Testing Your Printed Circuit Board Components

There are different electrical elements that make up a printed circuit board. These include transistors, capacitors, resistors, diodes and fuses. These components should function properly in order to maximize the performance of a PCB. If one of the components is damaged, the performance might be degraded. Hence, it is important to monitor and test each component.



These are made up of insulating materials. The main function of capacitors is storing energy as electrostatic field. In printed circuit boards, they enable indirect current flow by blocking the direct current flow. When direct current voltage is applied, each conductive plate stores the electric charge. The current flow stops when the capacitors are full. The capacitor type is determined by the insulating material. Some of the insulating materials that are commonly used are silver mica, polycarbonate and ceramic.

In printed circuit boards, the board itself has a capacitor with different layers of power conductor, metal conductive areas and ground conductor, which stabilize a capacitor. The decoupling capacitors in PCBs, on the other hand, reduce the noise and lessen the impacts of some components on the board.

In testing a capacitor, you should remove the other end of the capacitor from the circuit. To avoid overloading of the device, the power of direct current voltage should be matched with the capacitor’s range. When you apply the voltage, there are different possible outcomes. If there is a leakage, the meter reading will register high followed by dropping low again. If the capacitor is open or has too low capacitance, the meter will register no jump.


A resistor is a small electronic device that has two terminals. It is responsible for transmitting electric current to create voltage. An ohmmeter is used to test the resistor. You should first isolate the resistor to establish accurate reading. Next, you should connect the multi-meter to a specific resistor. Then, run a test. If the resistor is open, it will acquire an output value higher than 0.6 volts.


A diode is an electrical device that transmits current in a single direction. It is composed of two semi-conductive materials on both ends: n-type and p-type. While transmitting current in a single direction, diode blocks current in the opposite direction.

P-C-BIt can be a sensitive operation to test a diode. If done improperly, it can cause permanent damage. It is always recommended to seek help from professionals before testing any electrical components. When you are ready in testing the diode, you should disconnect its one end from the board. Next, identify the black and red meter probes with an analog meter. Then, connect the red probe to the anode and the black probe to the cathode. Set the meter reading between 1 and 10 ohms. If the diode is open, the meter will register no reading. If the diode is leaky, the meter will register two readings. If there is a forward bias, the meter will register some resistance.


Fuses are usually located at the PCB input. When there is overvoltage, the materials inside the fuse melt. Thus, it prevents the electric components from getting burn.

Before testing the fuses, make sure that the main electricity is switched off. In testing the fuses, you need to use an analog meter. You should first set the meter to X1 Ohm range. Then, place the probes either way. You can connect the black test probe to one end cap and the red probe to the other end. If the meter registers a reading, the fuse is in good condition. It does not need a replacement. If the meter registers no reading, the fuse might have an opened circuit.