Loss of performance with blown capacitors in a Mig?

[Samuellm]

I have a old 240V Cigweld Transmig. Yesterday I pulled to side off it to replace the gas line and noticed to two of the three large capacitors have started to eject their innards out around the terminals and that the wires linking them have been how as the plastic has melted.

I assume that these are smoothing capacitors for the out put.

As the welder still seems to be operating OK what would be the symptoms of this and how much better would it weld after I find some new ones?


Thank you

Samuel

 

[Fawken]

No idea how much better it would weld. Likely they're filter caps for the initial power supply which means your AC sine wave will be choppy going into the electronics. It would help if you list the model, max amps and if it has both AC and DC output. I found several different models called Cigweld Transmig.

 

[Samuellm]

No idea how much better it would weld. Likely they're filter caps for the initial power supply which means your AC sine wave will be choppy going into the electronics. It would help if you list the model, max amps and if it has both AC and DC output. I found several different models called Cigweld Transmig.

Added two pics the capacitors are in the welding circuit as the earth line in linked in to them.

Thanks

 

[Fawken]

View attachment 431116View attachment 431117






Added two pics the capacitors are in the welding circuit as the earth line in linked in to them.

Thanks

That helps. Those caps look OK as far as I can tell from the pic. Your looking at high resistance joints caused by those crimp on lugs. Cut them off & and solder new ones on after cleaning the lugs on the caps. Filter caps will swell or leak electrolyte when they go out. I don't see that there.

 

[Samuellm]

Thank for that that wire was loose add two more pics showing the leaking around the terminals do you still think that they are OK ?

 

[Fawken]

View attachment 431122View attachment 431123



Thank for that that wire was loose add two more pics showing the leaking around the terminals do you still think that they are OK ?

The one in the middle shows some leakage due to the terminal overheating from the high resistance joint. It will probably be OK once cleaned (clean all of them) but you can likely google the part # and get a new one pretty cheap. What happens on those connectors is they get hot and water condenses on them as they cool. Which in turn leads to more corrosion. Solder lugs are the way to go.

 

[Mysfyt]

That helps. Those caps look OK as far as I can tell from the pic. Your looking at high resistance joints caused by those crimp on lugs. Cut them off & and solder new ones on after cleaning the lugs on the caps. Filter caps will swell or leak electrolyte when they go out. I don't see that there.

X2! Fawken nailed it.

 

[Fawken]

I will add that can type capacitors are easy to test- and you should do so while the case is open. Use an analogue ohmmeter across the two terminals then reverse the leads. The needle on the meter will jump and then drop back to zero if capacitor is good. If a short of more than 5k ohms is present replace cap. Also check both lugs for shorting to the case.