Learning Resources

Disk Drives Connectors

The desktop computer hard-drive connector is pictured here. It has 4 conductors, with the standard pinout as follows:

Pin # Color Function
1   Yellow +12 V
2   Black Ground
3   Black Ground
4   Red +5 V

Sometimes, especially in older computers, the colors differ. The pins are 0.200 in (5.08 mm) apart (center to center). The connector housing has chamfered corners on one side to prevent the user from plugging it in incorrectly. The connector that provides power (e.g., on a power supply) has female pins and a male housing; the connector that receives power (e.g., on a peripheral) has male pins and a female housing.

The connector is standard on all PATA disk drives and low-end SCSI disk drives; however, newer SATA disk drives will employ a more advanced interconnection with 15 contacts. These new, advanced connection systems are being developed by Molex and other connector companies, often working together to develop interconnection standards.

Despite its widespread adoption, the connector has problems as a 30-year-old product. It is cumbersome and difficult to remove because it is held in place by friction instead of a latch, and some poorly constructed connectors may have one or more pins become unattached from the connector when plugged in.

Insertion may also be difficult due to the tendency for the loosely inserted pins to come askew, preventing easy insertion into the female connector.

Additionally, over a long period of time the receiving socket can spread, making the connection imperfect and subject to arcing. It is strongly advised that, whenever working with these connectors, you check for any sign of blackening or browning on the white plastic shell: This is often a sign that arcing is happening and the connector needs replacing. In extreme cases (for example in vintage pinball machines which often use this style of connector) the whole connector can melt due to the heat from arcing.

An image of disk drive connector is -