A PCB, or Printed circuit board, contains a large number of electronic components that are interconnected through thin copper traces. The distance between these traces is generally very small, on the order of less than 1/2 millimeter. Such a short distance makes the side-by-side traces prone to shorting, that is getting electrically connected with one another. An electrical short in a circuit may degrade its performance, make it nonfunctional or damage its one or more components.
1 Inspect the circuit board under a magnifying glass for shorts. Closely look at all traces and all component pins for any possible place where shorts could have occurred. Mark all the places on the board that you suspect of having electrical shorts with a marker.
2 Turn the multimeter on and set it to the continuity test mode. This can generally be done by turning its knob to a point labeled with three or four curly parallel lines. Insert the red multimeter lead in the socket labeled "V" and the black lead in the socket labeled "COM."
3 Place the tip of the black multimeter lead on one of the two conductors that you suspect of having short and place the tip of the red multimeter lead on the second conductor. If there is a short between the two conductors, you should hear a continuous beep sound from the multimeter. Repeat this process for all the conductors you suspect of having shorts.