Cold Ground Or Hot Ground?
Many of us sometime confused about the difference between the cold ground and the hot ground. It is easy to differentiate between the grounding. If you repair the switch mode power supply you will definetely see the biggest electrolytic capacitor in the primary side. It is usually rated at 150uf -330 uf with 400 to 450 volt. Look at the negative sign on the sleeve of the filter capacitor. That negative sign point to the circuit track and that track is the “Hot ground”. The cold ground is the ground that comes from the 3 pin plug. If you still don’t understand, then look at the filter capacitors negative sign at secondary side of the power supply. The negative sign is actually pointing to cold ground!
If you want to measure the voltage at the primary side of switch mode power supply, place the meter ‘s black probe to hot ground and if you want to measure voltages at secondary side then place the black probe to cold ground. If you don’t place it accordingly, you may get inaccurate result or may even burn the meter. So be sure to which ground you should put before measuring the voltages of electronic equipment.