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.

With the console disconnected from mains power and the PSU treated as potentially charged, I resoldered the failed joint with fresh solder.

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 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.

Much better.

And considerably less sparky.

Sources