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Syncrowave 300 - HF runs constantly.

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  • Syncrowave 300 - HF runs constantly.

    Hello all. I'm hoping someone here can offer some insight into this problem.

    I have an older (70's) Syncrowave 300 Serial # HF870922
    Approx 30 sec after powering up, HF comes on and continues running. Leaks HF to ground at torch and ground clamp. Obvious items such as settings, switches, pedal have been checked to no avail. HF continues running all the time the machine is powered up despite the settings. I used to be able to weld with AC/HF despite the HF constantly running even before stepping on the pedal but it no longer welds very good at all. Tungsten and collet body turn gray/black and the weld is dirty.

    Some machine history: Purchased as slightly used about thirty years ago. I don't often use this welder and my main use for this machine has been for welding thick alum sections. Always worked well until issues arose with the on/off switch/breaker. Switch wouldn't stay on, like it was immediately kicking the breaker. I could coax it into staying on by repeatedly flipping it on & off until it stayed on in the on position and the machine worked fine. After doing a particularly heavy welding job I could no longer coax the switch and subsequently replaced it. I can't recall if there was any issue with the HF before the breaker situation, may have been, but certainly having issues with the HF now. Don't know if the bad breaker had anything to do with my HF problem but I mention it so as to supply as much background info as possible.

    I'm guessing my problem may be one of the PC Boards but not sure which one or both. I really don't have a clue. Maybe something else entirely. Any thoughts or insight would be greatly appreciated. Thanks


  • #2
    IN all likelyhood, CR2 relay is stuck, time for a replacement...

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    • #3
      Originally posted by cruizer View Post
      IN all likelyhood, CR2 relay is stuck, time for a replacement...
      Thanks for the reply. I'll look into that and see if I can check it out. I'll post my findings.

      More info: When welder is powered up after being off for a while, it takes 15 secs until the HF comes on all by itself. I've had it take as long as 30 secs in the past. If I shut the welder down and turn it back on a few secs later, it only takes about 2 or 3 secs for the HF to start running all on it's own.

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      • #4
        Yep, Cr1 or CR2, likely the latter

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        • #5
          Is this the CR2 relay?

          Click image for larger version

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          Looking at the circuit diagram it appears this is in the remote contactor control circuit, correct?
          If that's the case, why would it come into play when the settings are set to panel control?
          Also, when set to remote, I don't get any welding current until I step on the pedal but HF is running all the time.
          HF runs continuously even with machine set for DC with HF switched off. Still thinking CR2?
          Thanks

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          • #6
            He thinks the relay is stuck on, all the time, regardless of panel switch positions.

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            • #7
              OK. As long as the CR2 relay is the one I have pictured, I have one on order. Probably won't have it in my possession till next Monday.

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              • #8
                I can't comment on whether that is CR2 or not-just don't know. I can tell you that Cruizer is seldom wrong. He has seen a LOT of machines through his shop.

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                • #9
                  Originally posted by cruizer View Post
                  Yep, Cr1 or CR2, likely the latter
                  Alright, that's not it. What else you got?

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                  • #10
                    your machine probably has several relays in it, are you sure you replaced CR2?

                    I'm having a relay problem with one of my machines currently. That machine has at least five relays, four of which are clustered together (CR1-CR4) and they look identical but all have different specs.

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                    • #11
                      According to the Service Parts Manual I received a couple days ago, yes I have the correct relay. The one I have pictured IS the CR2 Relay. The CR1 Relay is next to it and it's different in that it's an open DPDT verses the CR2 which is an enclosed 3PDT. I replaced the CR2 with a new one I received today and the CR1 can be manipulated by hand being it's not enclosed. None of it made a difference. The HF still runs continuously as previously stated. Any suggestions?

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                      • #12
                        Does the HF run with the foot pedal unhooked?..Bob
                        Bob Wright

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                        • #13
                          Originally posted by aametalmaster View Post
                          Does the HF run with the foot pedal unhooked?..Bob
                          Yes.
                          Unhooked with machine set to remote and the HF switch turned off. Also with any combination of switches and settings.

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                          • #14
                            My next guess would be a shorted Q301 Thyristor on PC2.

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                            • #15
                              Originally posted by Aeronca41 View Post
                              My next guess would be a shorted Q301 Thyristor on PC2.
                              OK. That sounds more like where I thought I'd be going. I may take a shot at replacing them, but looking into the PC2 boards raises another question. My machine has an older 039 195 board (mine is actually marked 039 196) as shown in the parts list from a 1975 owners manual. The Service Parts Manual I received a couple days ago is dated 1991 and does cover my serial number machine. On the subject of the PC2 Board the manual states for 052 790, the only PC2 Circuit Card shown, "This Circuit Card Replaces All Previous Circuit Cards And Is The Only Card The Factory Recommends Repairing". I notice there are no transformers, relays, or thyristors on this newer Circuit Card. I'm wondering if updating is the way to go. Thoughts?
                              Last edited by Sked; 09-23-2016, 05:10 PM.

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