My welder is tripping the breaker when the trigger is pulled. This does not occure every time, but quite often.

SOURCE: MIG wire is always hot without pulling trigger

Check your manual, there are a lot of mig units on the market that are alway "Live" alternatively, the relay has either shorted or you have wirering problem on the switch.

SOURCE: I have a Hobart 135 Handler wire feed welder that

Get a volt meter, go to ohms setting , check transformer to ground for low to zero ohms reading. also look closely at transformer windings for foreign objects in between them, never know what you my find. If transformer is shorted to ground probably time to say some nice words over it before burial. Also just for kicks try a new gun on it, (there is a reason i'm asking you to do(this) see if you can find someone that has spare. A good honest repair shop would probably be reasonable if all else fails. to a least let you know if the transformers a problem. good luck

Signed
Former Miller Certified Tech.

SOURCE: When pulling the trigger it trips 20 amp breaker.

You have have an earth fault. have it tested for your own safety.

SOURCE: My Hobart Handler 120 stopped

Please don't give me a bad rating for this. Its just a little extra info. you didn't mention that may help you find the problem. Depending on your specific model, there should be 1 or 2 breakers on the unit it self. If there is only 1, it will shut down the entire machine when tripped. If there are 2, the top one is for the whole unit and the lower one is for the wire feeder motor only. There is also a thermal overload that will shut down everything except the cooling fan. Secure the trigger closed and let the fan run for a while to see if it re-starts when cooled. If the depth of the weld was stable before the problem occurred, I would suspect a short in the motor and not the rectifier. That is not a sure bet though. If the transformer does not start when it cools, UNPLUG the welder and short the transformer to ground to be sure the capacitor is discharged. Then isolate the feed motor and transformer and use an OHM meter to test them individually to ground for a short. With a little luck, it will be the feed motor. Please let me know if this helped at all. I am new and still learning how to explain what I am thinking. Thanks for writing us.
Roger

SOURCE: i have bought a ya205

probably circuit board, i might have one , email me user name hoss805 on layitlow.com