- Disassembly Overview
- Electrostatic Discharge (ESD)
- EMI (Electromagnetic Interference)
- Disassembly
- Tools
- Opening the Case
- Cables and Connectors
- Storage Devices
- Motherboards
- Mobile Device Issues
- Reassembly
- Preventive Maintenance
- Basic Electronics Overview
- Electronics Terms
- Power Supply Overview
- Power Supply Form Factors
- Purposes of a Power Supply
- Power Supply Voltages
- Mobile Device Travel and Storage
- Mobile Device Power
- ACPI (Advanced Configuration and Power Interface)
- Replacing or Upgrading a Power Supply
- Symptoms of Power Supply Problems
- Solving Power Supply Problems
- Adverse Power Conditions
- Adverse Power Protection
- Surge Protectors
- Line Conditioners
- Uninterruptible Power Supply (UPS)
- Standby Power Supply (SPS)
- Phone Line Isolator
- Electrical Fires
- Computer Disposal/Recycling
- Soft Skills?Written Communications Skills
- Chapter Summary
- Key Terms
- Review Questions
- Exercises
- Activities
Power Supply Voltages
Refer to Figure 4.21 and notice how +3.3, +5, –5, +12, and –12 volts are supplied to the motherboard. The motherboard and adapters use +3.3 and +5 volts. The –5 volts is seldom used. If the motherboard has integrated serial ports, they sometimes use +12V and –12V power. Hard drives and optical drives commonly use +5 and +12 volts. The +12 voltage is used to operate the device motors found in drives, the CPU, internal cooling fans, and the graphics card. Drives are now being made that use +5V motors. Chips use +5 volts and +3.3 volts. The +3.3 volts are also used for memory, AGP/PCI/PCIe adapters, and some laptop fans. The negative voltages are seldom used.
A technician must occasionally check voltages in a system. There are four basic checks for power supply situations: (1) wall outlet AC voltage, (2) DC voltages going to the motherboard, (3) DC voltages going to a device, and (4) ground or lack of voltage with an outlet tester. A power supply tester can be used to check DC power levels on the different power supply connectors.