What should I do if my soldering iron tip turns black and stops melting solder?Updated 20 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.