What should I do if my soldering iron tip turns black and stops melting solder?Updated 2 days ago

This is called "oxidation." It happens when the tip is left hot for too long without use. To fix it, you need to "tin" the tip: while hot, gently rub it against a brass wool cleaner or a damp sponge, and immediately apply fresh solder. To prevent this, always turn off your iron when not in use and leave a small blob of solder on the tip to protect it.