I don't know how many of you are familiar with this little wonder: TS100 soldering iron.
It's an amazing little toy (joking) soldering iron that can actually do a proper job, courtesy of its built-in tech. I don't use it often but, since the Magnum station is still in the tool box, I quickly grabbed it to do a small job. While soldering, I felt a slight stinging against my hand . I assumed it was the heat from the soldering iron, so I didn't stop to investigate. After I had done the soldering I felt the temperature of the earthing screw that was the source of the stinging and found that it was not hot at all. It could only mean one thing: the stinging I had felt was a mild electric shock. I measured the voltage on the screw and found it had 90VAC potential. This voltage quickly disappeared as soon as I grounded the earth clip to the anti-static mat.
One would think that, since the power supply (SMPS brick) is supposed to be isolated, there should be no voltage on the soldering iron, but no. This is a problem typical of modern switch-modes: they have X-class filtering caps across the mains that sets their mid-point to roughly half of mains voltage. The junction of the X-capacitors is usually connected to earth. If allowed to float, that is the voltage your soldering iron (in this case) will sit at. This can damage electronic equipment. To be safe, I recommend that you always ensure that your soldering is earthed. In my case there was little risk, as the board I was soldering only had connectors and no electronic circuitry.
It's an amazing little toy (joking) soldering iron that can actually do a proper job, courtesy of its built-in tech. I don't use it often but, since the Magnum station is still in the tool box, I quickly grabbed it to do a small job. While soldering, I felt a slight stinging against my hand . I assumed it was the heat from the soldering iron, so I didn't stop to investigate. After I had done the soldering I felt the temperature of the earthing screw that was the source of the stinging and found that it was not hot at all. It could only mean one thing: the stinging I had felt was a mild electric shock. I measured the voltage on the screw and found it had 90VAC potential. This voltage quickly disappeared as soon as I grounded the earth clip to the anti-static mat.
One would think that, since the power supply (SMPS brick) is supposed to be isolated, there should be no voltage on the soldering iron, but no. This is a problem typical of modern switch-modes: they have X-class filtering caps across the mains that sets their mid-point to roughly half of mains voltage. The junction of the X-capacitors is usually connected to earth. If allowed to float, that is the voltage your soldering iron (in this case) will sit at. This can damage electronic equipment. To be safe, I recommend that you always ensure that your soldering is earthed. In my case there was little risk, as the board I was soldering only had connectors and no electronic circuitry.
