PC Repair and Maintenance: In-depth Look at Power Supply

• By Scott Mueller
• Feb 28, 2003
• Sample Chapter is provided courtesy of Que

Peripheral Power Connectors

In addition to the motherboard power connectors, power supplies include a variety of peripheral power connectors for everything from floppy and hard drives to internal case fans. The following sections discuss the various types of connectors you're likely to find in your PC.

Peripheral and Floppy Drive Power Connectors

The disk drive connectors on power supplies are fairly universal with regard to pin configuration and even wire color. Figure 3.13 shows the peripheral and floppy power connectors.

Figure 3.13 Peripheral and floppy power connectors.

Table 3.10 shows the standard disk drive power connector pinout and wire colors, whereas Table 3.11 shows the pinouts for the smaller floppy drive power connector.

Table 3.10 Peripheral Power Connector Pinout (Large Drive Power Connector)

Table 3.11 3 1/2'' Floppy Power Connector Pinout (Small Drive Power Connector)

Note that the pin numbering and voltage designations are reversed on the two connectors. Be careful if you are making or using an adapter cable from one type of connector to another. Reversing the red and yellow wires will fry the drive or device you plug into.

To determine the location of pin 1, look at the connector carefully. It is usually embossed in the plastic connector body; however, it is often tiny and difficult to read. Fortunately, these connectors are keyed and therefore difficult to insert incorrectly. Figure 3.14 shows the keying with respect to pin numbers on the larger drive power connector.

Figure 3.14 A peripheral female power supply connector.

Early power supplies featured only two large style drive connectors, normally called peripheral connectors today. Later power supplies featured four or more of the larger peripheral (drive) connectors and one or two of the smaller 3 1/2'' floppy drive connectors. Depending on their power ratings and intended uses, some supplies have as many as eight peripheral/drive connectors.

If you are adding drives and need additional disk drive power connectors, Y splitter cables (see Figure 3.15) and large to small drive power connector adapters (see Figure 3.16) are available from many electronics supply houses (including Radio Shack). These cables can adapt a single power connector to service two drives or enable you to convert the large peripheral power connector to a smaller floppy drive power connector. If you are using several Y-adapters, be sure that your total power supply output is capable of supplying the additional power.

Figure 3.15 A common Y-adapter power cable.

Figure 3.16 A peripheral–to–floppy-drive power adapter cable.