20 Most Recent Hobart Welders 500505 Handler 140 MIG & Flux Cored 140 Amp Welder w/Cart - Page 5 Questions & Answers

a broken or loose main lead or burnt out armature.

Make sure the switch for remote power or control at machine is on the right setting. It will arc but very faint if this switch is not on the right setting.

set parameters,check voltage and amperage properly

change the cutting nozzle

Try increasing the feed rate. Decrease voltage also. If still no luck, try checking the wire diameter. If you are using flux core wire, make sure the wire isn't too old and it hasn't been exposed to moisture. If you are using gas, make sure that the gas regulator is working properly. If so, then try getting closer to your work with the nozzle. Distance from your workpiece and wind can interrupt the gas shield, causing the wire to burn unshielded.

Check the 24 volt contactor terminals, the contactor may need replacement. You need to determine if power from the control board is reaching the feed motor. If it is not- the SCR's on the control board have probably failed. They are an easy replacement, but it is a stinky process as Miller varnished the boards. It is going to be a pulsed waveform so an analog meter will work best, set on AC and slowly lower voltages on the knob starting from 250 VAC and going lower until a response is noted as needle deflection, the needle will jump off zero if there is power.

Looking at the Hobart manuals, that is how they set them up at the factory.One way to make a change to that is to wire in a solid state relay or solid state Triac and pick up an energizing voltage off of location RC2-1 or RC2-2 on the control board when the trigger is pressed, or as an alternate location from the feed motor through a resistor and rectifier. Once you know if the voltage goes low, or voltage goes high at your point of signal, you pick the contact you want on the relay so when the wire is feeding out, the gas is flowing. and when it is not feeding wire out, the gas is shut off.

http://www.hobartwelders.com/om/6digit/o235281b_hob.pdfThey do not list the board level components usually because they just replace the entire board doing field repairs or refurbishing.If you replaced the SCRs, if you used the same brand or equivalents, there should be some visual clues on the board, or just check to make sure the incoming power goes to the anodes of the SCRs and the output to the motor is the cathodes.

Usually I would start by replacing the head components first to ensure that its all clean and that I would be able to initiate an ARC when I needed.if that failed i would then disconnect the unit and ensure its clean INSIDE.Note that this is usually done by a qualified person as high voltage can kill !DO NOT USE COMPRESSED AIR UNLESS IT IS DRY AIR, NO OIL OR MOISTURE AND PRESSURE CAN BE REGULATED DOWN TO AROUND 20 PSI !!Vac out heavy debris first and blow out remaining in a ventilated area preferably outside.Check the boards for any signs of overheat and inspect further if overheat issues are noticed. esp. on the track sides of the pcb's.Check internal connections too while you are there for any that may seem slightly melted or warped with heat.Other than those simple measures you are looking at tracing with meters etc.But as is normal there is no MODEL !Oh well another BOT question no doubt.

Hi:
Here's your link for the owner's manual:
http://www.hobartwelders.com/om/0400/o494f_hob.pdf

Regards,

Hi:
Have you disconnect the gun's power plug? If the wire and gas stop flowing by doing this action, then your problem is the gun's trigger. If the machine continues to feed gas and wire with the gun disconnected then yes, it is the pc board.
Good luck.

Hi:

If you see rust on the wire then you should stop and change the gun's liner, change the contact tip and clean the feed rolls. Rust can accumulate inside the gun and make the wire feeding a problem.