The plastic coating on "wires" that most people think is insulation, is actually called a smoke fence. People think there is copper underneath the plastic. That's where they're wrong.
Wires are actually filled with smoke. Everything is fine until the smoke gets out. If the smoke starts to leak out, that's when you know there's s problem. If the the smoke comes out real fast, the friction from all that smoke rushing out of the smoke fence (insulation, for you laymen), can cause a fire.
Ask any electrician, find the source of the smoke, and you've found the problem.
Duh!
Soldering paste used to clean the tip of the soldering iron as you make the repair to the board. The snap of the solder sucker as you clean up the board before the repairs. The fun shapes made of the hot solder as it is picked up by the sucker.
Ahhh, the life of an electronics repairman, back when we were actually valuable.