Power supply repair guide pdf


Please forward this error screen to 69. They also provide a signal to the motherboard to indicate when the DC voltages are in spec, so that the computer is able to safely power power supply repair guide pdf and boot. The most recent ATX PSU standard is version 2. Several direct-current voltages are required, and they must be regulated with some accuracy to provide stable operation of the computer.

By adjusting the switching time of the transistor, the output voltage can be closely controlled without dissipating energy as heat in a linear regulator. The development of high-power and high-voltage transistors at economical prices made it practical to introduce switch mode supplies, that had been used in aerospace, mainframes, minicomputers and color television, into desktop personal computers. Now all modern computers use switched-mode power supplies, which are lighter, less costly, and more efficient than equivalent linear power supplies. Computer power supplies may have short circuit protection, overvoltage protection, undervoltage protection, overcurrent protection, and over temperature protection.

Recent power supplies have a standby voltage available, to allow most of the computer system to be powered off. This standby voltage is generated by a smaller power supply inside the unit. The standby power source was a small linear power supply with conventional transformer, which was later changed to a switching power supply, sharing some components of the main unit due to cost- and energy-saving requirements. Power supplies designed for worldwide use were equipped with an input voltage selector switch that allowed the user to configure the unit for use on local power grid. Connecting the unit configured for the lower range to a higher-voltage grid usually resulted in an immediate permanent damage.

This is the simple design of a passive PFC. The first active PFC circuits just delayed the inrush. Newer ones are working as an input and output condition-controlled step-up converter, supplying a single 400 V filter capacitor from a wide-range input source, usually between 80 and 240 V. 12 V, but with limited amounts of power. 12 V supply was used primarily to operate motors such as in disk drives and cooling fans.

As more peripherals were added, more power was delivered on the 12 V rail. However, since most of the power is consumed by chips, the 5 V rail still delivered most of the power. An additional wire referred to as ‘Power Good’ is used to prevent digital circuitry operation during the initial milliseconds of power supply turn-on, where output voltages and currents are rising but not yet sufficient or stable for proper device operation. Once the output power is ready to use, the Power Good signal tells the digital circuitry that it can begin to operate.