Capacitor electrolytic blown

Blown electrolytic capacitor: causes, identification, and consequences in electronic circuits.

About this subject

Electrolytic capacitors are essential components in power supplies and filtering circuits, temporarily storing electrical energy. When an electrolytic capacitor blows, it is usually due to overvoltage, reverse polarity, thermal aging, or high ripple current. The failure manifests visually through the rupture of the safety vent on top of the can, releasing electrolyte and producing a characteristic smell. In motherboards and computer power supplies, blown capacitors are among the most common causes of malfunction, leading to instability, reboots, and even short circuits. Identification can be done by examining the capacitor's top: if swollen, cracked, or stained, it is damaged. Measuring with a multimeter in capacitance or ESR mode confirms loss of capacity. Replacement should be with a capacitor having the same voltage (V) and capacitance (µF) values, preferably low ESR and rated for 105°C for better longevity. Historically, the capacitor plague from 2000 to 2007 affected millions of devices due to defective electrolyte formulations, causing premature failures.

Frequently Asked Questions

Why does an electrolytic capacitor blow?

Common causes include overvoltage (exceeding the rated voltage), reverse polarity, excessive ripple current causing overheating, natural aging with electrolyte drying out, or manufacturing defects.

How to visually identify a blown capacitor?

Look for bulging or swelling at the top, cracks or deformation of the can, signs of electrolyte leakage (dry or wet residue), and sometimes a strong fishy or chemical smell.

Can I use any capacitor as a replacement?

No. Use a capacitor with the same capacitance (µF) and a voltage rating equal or higher (never lower). Prefer low ESR models rated at 105°C for better reliability. Ensure physical size fits the board.