Made some progress repairing the control board on my welding machine. Replaced the IC’s TL494CN location U1, LM324N location U2, LM317T location U3, TIP122 location Q6, 2N6668 location U8, 2N6292 location U9. Also made some modifications to the board. In case any of these IC’s go bad again I will not have to unsolder and resolder components as I soldered in plugs for U1, U2 and U8. U8 also soldered in a leaded plug and installed another heat sink as I suspected It could have been overheating a bit. I might even install a little 24volt fan to blow on the board to keep it cool. Well hope this will help others with the same problems.
Above was way last week or so.
Today I got my mig welder up and running. Wire feed works great now. After all the electronic components I had replaced, about 16 in all, I still had a problem with the wire feed stopping after about 12” of weld from a cold start. Took the feed motor off, tore it down, found nothing wrong, greased it and put it all back together. It really acted like something was overheating and breaking down, opening the 24 volt circuit. After welding about 12”, I could release and pull the trigger on the gun, the wire feed would start for a second then stop, spit and sputter. So I started checking other items besides the board, what the 24 volt transformer power was going through before it went to the board. Started lightly wiggling wires, all of a sudden one side of the thermal disk broke off, disk is between the two SCR’s mounted to the aluminum plate, this was breaking down and opening the circuit-24 volts to the board. Well I happened to have some disks from past work I have done, drilled out the rivets on the old disk, installed the new one with screws, plugged the wires into it, fired up the welder again, I welded 3 different paths of 12” long welds with no problems, so all the time and effort finally paid off. I now have a good welder that was given to me as they said it was junk. There was quite allot wrong with it. The transformer aluminum leads were melted off at their connections when I first received this machine, so I had to pull the transformer out, cut the melted parts off, there was still enough aluminum lead wire to reconnect them. Took a steel bar and hammer, flattened out the leads, drilled holes in them, reinstalled the transformer and reconnected the repaired leads. It did work and worked well to my surprise. So it took allot of enginuity to get this one going again. Well now I can start welding up the railbed for the sawmill.