One morning, I decided to see about repairing the old military battery charger. The tag said the switch timer was bad but it turned out that the crimp connector on one of the wires going to the ammeter was intermittent causing no reading, so the appearance was that it was not charging. That was a fun little exercise.
We also investigated an old inverter welder. It had no case (The case had been taken by a previous owner of this junked equipment to use as a stool long before Brian dug it out of a dumpster) and was a 480V 3 phase unit. We cleaned mud dauber nests off the circuit board using a screwdriver and then some brake cleaner and a wire brush and rewired it for 240V single phase. Then we connected to to single phase power (notice the 240V cable rigged in the vise). That was fine because it had a fullwave bridge and large filter bank, but the unit had some issue with regulation possibly due to a burned resistor we could not identify. This machine made some really interesting noises as though it wanted to blow up while trying to weld. The video shows this and it is well worth watching.
21MB higher quality version of the video as shown in sample on right