So I decided to turn on my older transformer mig welder that has sat idle for a couple of years, it was working fine when last switched off. The machine powers up but the wire feeder is dead. I have wriggled wires and measured a few voltages and the board is getting power but nothing happens when I pull the welding trigger.
The board gets fed 24V AC power, and I have gone so far as measuring 34V on the board after the bridge rectifier. The board does multiple things. When you pull the trigger on the welding handpiece, it should send voltage to a gas solenoid to turn the gas on. It should send voltage to the wire feeder motor to feed motor, which I suspect is via PWM, it also send voltage to turn on a main contactor for the welding transformer.
The board has inputs of a potentiometer for the wire speed, a burnback potentiometer that means after the trigger is released the wire feed is cut the welder still welds for a fraction of a second more. and a toggle switch to control what happens when you pull the trigger on the torch, either a simple on/off, press once for on and press again for off.
The board seems in good condition and there are no obvious faults, all through hole, double sided tracks.
I am not sure where to start trouble shooting due to my inexperience. I can solder desolder through hole stuff OK. Have multimeter, DC power supply and oscilloscope on hand.
Since nothing works I would suspect the power supply side of the board. I am sure it is repairable especially as I assume it is all analogue.