Components of SWITCH MODE POWER SUPPLY (SMPS)

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Components of SWITCH MODE POWER SUPPLY (SMPS) Most of the components used in SWITCH MODE POWER SUPPLY (SMPS) can be easily identified. However, some components are difficult to identify. Some components are designed especially for a particular model. The

Components of SWITCH MODE POWER SUPPLY (SMPS)

Most of the components used in SWITCH MODE POWER SUPPLY (SMPS) can be easily identified. However, some components are difficult to identify. Some components are designed especially for a particular model. The different components of SWITCH MODE POWER SUPPLY (SMPS) are:

Switch Mode (chopper) Transistors and other Semiconductors.

A transistor is small and fast semiconductor used for amplification and voltage stabilization.

Bipolar Power Transistors (often BU or 2SC/2SD numbers.) High voltage power transistors, which are used as the main switch mode transistor.

Diodes and Rectifiers - AC line rectifier uses a combination of 2 or 4 diodes. High efficiency diodes are used to rectify output voltages. These diodes look like normal axial lead diodes. They can be combined in pairs inside TO220 type packages. To troubleshoot SWITCH MODE POWER SUPPLY (SMPS) problems, test for shorted and open junctions.

Capacitors (filter and bypass) in an SWITCH MODE POWER SUPPLY (SMPS)

Filter Capacitors - Used to filter the rectified AC line input voltage and various outputs of the power supply.

Bypass Capacitors - These are green colored, high quality plastic dipped or rectangular molded capacitors part of RFI filter. They are placed at output section and seldom fail.

Resistors - Test for proper value with the help of multimeter. While measuring the resistor in-circuit, if the value is higher than normal value, then resistor is bad.

Startup Resistors - They are high value (100K) medium wattage resistors. Test for open circuit results in dead supply without blown fuses or fusable resistors.

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Posted on Sep 11, 2011