There are two main types of capacitor faults: open circuit and breakdown. In addition, the breakdown can be partial (then it is called leakage) or occur only at a certain voltage). Also, the capacitor may lose capacitance or its equivalent series resistance may increase.
Instructions
Step 1
Check any capacitor in a completely discharged state, while both of its leads must be disconnected from any other circuits. Failure to do so can result in electrical injury and equipment damage.
Step 2
Connect an ohmmeter to the capacitor (to the electrolytic one - in the correct polarity). At first, a current should flow through the device, but after charging it should stop. In capacitors of small capacity, it turns so quickly that the ohmmeter does not have time to react. A finger-type battery connected in series with the headphones will help. This probe must be connected to the capacitor several times. If the click is heard only during the first connection, the device is working properly. If the current continues to flow, a breakdown occurs, and if not even charging occurs, an interruption occurs.
Step 3
To detect intermittent breakdowns that occur only at operating voltage, make a circuit from a voltage source equal to the operating voltage for a capacitor, a milliammeter, and a load that limits the current to a safe value. Also connect the electrolytic capacitor with the correct polarity. The current must first appear and then quickly decrease to zero. Disconnect the voltage and discharge the capacitor.
Step 4
Check the capacitor for leakage by charging it to operating voltage and then disconnecting it from the power source. After a while, check the voltage across the capacitor with a voltmeter. An electrolytic capacitor should hold a charge for at least half an hour, and any other - at least a few hours. Discharge the component after checking.
Step 5
Check the capacity using a bridge device. Select the limit at which the sound disappears when the bridge knob is rotated. Find the position of the pointer where the sound disappears completely, and read the value of the capacitance on the scale. Compare it with the nominal.
Step 6
To test the equivalent series resistance, use an oscillator operating at a frequency where capacitance is negligible. The generator must generate a sinusoidal voltage so that the milliammeter and AC voltmeter work with the smallest possible error. Divide the voltmeter reading by the milliammeter reading (previously converted to SI) and you get the equivalent series resistance of the capacitor in ohms. The smaller it is, the better.
