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I have an older (read ancient) Syncrowave 300. I have it running off a 100 amp breaker on 2awg wire no plug hardwired to panel. It’s been working fine. Was welding all morning and all of a sudden started tripping breaker. The 100 amp breaker trips before I even strike an arc. I can reset the breaker and turn the welder on and it will power up but as soon as I hit the foot pedal it trips the breaker. I am about to pull the side panel and check the connections at the input wire but if that’s not it any other ideas. Like I said it was running fine ran a bead set up for the next weld hit the pedal and breaker trips.
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Serial number is hk234952 -
Ok update, checked all major connections at the panel and at the welder nothing obvious. Disconnected the torch to make sure I didn’t have some kind of dead short internally in the cheap eBay torch, no change. Turned off high frequency and it still trips immediately. Turned it from high to low output and the dial all the way down as low as it goes. Still trips but maybe takes a half second longer.
Here is the kicker, turned from DC to AC (currently I’m welding mild steel for this project DC straight polarity) on AC the breaker won’t trip. I can even strike and hold an arc just fine although the steel welds like garbage on AC so it doesn’t seem to be an option to continue this way. So whatever is causing my issues appears to only be on the DC side of the welder. I checked and it happens straight or reverse polarity. So any guesses as to where I should go from here? My backup welder is a little Lincoln 110v handy mig. It’s going to be a long project if I have to switch over to that.Comment
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Would suspect the rectifier or a capacitor, call millerweldsupport tech support.
If its the diodes those can be found from one of the electrical component companies or miller4less.
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Is there a direct line to them? All I see on the Miller website is a generic front desk phone number for all needs.Comment
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Sounds like a shorted diode in the main rectifier. Profax is a great place to get diodes great prices.Comment
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You’re going to end up with your hands inside that machine if you move forward with it, so may as well open her up and make sure you’re comfortable working on live electronics or find someone nearby to help you.Comment
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You guys are awesome between guajilloweld’s diagram and Weld Dr’s tip on the diode I think I have it nailed. Just pulled that diode and I have full continuity both directions. I’ll order one tonight. Thanks all!Comment
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Good deal, hope the part isn’t too awfully expensive and it’s in stock.Comment
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$43 shipped should be here by Monday. Can’t beat that for a 45 year old machine, when it died I was thinking it was now a very large paperweight and any parts needed would surely be made of unobtainium I was pleasantly surprised.Comment
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It is best to replace them in pares or even better to replace them all. Careful not to mix them up and keep track of where each one goes.Comment
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One of the most susinct threads in a long while.
Well done OP for the detailed info to kick it off.
Great information from all the Replies.
This is an example of what makes this Forum great
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Just to expand a bit on the WARNING in post#11 - in higher power rectifiers it's fairly common to have diodes with SAME NUMBER, some with an "R" after the number and some WITHOUT - that "R" does NOT mean "rectifier", it means REVERSE - as in, cathode and anode are REVERSED - this is so two OPPOSITE POLARITY diodes can be bolted to the SAME HEAT SINK when creating a bridge rectifier with 4 diodes.
Ignoring the above WILL get VERY EXPENSIVE really fast... SteveComment
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