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Synchrowave 300 need help

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  • Synchrowave 300 need help

    I have a synchrowave 300p in beautiful condition ser#jb-560344. Having trouble with adjustability no matter ac - dc. When in low range I havent enough amperage to form a puddle no matter where I am on amperage control. When in high range its full tilt blowing away what ever Im trying to weld.

    I took it to our miller service people here in san diego and they said they load tested and checked hall device and to the best of their knowledge it must be a pc1 issue but that part is obsolete. pandemic happened and I had to pick up welder.

    Any help would be greatly appreciated!

  • #2
    There are a couple of places that will repair PCBs like that, but it's not always cheap...Innovat is one that comes to mind.


    • #3
      Did they tell you what they checked? The Lo/Hi Range switch doesn't change anything on PC1. It basically just adds another couple coils on the primary side of the hall device, so the board thinks it's providing three times the current. Miller also added a second output inductor in series with the main output inductor, which is needed for the low current arc stability. It may be you have two issues - open circuit (switch S6 bad or bad connections with the second output inductor), and possibly a problem on the PC1 current feedback circuit. The current feedback problem might have even burned out switch S6. It's worth checking continuity from the output rectifier to the output terminal with the switch in Lo. Also worth checking continuity of all four wires from the Hall Device amplifier to PC1. Also, it's worth checking on PC1 resistance from Connector 12 to Pin 2 on IC5.


      • #4
        I appreciate any help. I believe I kind of got the brush off at service center it seems to me that the problem is some how involving the hall device. I am not electronically proficient by any means. jjohn76 I am going to check everything you mentioned and get back to you.

        Thank you both sincerely, Steve


        • #5
          Sounds good. Most of these things you can troubleshoot with a multimeter. If they didn't do what they said, it could either be the hall device, amplifier board (between hall device and main board), or the main board. I think you are running down two issues though, since the amperage control issues are opposite between Hi and Lo range. One thing about checking continuity, it's work checking all connections for corrosion and making sure everything is tight.
          Last edited by jjohn76; 08-02-2020, 11:02 AM.


          • #6
            Hello again jjohn76,
            I have looked up as much as I can trying to figure out what your referring to. As I mentioned I am not that knowledgeable
            concerning electronics. So in restating that I have to ask? what is S6 also output rectifier I dont know how to check for continuity from output rectifier to output terminal. Referring to four wires from hall device only two go directly to pc1 others go to terminal block. Referring to pin 12 to pin 2 on ic5 I got a reading of 5.34 I hope that makes sense.

            Thank you again, Steve


            • #7
              Hi Steve, S6 is your Hi/Lo range spider switch on the front panel. It has 4-larger brass connectors on the back side of that switch. It's worth checking to see if they all look clean or any have corroded. The SCR rectifier looks like a few 1/8" aluminum plates bolted together in an open rectangle. They should have four SCRs and one diode, which are screwed into the plates and have thick electrical cables coming off of them. It's on page 17 in the manual. With the machine turned off and set to DC Reverse polarity, check resistance/continuity (should be close to zero resistance) from each of the plates to the lug for your Tig torch. You should get close to zero resistance for Lo and Hi range.

              5.34 ohms across PC1 connector pin 12 and IC5 pin 2 seems low (5.34 ohms).


              • #8
                I checked the scr rectifier to torch connecter and only two of the plates are reading near zero. bottom plate and short center plate holding diode, two top plates are open. the contacts on all switches appear dirty but no corrosion. hall device amplifier board is quite ugly solder appears disintegrated. I can send pic if you would like.
                I rechecked pin 12 to pin two on ic5 and it reads 5.34 if this is low what might that mean?

                Thank you jjohn76