Power Supply, Cooling System And SMPS Troubleshooting at ALL IT Knowledge

Power Supply, Cooling System And SMPS Troubleshooting 

Power Supply

• Accepts the Alternate Current (AC) supply from the power socket in the wall and converts the AC supply to the Direct Current (DC). Now a days power supplies are available in the range of 250W to 400W
• Supplies 3.3V, 5V, and 12V to the different components of the system

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Functions of the Power Supply

• Converts AC to DC to supply various components
• Generates high-frequency signals during the electric current conversion from AC to DC
• Packed in a metal box to prevent damage to system due to high-frequency signals

Output Voltages

• Various voltages provided by the power supply are:

1. -12 V (Blue) – required by some of the serial ports
2. -5 V (White) – required by some older floppy controllers and ISA bus cards
3. 0 V (Black) - ground
4. +3.3 V (Orange) – required by processor, DIMMs, PCI/AGP cards
5. +5 V (Red) – required by voltage regulators, ISA cards, SIMMs and disk drive logic
6. +12 V (Yellow) – used by drive motors and cooling fans

Power Supply Control Signals

• Power supplies are operated using different control signals
• Different control signals are:

1. PG Signal (5V Grey)
2. Power-On (PS_ON) (5V Green)
   +5VSB (Violet) – Always on when AC power input is active, even if the system is turned off

Form Factors of Power Supply

• Represents size and shape of the power supply
• Must match the form factor of the system case and the motherboard
• Different Form Factors:

1. Advanced Technology Extended (ATX) – Uses NLX power supply. Does not have a power outlet to connect to monitor.
2. New Low Profile Extended (NLX) - NLX motherboard also uses a riser board for the expansion of bus slots and uses true ATX power supplies. 
3. Small Form Factor Extended (SFX) – Has two fans to cool the whole system. The output of SFX power supply unit is 90W and is used on smaller systems that do not require a lot of power. 
4. Low Profile Extended (LPX) - Is also known as slimline form factors because its cases are known as slimline cases. The main goal of this form factor is size reduction. 

Components of the Power Supply

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• Power supply unit consists of different functional components
• Different components of the power supply are:

1. Power Connectors
2. Power supply Fans

Power Connectors

• Electrical connector used to carry DC or low frequency AC power
• Connectors carrying small amount of power are called signal connectors 
• AT Power Connector - Two 6 wire connectors named P8 & P9 which are to be connected to the mother board with black wires inside. PC/XT, AT, Baby AT and LPX form factors use AT power connectors
• ATX Power Connector – 20/24 pin single connector with mainly 6 types of voltages coming out of it. ATX/NLX form factors use the ATX style power connectors  
• ATX Power Connector - 24 pin SMPS connector is built with ATX style of power connector.
• 4 additional pins number 11, 12 and 23 carry the voltage +12 V, +3.3 V and +5 V respectively. Pin number 24 is connected to the Ground. 
• Standard Peripheral Power Connector (Molex) - Use 4 wire connectors. Hard disk drive, CD/DVD drives use this larger size connectors
• Floppy Drive Power Connector (Mini/Berg) -  3.5-inch floppy disk drive use smaller size connectors, called as mini-plug 

PCI-E Connector

PCI-E Connector

• Is a 6 pin connector used to provide extra 12 volt power to PCI Express expansion cards. PCI Express motherboard slots can provide a maximum of 75 watts. Many video cards draw significantly more than 75 watts so the 6 pin PCI Express power cable was created. 

Power Supply Fan

Power supply fan

• Used for cooling the system
• Located at rear end of power supply unit
• Ball bearing fans are more reliable and are long lasting as compared to sleeve bearing fans

Factors to be considered before selecting power supply

• Size – Should fit in your system case
• Connectors – No. of connectors should be more
• Wattage – Computers have rating between 300 – 350W and servers have rating 350 – 400W

Types of Cooling Systems

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1. System produces heat while it is functioning that can damage the internal components of the system
2. Fans - System case and the system power supply have a fan in it that helps channel air flow in or out from the system case 
3. Heat sink - Heat sink is used to cool the microprocessor and the other chips on the system
4. Thermal grease or heat sink compound - Thermal paste or heat sink compound is a fluid substance with grease properties.
5. Liquid submersion cooling - In this system, all the computer parts are submerged in a thermally conductive liquid. This liquid must have low electrical conductivity in order to make sure that, it will not interfere the normal operation of the computer components.
6. Liquid cooling system - Liquid cooling is a radiator for the CPU. Liquid cooling system circulates a liquid through a heat sink to the processor of the computer.
7. Heat is transferred from the processor to the cooler liquid. This hot liquid moves out to a radiator at the back of the case.  The radiator transfers the heat to open air outside the case. The cooled liquid is then transferred back to the system and the process continues.

Air Flow

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• Use an ATX form factor system - Due to the flow direction of the air from the ATX power supply unit, this form factor is preferred.
• Use a large system case – A larger system case allows better flow of the air in the system.
• Arrange the internal components – Each component should be placed approximately ¼ inches apart from each other.
• Keep the system clean –This protects the system from air blocks due to dust.

Troubleshooting

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• Various tools can be used to troubleshoot SMPS problem
• Due to a faulty power supply, the components of the system may also get damaged
• Problem that may occur are:

1. Power Supply Fan does not Work or Emits a lot of Sound
2. Before Opening SMPS
3. Troubleshooting PC problems without opening SMPS