How do you know if an electrolytic capacitor is failing?

There are two visible signs indicating an electrolytic capacitor is failing. These are bulging of the capacitor itself and leakage of the electrolyte. Since, this forum is frequented by people who work as repair technicians, it would be interesting to read about their experiences and whether there are other less obvious signs of electrolytic death.

How do you identify an aluminum electrolytic capacitor?

The manufacturers of aluminum electrolytics offer a myriad of different types, most identified by a 2 or 3 letter code. This is usually printed on the side of the capacitor body, along with the logo of the manufacturer. As an example, I've pulled the capacitor below from my "stock" to identify and look up.

How do I know if my filter capacitor is healthy?

You need to know what's expected of the capacitor to interpret your measurements and decide if the cap is sufficiently healthy or needs to be replaced. Filter capacitors in mains operated power supplies, usually 50 or 60 Hz, will tend towards large values, usually 1000 uF or more per ampere of output current.

How do you know if an electrolytic capacitor is brown?

Aluminum electrolytic capacitors use a brown paper separator, so an old capacitor that has vented or had a seal failure may yield a brown deposit. If the deposit has a slightly crystalline appearance or is at least somewhat soluble in water, it's electrolyte.

Why do electrolytic capacitors fail?

High operating temperature is one reason that electrolytic capacitors are one of the most commonly failing components in electronics. Figure 4 shows how an electrolytic capacitor is constructed. Figure 4 – Electrolytic Capacitor Construction *If you are benefiting from The Tech Circuit, please consider donating HERE *

Can you use aluminum electrolytic capacitors in a circuit?

Fortunately good designers don't use aluminum electrolytics in sensitive locations, and paper/oil caps are uncommon these days. You'll almost invariably have to remove capacitors from the circuit to test for leakage because you don't want to expose the rest of the circuit to the voltages involved.