 01-04-2017, 08:35 AM.
                        Hobart 190 mig welder 13 months old still in the box
                        champion 10k welder/generator- on the to do list

                        Comment


                        • #13
                          D23 3a 1000v axial leads *1n5408

                          Comment


                          • #14
                            Originally posted by Hobart Expert Keith View Post
                            D23 3a 1000v axial leads *1n5408
                            sweet thanks!
                            Hobart 190 mig welder 13 months old still in the box
                            champion 10k welder/generator- on the to do list

                            Comment


                            • #15
                              Originally posted by hydroax View Post
                              can you tell me the part number or spec on d23 and suggest a chemical to clear this conformal coating? I cannot read it without removing it. I will try to locate a replacement locally.
                              This will most likely remove the conformal coat: https://www.zoro.com/techspray-confo...g&gclsrc=aw.ds

                              It is also available from Allied Electronics for a few dollars more: http://www.alliedelec.com/techspray-...FcZKDQodtJ8F7w

                              This diode is a drop-in replacement and is rated for 6 amps; the reverse voltage rating is the same at 1000 volts: http://www.alliedelec.com/nte-electr...FY5WDQodQKsNTg. Any silicon diode with equivalent or better ratings to what Keith referenced will work fine.

                              Before removing the existing diode, note which way it is oriented by identifying the cathode (should have a band around one end of the body). It sounds like you have experience with electronics so you should be in good shape.
                              CanoeCruiser
                              Harris dual-stage O/A
                              Lincoln AC/DC buzzbox
                              Hobart IronMan 210
                              Lincoln PowerMig 135
                              Miller 3035 spoolgun
                              Thermal Arc 185
                              Thermadyne Cutmaster 52
                              Angle grinders, vicegrips, the usual suspects
                              Two hands, tired body, not enough time...

                              Comment

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