The electric iron is energized at the tip is not hot, don't spend only the solder, solder to solder to put electric iron base solder is open, use the pointed end of the electric iron, it not at the tip at the soldering temperature is not enough, is how it happened
Is not hot but heat oxidation, find the center with wire or welding oil rosin, with a knife scrape iron head rapidly with tin wire or rosin OK.
It is winter, the use of low environmental temperature, plus the reasons described above, plus wattage watts slightly lower reasons, you can say that the failure of the statement. The rest is the electrical principle, the line has virtual connection, and the heating body internal resistance silk virtual connection. Or there is not enough
Usually this is due to the oxidation of metal iron head of the reason, the oxide layer relatively poor thermal conductivity. We will be in the use of iron when the first dip rosin to prevent oxidation, if have oxidation, can use sandpaper grinding head. Personal life experience, may not be professional, I hope to help you
