Hobart Handler 140 Mig Welder - Answered Questions & Fixed issues

Cleanliness is important when it comes to Mig welding. Any rust, dirt, dust, oil is liable to be deposited in the whip liner. If it's just a dirty liner you can try cleaning it with a solvent that doesn't leave an oil deposit (electric motor cleaner, brake cleaner, that sort of thing) compressed air and flexing of the whip.

Make sure your whip hasn't been crimped, if it has then no amount of cleaning will restore it to operation.. a new liner is the only reasonable answer.

It's possible that a bad tip can cause feed issues. Miller type tips are the worst, in my experience, sometimes you just get a tip that will weld to the wire when the current passes between them. I've worked in shops where I might go through three tips in five minutes and then hit one that would last all afternoon. If the wire sticks and you can hold the gun up and rotate your wrist and you feel a 'pop' and the wire jumps out of the tip then just change the tip out. Excessive roller pressure with a tip that's sticking to the wire can really make trouble for you. Nozzle dip is your friend sometimes with tip sticking issues.

Copper clad wire is not particularly friendly to liners, the copper is liable to flake off in the liner. I use bare wire, I bag the wire in a plastic bag on the feeder and I wrap a scratcher pad on the wire just before it goes into the feeder and I find that I have few feed issues. Wire that has even a trace of rust should be discarded as it will both fill your liner with rust and give poor quality welds.

lp

The weld wiring burning doesn't meant the transformer is good, it only means you have shorted hot to ground and thats what happens when hot touches ground it heats and melts. I would start by looking for a schematic for you welder. Check and making sure your getting good power to the power supply, relay(s) first. Also you can ohm out the transformer and check for the proper resistance but without the schematic/wiring diagram I can't say what the specs are. Normally on these the power comes in to the switch and then to the relay(s) which send power to the fan, and then splits to the trigger which allows power to the transformer, wire feed motor etc. But without the diagram your just shooting in the dark.

Locate your locale Hobart welding distributer, or contact hobart, the are nice people and will give you all the avice you need.

Hi:Sounds like you have the wrong polarity in your machine. If you are using flux core wire, make sure to connect your ground clamp to the positive side and your gun to the negative side. Dial the right voltage and wire speed according to wire size and metal thickness.Let me know if this help.Regards,D.S.

If you completely remove wire from unit does it still slowdown and stop when you pull trigger?
If yes, then 2 most common problems are
A. Thermistor @ position PTC1 on circuit board
B. Drive Roller Motor

To diagnose, locate thermistor @ position PTC1 in upper middle part of circuit board.
It's yellowish round and about 1/2" in diameter.
Jumper Accross the 2 leads, use a small insulated screwdriver or meter probe.


1. Pull trigger on gun, when motor slows or stops then jumper the leads, if it speeds back up then it's the Thermistor
Replace with a Raychem RXE 1.85A @ 72 v
Or comparable, try EBay

2. If no change, isolate motor by removing the 2 leads and connect a 9-12 volt DC battery source, does motor spin? If not then motor is problem. If motor spins and is constant then additional troubleshooting needed, next possible issues are bad resistor or scr

check main contactor or diode bank.

What have you tried so far?

The transistor is mounted on the main circuit board, you cannot buy the part from Hobart or Miller, they only sell the complete circuit board. If you can read any part numbers from the transistor you can purchase the part from a electronic parts supplier.

bad computer-its an authorized dealer thing-you can pay 1-200 to get it figured out or buy a HF flux core welder for same price. yeah-Im all blue in my shop and I said HF... i would pay the miller dealer to get it fixed.

The first thing to check would be to see if you have open circuit voltage at the weld output terminals when you push the pedal. Make sure the high frequency is off if you are going to to check with a multimeter. After that if you do have OCV but no high frequency to start the arc, try it in start and in continuous. When you put it in continuous it bypasses a control relay. Also check the HF points to make sure they are clean and gapped to about ten thousandths.

Make sure the trigger switch is applying power to the motor. If there is no reading when you checked for OHMS then the motor is open. You'll have to get a new one.

should be adjusters where the wire feeds out to the hose... adjust those. couple of youtube videos online should help you out

Check the selector switch with an ohm meter. Unplug the unit, ground to chassis and probe the contacts while turning the switch on and off.

check the return wire from the hand trigger has been connected to the speed motor wire. Check for a fuse in the system. I have just wrecked a 190 amp welder and I noticed the feed motor assy. was fully insulated from the welder body. Check that out as well as it may be shorting out and not driving the motor.

Check internal connections, Check to see if CR3- a heavy 24 volt contactor- closes. And check for continuity of secondary winding of transformer which connect to the rectifiers. The rectifiers are likely dead, or contactor has failed- either the coil winding or the contacts. Bypassing therectifiers will allow machine to work as an AC weldert, but your results may be unpredictable.Also check for continuity between pins 1 and 4 on heat selector switch (primary windings in series, you should see some resistance, but not a great deal).

There are two wires comming from the circuit board to the wire feed motor. You can try running the motor directly from a 12v battery or two for 24 volts. You might want to look at the name plate on the motor to check the normal DC current it draws. If you do not have an ammeter, you could use a fuse close to or just under the normal current. If it runs and draws too much current, then you know you have motor problems.If it runs well and draws a fraction of normal current,you know the motor is good. Before you condem the circuit board, check that it is receiving the correct input voltage. If the welder is dual voltage,then somebodys mistake making voltage change could send 240 v to the board that is meant to receive 120v. Hope this helps, Robert

A schematic would certainly help, give Hobart a call and ask for a wiring diagram. or manual. Hobart are very helpful and may even give you guidance, you may have to pay the postage, they usually fax these documents so it will not cost you anything.

Does it just do it once for a short time each time the machine is plugged in? If so, don't worry about it.

lp

Have you checked the trigger inside the gun to make sure it is not stuck?

Feed wheel tension is a little bit too tight, or the liner may be damaged.