How to Troubleshoot a Tantalum Oxide Capacitor Failure

When a circuit component fails, your circuit may have a serious fault.

There are three basic circuit components in an electric circuit: the resistor, the inductor and the capacitor. A resistor resists the flow of current and produces heat, while the inductor resists the change of the flow in current and produces a magnetic field. A capacitor stores an electric charge between two plates and produces an electrical field. A tantalum oxide capacitor is a common and highly reliable type of capacitor. When they fail, you can perform a few tests to determine how the capacitor failed and what this means to the overall health of the circuit.

Things You'll Need

• Multimeter
• Circuit with failed tantalum oxide capacitor
• Wire cutters

Instructions

1. Place the tips of the wire cutters underneath the two leads that connect the capacitor to the circuit. Cut each lead to remove the capacitor from the circuit.

2. Determine the nature of the failure. If the capacitor looks like its burned up or popped open, then a voltage spike is likely the cause. If the capacitor looks fine on the outside, continue with the next step. If the capacitor exploded, skip to Step 5.

3. Place one probe from your multimeter onto one capacitor lead, and place the other probe on the other lead.

4. Turn the dial on the multimeter until it is set to test "Continuity." Some multimeter manufacturers use the diode circuit symbol for this setting, which is why this is sometimes referred to as the "Diode Test." If the LCD readout on the multimeter displays a very small number, then the diode failed due to an internal short-circuit.

5. Decide what to do next. If the diode failed due to an internal short-circuit, then the rest of your circuit is probably fine and the capacitor just needs to be replaced. However, if the capacitor exploded, then part of your circuit is causing a voltage spike. A quick fix to prevent this from happening again is to place a fuse in-line with the capacitor; a surge will burn out the fuse instead of the capacitor. Fuses are easier and cheaper to replace than capacitors.

References

• AVX: Failure Modes of Tantalum Capacitors