William Sommerwerck wrote:

I once melted a SCSI cable by installing it "one off", thereby grounding the
B+. Fortunately, the computer wasn't damaged.


Most computers have no fuse, outside the power supply so the full
output on the +5 volt rail is available. I sold a used XT computer
years ago. the guy got it home & fired it up. The keyboard cable
caught fire, and melted the +5 volt line all the way from the five pin
DIN connector to the strain relief on the keyboard.