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Plasma Cutter Giant Tools LGK-60 not working

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    #21
    Re: Plasma Cutter Giant Tools LGK-60 not working

    sorry no idea .. i have a neighbour that fixes them but cant use them so he pays me to to do the work with the machines . . thinking about it there must be high voltages needed and be driven by certain frequencies ,

    Comment


      #22
      Re: Plasma Cutter Giant Tools LGK-60 not working

      What is the part number of IC 1 in the photo that you have posted

      Do it have any optic sensor on any of the boards and have you checked them


      Have you checked if the IGBT module is getting the command power signal to turn on
      9 PC LCD Monitor
      6 LCD Flat Screen TV
      30 Desk Top Switching Power Supply
      10 Battery Charger Switching Power Supply for Power Tool
      6 18v Lithium Battery Power Boards for Tool Battery Packs
      1 XBox 360 Switching Power Supply and M Board
      25 Servo Drives 220/460 3 Phase
      6 De-soldering Station Switching Power Supply 1 Power Supply
      1 Dell Mother Board
      15 Computer Power Supply
      1 HP Printer Supply & Control Board * lighting finished it *


      These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

      1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
      2 Hem Saw Computer Stack Board

      All of these had CAPs POOF
      All of the mosfet that are taken out by bad caps

      Comment


        #23
        Re: Plasma Cutter Giant Tools LGK-60 not working

        Originally posted by petehall347 View Post
        sorry no idea .. i have a neighbour that fixes them but cant use them so he pays me to to do the work with the machines . . thinking about it there must be high voltages needed and be driven by certain frequencies ,
        Umm, no... the other way around. AC is converted to DC, then the DC is converted back to low voltage, high current AC. PWM is good to 500khz so I am guessing they run around 250khz.

        Originally posted by sam_sam_sam View Post
        What is the part number of IC 1 in the photo that you have posted

        Do it have any optic sensor on any of the boards and have you checked them


        Have you checked if the IGBT module is getting the command power signal to turn on
        That is the control module or where everything is starting to happen. There is a small PSU, IC1 is a UC3843 PWM, then there is this massive gate driving circuit. I am thinking in order for the arc board to turn on, the inverter has to be running as well. I've checked what I could on this controller board, but didn't find anything that sticks out.
        On top of the inverter board to the far right are 2 connectors. The smaller one with the 2 red cables coming out go to the arc board and gets switched by the black relay. From there it goes through the transformer and through bunch of arc circuitry, that spark gap and the 2 output lugs XS1 and 2.

        I still haven't figured out how this controller board gets enabled or turned on.
        Attached Files
        Last edited by CapLeaker; 04-12-2018, 07:30 AM.

        Comment


          #24
          Re: Plasma Cutter Giant Tools LGK-60 not working

          Originally posted by CapLeaker View Post
          Umm, no... the other way around. AC is converted to DC, then the DC is converted back to low voltage, high current AC. PWM is good to 500khz so I am guessing they run around 250khz.

          Originally posted by CapLeaker View Post
          [LIST]
          That is the control module or where everything is starting to happen. There is a small PSU, IC1 is a UC3843 PWM,
          Do you think IC1 is working I seen this type of chip go bad in servo controller before if this chip does not cost much I would recommend replacing it

          Originally posted by CapLeaker View Post

          then there is this massive gate driving circuit. I am thinking in order for the arc board to turn on, the inverter has to be running as well. I've checked what I could on this controller board, but didn't find anything that sticks out.
          On top of the inverter board to the far right are 2 connectors. The smaller one with the 2 red cables coming out go to the arc board and gets switched by the black relay. From there it goes through the transformer and through bunch of arc circuitry, that spark gap and the 2 output lugs XS1 and 2.

          I still haven't figured out how this controller board gets enabled or turned on.
          What is the part number for the IC chip that has a ( #6 ) on it
          I thinking that this chip might be controlling the power on command if it is some type of micro controller

          Can you show this part of the circuit ( arc circuitry ) board if you can

          Also some do you get any type of arc at all when you push the button to weld
          Last edited by sam_sam_sam; 04-12-2018, 03:22 PM.
          9 PC LCD Monitor
          6 LCD Flat Screen TV
          30 Desk Top Switching Power Supply
          10 Battery Charger Switching Power Supply for Power Tool
          6 18v Lithium Battery Power Boards for Tool Battery Packs
          1 XBox 360 Switching Power Supply and M Board
          25 Servo Drives 220/460 3 Phase
          6 De-soldering Station Switching Power Supply 1 Power Supply
          1 Dell Mother Board
          15 Computer Power Supply
          1 HP Printer Supply & Control Board * lighting finished it *


          These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

          1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
          2 Hem Saw Computer Stack Board

          All of these had CAPs POOF
          All of the mosfet that are taken out by bad caps

          Comment


            #25
            Re: Plasma Cutter Giant Tools LGK-60 not working

            On the last pic that 16pin IC (I think it is a KA3525A For some reason it also could be 9535 or a 8535, hard to tell) is the PWM that drives a couple of predrivers (them 4 TO-220 packages). While there aren't any shorts, them two gate drivers measure a bit different on the 16pin IC (compared from one to the other).

            There is absolutely no arc at all, if I press the button, all that happens is I get air.

            Comment


              #26
              Re: Plasma Cutter Giant Tools LGK-60 not working

              is there a sensor that checks air pressure before arc can happen ? just a thought like .

              Comment


                #27
                Re: Plasma Cutter Giant Tools LGK-60 not working

                Originally posted by petehall347 View Post
                is there a sensor that checks air pressure before arc can happen ? just a thought like .
                This one doesn't have that feature. It only has the air valve. There are also no extra little gimmicks in the wand that disables the machine, if the head is off or something like that.

                Comment


                  #28
                  Re: Plasma Cutter Giant Tools LGK-60 not working

                  Originally posted by CapLeaker View Post
                  On the last pic that 16pin IC (I think it is a KA3525A For some reason it also could be 9535 or a 8535, hard to tell) is the PWM that drives a couple of predrivers (them 4 TO-220 packages). While there aren't any shorts, them two gate drivers measure a bit different on the 16pin IC (compared from one to the other).

                  There is absolutely no arc at all, if I press the button, all that happens is I get air.
                  I would replace the PWM IC chip and see what happens did you check the ( 4 TO-220 devices to see they all the same exact reading
                  9 PC LCD Monitor
                  6 LCD Flat Screen TV
                  30 Desk Top Switching Power Supply
                  10 Battery Charger Switching Power Supply for Power Tool
                  6 18v Lithium Battery Power Boards for Tool Battery Packs
                  1 XBox 360 Switching Power Supply and M Board
                  25 Servo Drives 220/460 3 Phase
                  6 De-soldering Station Switching Power Supply 1 Power Supply
                  1 Dell Mother Board
                  15 Computer Power Supply
                  1 HP Printer Supply & Control Board * lighting finished it *


                  These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                  1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                  2 Hem Saw Computer Stack Board

                  All of these had CAPs POOF
                  All of the mosfet that are taken out by bad caps

                  Comment


                    #29
                    Re: Plasma Cutter Giant Tools LGK-60 not working

                    Well, I did put that thing back together and did more measurements. I have 345V DC going to the inverter board, so the PSU is O.K, but nothing coming out from the inverter when keyed up.
                    However there is just one plug that goes from the control board to the inverter board and the wires are red, black, green and green. If I unplug the control board from the inverter board, I measure a short of 8 ohms between the red and black wire at the inverter side.
                    The control board side measures 680 Ohms between red and black.
                    On the picture them red and black wires go to that little transformer underneath those 4 wires. O.k. maybe there should be AC on it and I got nothing.
                    Left of that little transformer there are 4 black and 4 red wires. Those come from the PSU and provide the 345VDC. That red side is going to BOTH lugs of that little transformer on the left side If I measure between that, I get 2 ohms resistance.
                    The black and red wire from the 4 pin port go to the right side of the transformer. That is where the 8 Ohms short comes from.
                    If I measure DC between either black and red to either of the green wires, I get 25.8VDC untriggered and 25.3VDC when I trigger that wand. I am pretty sure the inverter isn't getting keyed up. No output of the inverter, there wont be any sparks.
                    I've tried every AC / DC measurement combination available on the red, black, green, green wire to see if there is a some clear signal that triggers the inverter on and didn't find any. Bummer.
                    Attached Files

                    Comment


                      #30
                      Re: Plasma Cutter Giant Tools LGK-60 not working

                      I am going to order replacements for all 3 IC's, on the control board and see whats happening...
                      The two green wires go to the PWM pre drivers, the black is GND and the red one goes also to that little vertical pcb on the control board.

                      Comment


                        #31
                        Re: Plasma Cutter Giant Tools LGK-60 not working

                        Well guys and gals... The plasma cutter is FIXED! The last problem was that the control board didn't get the signal to turn on.

                        Besides the bad main filter capacitors, the trouble was actually on the arc board. The turn on signal was there for the air valve, but not for the controller board to turn on the inverter. I chased things around on the arc board and found 2 bad 22k resistors R6 and R15. R6 was way out and R15 was out of spec. Changed them out (look at the brown resistors) put it back together and I got 465V AC from the inverter, but no arc. Adjusted the spark gap FDQ to roughly 1.25 to 1.50mm and low and behold I've got the arc going in between them plates. Finally that case is closed and that stupid thing isn't smarter me.

                        This fix is for those that have the air valve go, but no AC voltage coming out of the inverter board when keyed. So there will be absolutely no spark from the wand, acts like dead.

                        On the arc board the trigger goes to CN5 (blue and green wire). The turn on signal for the controller board is on CN4 (the one on the right to CN5) and has a red, blue, green wire.
                        Between that blue and green wire should be 5V DC going to the controller board when triggered.
                        Attached Files
                        Last edited by CapLeaker; 05-08-2018, 12:08 PM.

                        Comment


                          #32
                          Re: Plasma Cutter Giant Tools LGK-60 not working

                          Good work

                          I am glad you finally figured out why it was not working

                          Save it from the land fill
                          9 PC LCD Monitor
                          6 LCD Flat Screen TV
                          30 Desk Top Switching Power Supply
                          10 Battery Charger Switching Power Supply for Power Tool
                          6 18v Lithium Battery Power Boards for Tool Battery Packs
                          1 XBox 360 Switching Power Supply and M Board
                          25 Servo Drives 220/460 3 Phase
                          6 De-soldering Station Switching Power Supply 1 Power Supply
                          1 Dell Mother Board
                          15 Computer Power Supply
                          1 HP Printer Supply & Control Board * lighting finished it *


                          These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                          1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                          2 Hem Saw Computer Stack Board

                          All of these had CAPs POOF
                          All of the mosfet that are taken out by bad caps

                          Comment


                            #33
                            Re: Plasma Cutter Giant Tools LGK-60 not working

                            yeah... had to wait for things to warm up around here. I didn't like working in the cold garage. Actually, once one figures a plasma cutter out how things work inside, it isn't that bad. Of course a schematic would have been helpful, but that's waaay to easy, hi.

                            Comment


                              #34
                              Re: Plasma Cutter Giant Tools LGK-60 not working

                              Originally posted by CapLeaker View Post
                              Actually, once one figures a plasma cutter out how things work inside, it isn't that bad.
                              This is half the battle is understanding how it works and how the controls work

                              Originally posted by CapLeaker View Post
                              Of course a schematic would have been helpful, but that's waaay to easy, hi.
                              It would be easier

                              but most of the time there are no schematic
                              or
                              they are not complete only certain part
                              or
                              they are function block diagrams
                              Last edited by sam_sam_sam; 05-15-2018, 06:16 PM.
                              9 PC LCD Monitor
                              6 LCD Flat Screen TV
                              30 Desk Top Switching Power Supply
                              10 Battery Charger Switching Power Supply for Power Tool
                              6 18v Lithium Battery Power Boards for Tool Battery Packs
                              1 XBox 360 Switching Power Supply and M Board
                              25 Servo Drives 220/460 3 Phase
                              6 De-soldering Station Switching Power Supply 1 Power Supply
                              1 Dell Mother Board
                              15 Computer Power Supply
                              1 HP Printer Supply & Control Board * lighting finished it *


                              These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                              1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                              2 Hem Saw Computer Stack Board

                              All of these had CAPs POOF
                              All of the mosfet that are taken out by bad caps

                              Comment


                                #35
                                Re: Plasma Cutter Giant Tools LGK-60 not working

                                BTW, I've heard back from that guy today. He was saying that this plasma cutter never worked so good like it does now. Made my evening!

                                Comment


                                  #36
                                  Re: Plasma Cutter Giant Tools LGK-60 not working

                                  Yes sir

                                  that is what is important

                                  I like that kind of feedback
                                  9 PC LCD Monitor
                                  6 LCD Flat Screen TV
                                  30 Desk Top Switching Power Supply
                                  10 Battery Charger Switching Power Supply for Power Tool
                                  6 18v Lithium Battery Power Boards for Tool Battery Packs
                                  1 XBox 360 Switching Power Supply and M Board
                                  25 Servo Drives 220/460 3 Phase
                                  6 De-soldering Station Switching Power Supply 1 Power Supply
                                  1 Dell Mother Board
                                  15 Computer Power Supply
                                  1 HP Printer Supply & Control Board * lighting finished it *


                                  These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                                  1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                                  2 Hem Saw Computer Stack Board

                                  All of these had CAPs POOF
                                  All of the mosfet that are taken out by bad caps

                                  Comment


                                    #37
                                    Re: Plasma Cutter Giant Tools LGK-60 not working

                                    Read with great interest your posts on this. I too have the same unit same problem, though the caps don't looked cooked like yours. My question you mentioned that the cutter was hooked up wrong, wondering what was meant by than, my unite is a 220V set-up. Thanks

                                    Comment


                                      #38
                                      Re: Plasma Cutter Giant Tools LGK-60 not working

                                      Someone had put a different plug on the cable and was wired up wrong.

                                      Comment


                                        #39
                                        Re: Plasma Cutter Giant Tools LGK-60 not working

                                        Originally posted by CapLeaker View Post
                                        Someone had put a different plug on the cable and was wired up wrong.
                                        What the power in cable if so why was it marked to the way it suppose to be hook up

                                        If not the main power in

                                        What cable was hooked up wrong
                                        Last edited by sam_sam_sam; 03-20-2020, 09:56 PM.
                                        9 PC LCD Monitor
                                        6 LCD Flat Screen TV
                                        30 Desk Top Switching Power Supply
                                        10 Battery Charger Switching Power Supply for Power Tool
                                        6 18v Lithium Battery Power Boards for Tool Battery Packs
                                        1 XBox 360 Switching Power Supply and M Board
                                        25 Servo Drives 220/460 3 Phase
                                        6 De-soldering Station Switching Power Supply 1 Power Supply
                                        1 Dell Mother Board
                                        15 Computer Power Supply
                                        1 HP Printer Supply & Control Board * lighting finished it *


                                        These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                                        1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                                        2 Hem Saw Computer Stack Board

                                        All of these had CAPs POOF
                                        All of the mosfet that are taken out by bad caps

                                        Comment


                                          #40
                                          Re: Plasma Cutter Giant Tools LGK-60 not working

                                          The story I've got told was that someone had cut the plug of the power cord and put a different plug on it, randomly hooking up the 3 wires. However, this was corrected but the unit didn't work anymore and came to me. Surely there was a different plug on the cord.

                                          Comment

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