80€ at Lidl. I'm not a good (stick) welder, and a good welder will not make me a good welder. Looked at the more expensive one (140€) which does everything, but only seems to be sold in Belgium. Disposable gas bottles last 15 mins according to plenty of forums and at 25€ a pop, that wasnt going to happen. I could hire/buy a bottle, but I weld maybe 10 times a year. Gasless was the way to go for me. And after a bad start I'm happy with the results.
The main circuit is very similar to this one https://www.instructables.com/id/MIG-Welder-Repair-and-Mods/ but it is AC output, and the speed control is more complex. All the pin numbers and AC correct on this one. https://www.reddit.com/r/Welding/comments/amsy7p/help_can_someone_please_explain_the_wireing/ Mine uses the welding supply to drive another bridge, and the drive is 24V, so ignore all the electronics.
When you press the trigger, you complete the AC circuit from a small 12V trafo on the pcb, which drives a large relay and a small relay together, so you should hear a click. I had no click. The large relay feeds the large welding trafo. The small one runs the feed motor via a 4069UB chip, pot + SVF740 mosfet
I removed the PCB, and the 1/2A fuse, and put a 12V psu on the fuse and pin 4. Doesnt matter that it's DC as the next device is a bridge rectifier. Nothing. Tried on the relay. All good. Kept working back and it was a dry joint on the bridge. Looked fine, but a quick re-heat and all good.
I repair quite a lot of stuff and this is by far one of the best pcbs I've seen in cheap gear for a long time. They could be fake parts, but they are branded, and the soldering is err good. I think it's hand soldered, but it looks like lead to me, not ROHS - way too shiny. A good layer of conformal coat too...all over the connector too!
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| harbor freight flux 125 |
I might look at changing to DC - see here
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