Power Mig 255 gas solenoid

[crumrw]

I have a Power Mig 255 (10986) that is not engaging the gas when the trigger is pulled. Troubleshooting has me looking at the solenoid and the main power board. Has anyone had this problem, and if so, are there any steps I can take to verify where the problem lies?

[ccawgc]

You will need a volt ohm meter. First connect meter leads to the gas valve coil wires. then power up welder.
Set meter to read DC volts. how much depends on your meter. The gas valve power supply is a pulsed voltage (PMW).
If coil voltage is around 36vdc the coil is open and the pcb might be ok. Around 6 to 12vdc coil ok valve is stuck and bad.
If you have wire feed and no voltage to gas valve pcb is damaged. switch to ohms and measure the coil and bad coil will read 0 ohms or open. less than one ohm you will need to replace the valve and the pcb if no voltage is measured.
One test for the valve is to jumper 12vdc to the coil. if it opens its good. Make sure you disconnect the wires to the pcb.
You do not want voltage going back into the pcb. it will damage it. With the coil unplugged measure the voltage on the wires when you pull the gun trigger. should go from 0 to around 36 vdc. If so pcb is probably OK.

[crumrw]

Thank you CCAWGC for the thorough response. I did the test, and I'm getting 24vdc with welder on and not pulling the trigger. With trigger pulled, it drops a couple mV but not significantly. Also, I disconnected the solenoid and applied a 12v voltage to it. It clicked once, and then didn't move/make a sound after that. Any thoughts?

I've purchased the switch transistor that controls the solenoid on the board (IC# IRSF3011). I'm assuming this is probably bad, so my plan is to solder the replacement on the main board.

[ccawgc]

connect the valve to your gas bottle then connect the 12vdc than disconnect. see if gas flows.
Also check the coil and see if it is getting hot. No gas and coil getting hot, coil is bad. it killed the pcb.
Might just be a shorted drive transistor. it is either a mosfet or a darlington pair.
Be prepared to replace other parts on the pcb.

[crumrw]

Be prepared to replace other parts on the pcb.

Ah hell, what else on the pcb could be bad?

[ccawgc]

I see cascade failures on pcbs and in welders all the time.

[crumrw]

Turns out replacing the IC on the board seems to have fixed the issue.

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