Visual inspection for cracks, bulging, leaking, corrosion, or loose leads
Discharge capacitor before testing (short across terminals briefly with a resistor)
Identify capacitor type and rating (electrolytic, ceramic, film; capacitance value; voltage rating)
Use a multimeter with capacitance measurement mode (if available)
Set multimeter to capacitance (C) mode and select the appropriate range
Disconnect the capacitor from the circuit
Connect multimeter leads to capacitor terminals (polarity-aware for electrolytics)
Read measured capacitance and compare to the rated value (allow tolerance)
Check for open/failed capacitor symptoms with continuity/ohms mode
Set multimeter to resistance/continuity mode
Measure resistance between capacitor terminals
Expect resistance to rise from low to higher as the capacitor charges (for working capacitors)
For a shorted capacitor, resistance stays low (or continuity beeps)
For an open capacitor, resistance stays high (no charging behavior)
Use a multimeter with diode-test mode for quick checks (optional)
In diode mode, observe a brief charging behavior on a healthy electrolytic (varies by meter)
Use an ESR meter (recommended for electrolytics)
Disconnect capacitor and measure ESR per meter procedure
Compare ESR to the meter’s limits or datasheet/expected values
Use a dedicated capacitor tester if available
Follow tester prompts and compare results to the capacitor’s rated capacitance and leakage/ESR specs
For in-circuit testing, confirm power is removed and all relevant components are isolated or interpret results cautiously
Record capacitance, ESR, and leakage/behavior for pass/fail decisions