MIG tripping breaker - somethings wrong with the welder

[chemman]

I have a Century 100 120V welder that is about 9 years old. I used it a couple of months ago with no problems, but when I tried it yesterday, it tripped the breaker when I turned it on. It was on full power setting when I flipped the power switch, so I turned it to 'fan only', turned it on, and then switched it to the lower power setting. The welder will then buzz loudly, the garage lights will flicker until the beaker trips. It is a 20 amp breaker, and I tried another circuit with the same result. I also removed the gun and electrode and the same thing happened.

So, with little to lose, I took apart the welder to see if there is any noticable sign of electrical problems. I took out the reactor/rectifier assemby and the transformer. There is no noticable sign of wear/arcing. I checked all of the connections and wires as well, no problems. I used an meter to check the connections and everything seems to check out.

Does anyone have any ideas what could be causing the problem? I would like to circumvent taking it to a repair shop if possible.

[ss42768]

When you used it a few months ago, did you use it on a different circuit/outlet than the one it's been tripping breakers on? Also is anything else on this 20 amp breaker? Such as a fridge? lights? etc; good luck!

[slamdvw]

Try disconnecting and isolating the leads from the main transformer to the rectifier. Power up and trigger as usual. If you can run it that way, Hook the rectifier back up, disconnect the OUTPUT from the rectifier.

If it trips breaker and has a fit, the problem lies in the rectifer assy... depending on the rectifer setup, it may be possible to test each diode individually.... or maybe not.

Let us know!

[chemman]

Thanks Slamdvw, I will give it a try hopefully this afternoon. It did seem as though the noise was coming from the rectifier/reactor not the transformer. I don't know if will be easy to get to the diodes, there is a plastic cover over them and I couldn't easily pry it off before, but I didn't try too hard either.

[chemman]

It worked just like slamdvw said, disconnecting the transformer inputs to the rectifier allowed me to select power settings and disconnecting only the rectifier output tripped the house breaker as soon as I went to the lowest power setting.

Now I just need to dissassemble the rectifier and find replacement diodes. Looking at it more carefully, it doesn't look too bad to take apart. The diodes don't look like the standard type in more circuit boards. Does anyone know a good place to get them? Radio Shack may now be able to help me on this one. If they are cheap enough (as they should be) I may just replace all of the instead of just finding the bad one(s).

Thanks again slamdvw!!!

[slamdvw]

A picture would be great!!

Just for sake of arguement, who makes century? Maybe they have a parts outlet where a new rectifier can be purchased.

Another option may be to build another rectifier. Mount some monster diodes ( ebay ) on appropriate heat sink material and wire in. Might look funny, but if it works...

me? I'd check manufacturer first. Might get lucky. Failing that, I'd look at alternate routes.

You're welcome, glad to see ya got it narrowed down.

[chemman]

I found out that Lincoln aquired Century a few years ago. I emailed Lincoln to see if they could provide the part, but I won't hold my breath. Once I take apart the rectifier I will do a Google search for something that looks like and fills the electrical requirements.

[prop-doctor]

century--maybe sears?
jcpenny

[gnewby]

I contacted Lincoln some time back about problems I was having with my Century Welder. They did respond to my call, but I didn't gain much from the conversation with the person I dealt with. I ended the phone call feeling like I had spoke to someone about there unwanted child.

I left the conversation with the customer service rep feeling like I was pretty much SOL. No more red welders for me.

[chemman]

Actually, I think I bought it at Builders Square shortly before they closed.

Ok, I took off the rectifier, took it apart, and below are pictures. The diodes look almost like button batteries. There are 6 per transformer line, and I assume (more like guess) that each line coming from the transformer is out of phase from the other, so that the rectified signal going to the feed wire is flat as possible. I checked each of the diodes with my multimeter and only one is bad, as you can see from the scorch marks in the second picture. The bad one works as a contact, allowing current to flow in both directions.

Hopefully Lincoln gets back with me and at least tells me where I can buy a replacement diode. I wonder what would happen if is simply remove the bad one? I have some friends at work who know more about electronics, maybe they will know where I can get one.


5564

5565

[slamdvw]

Those almost look like alternator diodes... try a local alternator rebuild place. Absolute worst they can say is " it wont work"

You can try removing the bad diode, it'll limit your upper current level ( stresses the remaining diodes harder ) I'm sure there are other hazards and problems that will rear their ugly heads.

One thing that *might* need to be done, is remove a diode from the 'good' side. Keep the voltage drop the same. I say 'might'. I could be wrong.

[BobC]

DigiKey has lots of electronic components. You might want to look at their site. I can't tell the size of the diodes from the picture, and I skimmed the text. (Sorry if I missed something), but I did find one diode in a "microde" configuration that might be worth a look. It's on the following page from their on line catalog.

http://dkc3.digikey.com/PDF/T063/0977-1011.pdf

If you called Lincoln's main offices, you might not speak to someone who knows about the Century product line. Try calling their retail customer service line, 800-833-9353.

Good luck

[chemman]

The saga continues...

Lincoln's tech service gave me a phone number for the Century parts depot (1-800-925-7741) and the rectifier part number (860-905-666). I am going to try to get them to tell me the specs on the diodes, then I will just order those instead. I am sure the whole rectifier costs plenty.

[drivesector]

www.alliedelec.com has just about everything in that department, Diodes and crap. They are reasonable and helpful if you call. The specs will definitely help your cause.
Good luck

[Nestor]

Newark.com is another option. They are very well stocked and have a great search engine. Get most of my components there.

[leeschaumberg]

If the welder is tripping the breaker the breaker can not handle the current load. You need to check the breaker first then the welder. Your electric company should have a meter to show you how many amps is being used. Mine does Volts times amps equals watts. your breaker should not trip using 2400 watts. 120 voltsX 20amps = 2400watts . Your welder uses what ever is in your book. Knowing this you now can look at the welder. Not the other way around!:nono:
Lee

[drivesector]

If the welder is tripping the breaker the breaker can not handle the current load. You need to check the breaker first then the welder. Your electric company should have a meter to show you how many amps is being used. Mine does Volts times amps equals watts. your breaker should not trip using 2400 watts. 120 voltsX 20amps = 2400watts . Your welder uses what ever is in your book. Knowing this you now can look at the welder. Not the other way around!:nono:
Lee

Ummm :confused: , If you look up a few posts you will see that the reason his welder is doing this is because he has blown a diode on the rectifier.