A typical Printed circuit board (PCB) has a large number of active and passive electronic components connected together through copper traces on the board. These traces are very thin, typically less than a millimeter thick and are kept separated from other traces and planes by less than half a millimeter of space. Such thin copper lines are prone to physical damage, including lifting up from the board, cutting and bending. A physical damage to a trace can disconnect the electrical circuit. This discontinuity can be found through a multimeter.
Instructions
1 Insert the red multimeter lead into the socket labeled "V" and black lead into the socket labeled "Com." Turn the multimeter on and set it to the continuity test mode. This can generally be done by turning the multimeter's knob to the position marked with three or four curly parallel lines.
2 Identify the starting point of the connection you want to trace on the PCB. Visually follow the trace up to the first component it connects to. On most circuit boards there are a large number of components and signal traces and therefore it is not always possible to follow a particular trace. However, one can determine a number of possible components it is connected to and then use the multimeter to find the exact component. To do that, first place the tip of the red multimeter lead on the starting point of the trace and keep it there. With the tip of the black multimeter lead, touch all the possible connection points one by one until you hear a beep from the multimeter. The one that produced the beep represents the point electrically connected to the point at which you have the tip of the red lead.
3 Move the tip of the black lead to the other side of the component and keep it there while visually following the copper trace to determine the next component it is connected to. Place the tip of the red lead on each of the possible connection points one by one until you hear a beep from the multimeter. Follow this process until you reach the last point of the trace. The last point could be a point connected to a connector or an active electronic component, such as a transistor or a chip.
