The heating elements housed inside the cartridge style tips have a lifespan. After a period of use, they will eventually expire and require replacement.
Sometimes, dropping a tip will cause it to blow either immediately or the next time it is used. Whilst the tip casing is robust, the element inside is fragile and likely to sustain damage if dropped.
It is possible to determine the status of the element inside the tip by reading the Ohms as shown in the image below.
Note that an infinite or open circuit reading between these two points is also a sign that the heating element has expired.
Normal function of the soldering iron can be restored by simply replacing the tip with a new one. We carry a range of cartridge style tips HERE.