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Syncrowave 250 finger tip control

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  • Syncrowave 250 finger tip control

    I've got a late 90's Sycrowave 250 that I bought new and have been using for years. Way back when it was a couple of years old I bought a finger tip control/contactor for it .... used it for a while and then the main board burned out. What would burn out was the amperage control, would still work in an on/off fashion. So ... replaced the board ($500 shortly out of warranty), back to welding .... a few months later, board burns out in the same fashion. Back to the shop ... another $500 ... when the second "new" board came in ... it was already burned out when the dealer got it, exact same components (you could see them on the board). Dealer felt bad, ordered another board, let me keep my burned out unit and gave me a complete schematic/component list for the board. Anyway .... brought the new board home, installed it, removed the finger tip control and it's been working close to 20 years.

    So ... now I have some work to do where it would really come in handy to use that finger tip control ... but I'm scared to death to hook it up for fear of burning out the board again (probably $1000 now). I have no proof it was the finger tip control that caused it. I had the control cable taped to the power cable, thought maybe it was picking up some charge from the power cable and burning out the board ... since it was the amp control circuit that was getting damaged.

    Never saw any instructions or warnings against this practice ... but it seems kind of logical. Is this by any chance a known problem with the 250 and finger tip control? Did I just get unlucky and come across three bad boards with all the same components burning out? Anyone else have a similar issue?

    I was thinking of not running the control cable along the power cable this time ... .but that makes a mess when you are crawling around trying to get some work done.

    Last edited by dataway; 07-24-2020, 01:50 AM.

  • #2
    I have nothing for you except I have used a finger control on mine a few times with no issues. Could never get used to it.
    Trailblazer 250g
    22a feeder
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    Victor O/A
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    Whitney 30 ton hydraulic punch
    Lown 1/8x 36" power roller
    Arco roto-phase model M
    Vectrax 7x12 band saw
    Miller spectrum 875
    30a spoolgun w/wc-24
    Syncrowave 250


    • #3
      Was the finger control made by Miller? Is the control cable shielded? Sounds more like there was a bad batch of components on those boards or a bad design but I for sure can't guarantee that from here. Good luck with whatever you decide to do but a call to Miller might be indicated.



      • #4
        Id give it the middle finger control and not take the chance.


        • #5
          Maybe look into the "tig button". I just picked one up for my Dynasty and have had awesome luck with it so far!


          • #6
            Yep, it was a Miller brand control, still have it, checked it yesterday for shorts, can't find anything. I was thinking about going with an aftermarket control next ... just don't want to take a chance with an $1100 board using the same control again. Actually I might end up selling the machine soon and I don't want to burn out a board before then. Don't do the work I used to, thinking about going with a smaller red or blue inverter machine.

            Like the look of that TIG Button.
            Last edited by dataway; 07-25-2020, 04:21 AM.


            • #7
              Here are a couple of pics. One of some new parts that the Miller tech threw into the box as a "gift" because of my problems. Another of the burnt out resistor on the MB. The resistor has obviously been replaced before and burnt out again ... this was a "new" replacement board. Not sure if my current working board was the same revision number.

              The new module they gave me is evidently obsolete now ... and was a pretty expensive piece. Not sure why they gave it to me, the one in the machine seems to work fine. Don't know if there is a way to test this one ... doesn't appear to have ever been put in a machine.

              Not sure what the bag of parts is for ... perhaps some kind of update or replacement kit. Bear in mind this was all about 18 years ago ... I saved all the parts and documents.

              Click image for larger version  Name:	Miller-Parts-1.jpg Views:	0 Size:	77.4 KB ID:	609824

              Click image for larger version  Name:	Miller-Parts-2.jpg Views:	0 Size:	99.6 KB ID:	609825
              Last edited by dataway; 07-25-2020, 04:24 AM.


              • #8
                What is the assembly number on the board and the resistor number? That resistor looks like it is part of the SCR gate drive section. It's hard to tell what caused it to burn, but I don't see how the trigger switch was causing it unless the high voltage bypass/protection circuit on the remote input wasn't working right.

                The bag looks like a bunch of high voltage blocking/bypass capacitors and one power resistor with leads probably sent out to make sure the arc starter high voltage wasn't affecting the electronics. The blue bypass caps probably match the ones on the back side of your work/ground clamp lug that connect to the chassis. The maroon resistor is probably the one that connects with C3 across the work and electrode lugs to block the arc starter high voltage from damaging the welder electronics and SCRs. I don't know if C3 is made up from those red capacitors in the bag, or if those red caps are meant to be soldered on the board. You should be able to see/compare to the components on the back side of the work/electrode lugs.

                Hope this help,


                • #9
                  Very helpful ... as far as what I can understand
                  Board is labeled KD-39, assembly no. 138307 Resistor looks like R-90

                  Do you know of a way to test that LEM current module? Part No. 156313 with a 9536 sticker, board says 1209-10. Appears to be brandy new, but I'll probably sell it and would like to test it first.
                  Thanks for the help


                  • #10
                    The only way I know to test the lem modules is to power them and flow known current values through them.

                    Quick glance, R90 looks like it limits current in your remote amperage circuit. If you're pedal worked fine with the machine, it could be that there is a short in your finger control plug/connector (across pins C and D). Easy to check with a multimeter.

                    Edit: Re-read, saw you checked the finger switch for shorts. Is it a contactor switch or contractor/amperage control too?
                    Last edited by jjohn76; 07-26-2020, 09:39 PM.


                    • #11
                      It is a contactor/amperage control ... has roll switch ... so like a volume control with an on-off position at the start. I mostly checked continuity between the plug at the switch end, and the amperol plug ... and between a few pins. I'll check it more thoroughly tonight ... I kind of figured since it was probably intermittent that it could take a LONG time to check all the possibilities.

                      I did run across a single post about ten years old in this forum somewhere, poster said that a short (to ground I think) from the 24v remote supply in the touch control remote cable would burn out the board. He didn't elaborate much.

                      I'll check C & D tonight and try to move the cable around while it's hooked up ..... it didn't blow the board immediately ... it was always after a few months of use. The cable has seen better days ... so could be some damage there.

                      Pedal has worked fine for 20 years now.

                      I was hoping for just a typical resistance value between pins on the LEM ... something to that effect. I'll have to assume it's good, looks absolutely shiny and new, was still wrapped in bubble wrap.
                      Thanks again.


                      • #12
                        Yeah, you should be seeing 1k ohms between C and D, and pin E - D resistance should vary from ~0 ohms to 1k ohms. Pins A (power) and B (return) carry the 24V that trigger the contactor/relay, but I am pretty sure that is off the control board on the Syncrowave (relay CR2)- it could burn the traces on the remote filter board or pop CB1 if it shorts though. It could even be something that shorts within the switch when the slider goes through full range of motion. Either way, I would probably call the finger control a loss unless you can find and fix the issues.

                        For the LEM module, it has power/compensation components inside so it can measure AC and DC currents. You could probably do a continuity check from the + to - input (should be open), and from output to ground (should be some nonzero value, looks like maybe 25 ohms?) to give you an idea of the secondary coil and compensation circuit is ok. I think that's about the best you can do without testing it in circuit. Aero, Bushy, or some of the others probably have a better way.

                        Last edited by jjohn76; 07-27-2020, 07:06 AM.


                        • #13
                          Checked the cable last night for continuity between pins. But the way I was doing it I only had a tone for continuity, wasn't watching the meter for values ... got no tone on C and D. I did get continuity changing between too pins when I operated the switch. Did find one spot where the cable had a gouge that tore through part of the braided shield ... but appeared to be no damage to the wiring. I'll check the other values today.

                          To look at this logically ... I can probably assume there is no issue at all with the main board if the pedal has been working fine for all these years. Which leads to me to believe either A: some fault in the finger tip control or B: fingertip control picks up some kind of power surge when taped to the power lead that these boards are sensitive to.


                          • #14
                            it may be worth giving Dave from Tig button a jingle. He has answered the phone every time I've called, is very knowledgeable and may be able to shed some light on your issues. I can say that the tig button so far has been flawless for me and I love that I don't have to rely on a foot pedal when welding out of position.


                            • #15
                              I'll probably be ordering one of those ... but for ...errr.. a new red machine that is on the way I've got the syncro for sale now, just don't need that size TIG welder anymore. I need small things that are easy for my wife to sell when I croak.