VIDEO CONNECTORS

All computer monitors have at least one thing in common: they all connect to a female DB 15-pin port on the back of a computer system. (Figure 21.1 shows a standard female DB 15-pin video port on the back of a system unit.) The DB 15-pin port may be attached directly to the motherboard, or it may be located on a video expansion card.

The female DB 15-pin port has three rows of five pinholes that accept a male DB 15-pin connector, which is attached to the end of the monitor’s cable. Each of the 15 pins on the monitor’s DB-15 connector has a different pin assignment that carries out a specified video function related to power, color, or refresh rate. Many monitor-related problems can occur if one of these pins gets bent or broken. It is very important to take great care when connecting a DB 15-pin connector to a DB 15-pin port on the back of your system. Table 21.1 displays the functionality of each of the 15 pins on a DB 15-pin video connector.

Table 21.1: Individual Pin Assignments for a DB 15-Pin Video Connector

Pin Number	Video Function
1	Red video
2	Green video
3	Blue video
4	Monitor identification 2
5	Ground pin/unused
6	Red video return
7	Green video return
8	Blue video return
9	Unused
10	Ground
11	Monitor identification 0
12	Monitor identification 1
13	Horizontal synchronization
14	Vertical synchronization
15	Unused

The A+ Core exam is likely to present you with a question or diagram that tests your knowledge of the difference between a DB 15-pin video connector and a game/MIDI port, otherwise known as a joystick/MIDI port on a sound card. (See Figure 21.1 for the location of a game/MIDI port on a system unit.)

Note

Remember for the exam that a female DB 15-pin video port has three rows of five pinholes. A joystick/MIDI port on a sound card has two rows of pinholes: one row of eight pinholes and one row of seven pinholes.