There are many electronic components on PCBA circuit boards, such as capacitors, resistors, diodes and so on. Among them, capacitors are the most common, so how do we detect bad capacitors on the circuit board?

There are 4 types of bad capacitors:

1. Reduced capacity

2. Total loss of capacity

3. Leakage

4. Short circuit

Method of detecting bad capacitance on circuit board:

1. Check with the resistance file of a multimeter

Use electrolytic capacitors and place the resistance at R×100 or R×1K. Connect the red test lead to the negative terminal and the black lead to the positive terminal.

2. Check the variable capacitor with a multimeter

Use the resistance of the multimeter to check whether there is any contact between a set of fixed pieces and a set of moving pieces of the variable capacitor. Use the red test lead to understand the moving piece, connect the black test lead to the fixed piece, and then rotate the shaft handle. If the meter pointer does not move, it means that there is no short circuit. If the meter pointer moves, it means there is a short circuit.

3. Use the resistance file of the multimeter to roughly identify the capacitance of 5000PF or more

When checking, the resistance range is set to the high value of the range, and the red and black test leads are respectively understood at the two ends of the capacitor. If the pointer moves and then restores and connects in the reverse direction, the capacitor is good after another time.