3.4. Recognizing High-Voltage Equipment

High-voltage equipment can cause serious injury if you touch it — it might even kill you. You will not typically service these two major computer components unless you have special training or certification beyond the A+ Certification exam:

  • The power supply unit

  • The monitor

The danger in servicing the power supply and a cathode ray tube (CRT) monitor is that both devices use capacitors that hold an electrical charge even after the component is unplugged. The electrical charge is enough to cause severe shock or electrocution. Beware!

High-voltage equipment usually bears a warning label that indicates that you shouldn't open the component — and, that if you do, you could be severely hurt. Bottom line: You're playing with fire (all right, electricity) if you open these components. Have them serviced by a certified electrician or someone with special training.

3.4.1. Power supply unit

The power supply unit (PSU) is responsible for taking alternating current (AC) from the wall outlet and converting it to a direct current (DC) that is usable by computer components.

The power supply usually takes 120V of alternating current from the wall outlet and supplies the power to computer components by converting the 120 volts AC into 3.3V, 5V, or 12V of DC.

The power supply contains a charge even after it is unplugged, so servicing a broken power supply ...

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