FNIRSI SWM-10 Spot Welder Repair
As investigated by u/flyingstoo, this popular hobbyist spot welder has an USB charging chip that is infatuated with failing. This simple repair makes the device once again functional.
Silicone-insulated wires are attached with ring terminals in-between the screw head and washer. This is intentionally unconventional: current flow between the lithium-ion cell and PCB remains unimpeded.
The faulty chip needs to be removed, it’s labelled HOTCHIP PB0063E, located in a corner (underside). It is an ESOP-8 with a pad underneath, making desoldering less simple.
A TP4056 module makes for a safe, slow charger. This one has a Type-C connector.
Wires are routed through an existing conveniently placed hole in the housing.
A small piece of 3M mounting tape fixates the module to the side of the device.
The side cover is then cut and re-attached with the device ready for use.