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Key board connectors:

Key boards come with two types of connectors. They are:

1. DIN-5, DIN-5 has 5 pins and used with AT style keyboards.
2. Mini DIN-6, also known as PS/2 connector, has around port with 6 pins, one of which being a square pin used for alignment.

6.Power Supply

DC voltages commonly found in a PC:

· +5, and +12 volts are the DC voltages commonly found on PCs.80386 / 486 operate at +5v
· Pentium and above operate at +3.3v
· Power supply wires - yellow=+12v, blue=-12v, red=+5v, & white=-5v

One good way of determining a bad power supply is that the fan will not rotate. Also, the computer will not boot and the LED s indicating the power and disk activity will be OFF.

ATX12V 2.0 power supply provides four different voltages:

3.3Volts, 5Volts, 12Volts and -12Volts. Previous versions of ATX12V used to provide -5V, and it has been discontinued in version 2.x.

Uninterrupted Power Supply (UPS):

An UPS is required for any critical and un-interrupted use of computers. It has the following benefits:
1. Provide protection against small surges
2. Filters noise from entering the computer
3. Provide power to the computer during line power failure
4. Give stable power to computer, even when the line power is unstable.
Note that the UPS can give un-interrupted power only for a fixed amount of time under a given load, in the absence of line voltage

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