The Xbox power supply was arcing badly whenever mains power was connected. Once I had it apart, the problem was visible at the AC input connector: a cracked solder joint.

I resoldered the failed joint with fresh solder, and the arcing stopped. So “reflow” is not really the best description of what happened here. I repaired a visibly cracked through-hole solder joint at the mains input.

This is a mains-voltage power supply, so it should be disconnected from AC before inspection and treated as potentially charged even after being unplugged.

This is also not a universal diagnosis for every original Xbox power fault. Microsoft separately ran a power-cord replacement programme for early Xbox consoles because rare internal electrical component failures could create a fire hazard. That broader safety issue is useful context, but the cracked input joint shown here is the fault I actually observed and repaired on this particular PSU.

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