How to Identify Japanese Electrolytic Capacitors
By Gabriel Torres on July 31, 2008
Not all electrolytic capacitors are manufactured equally. Japanese and solid caps have better quality, protecting your equipment from the infamous capacitor leakage problem and also increasing the life-span of your equipment, especially if it works at high temperatures, like it is the case with power supplies. In this short tutorial we will teach you how to identify Japanese capacitors and why they have a better quality.
In order for you to understand why solid and Japanese capacitors are better, let’s explain what a capacitor is and how electrolytic caps are manufactured. By the way, solid aluminum capacitors are also electrolytic capacitors but using a different packaging.
The main goal of a capacitor is to store electric charges. The amount of electric charge it can store is given in a unit called coulomb. The capacitance of a capacitor is how much electric charge it will store for each volt applied on its leads, given in a unit called farad (F). Capacitors used in consumer electronics products are measured far below 1 farad, usually on the picofarad (pF, which equals 0.000,000,000,001 F) range for ceramic capacitors, on the nanofarad (nF, which equals 0.000,000,001 F) for polyester capacitors and on the microfarad (µF, which equals 0.000,001 F) for electrolytic capacitors.
Capacitors are manufactured putting two metallic foils parallel to each other, with a material – called dielectric – between them. Depending on the dielectric material the capacitor can store more or less electric charges, and the material used gives the name of the type of capacitor. As you can see on the previous paragraph, electrolytic capacitors can store more electric charges than polyester capacitors, which in turn can store more electric charges than ceramic capacitors. Keep in mind that a capacitor that can store more electric charges isn’t better than a capacitor that can store less electric charges. Each capacitance has a different application.
Electrolytic capacitors are made with two aluminum foils placed parallel to each other, with an absorbent material wet in an electrolyte (i.e., liquid material) placed between them – hence the name of this kind of capacitor. Then this “sandwich” is spiraled.
The whole problem of electrolytic capacitors is that the electrolyte tends to dry out, degrading the capacitor (i.e., making it to lose its storage capacity), causing a mal-function on the circuit where it is installed. For example, one of the most popular uses for electrolytic capacitors is on filtering circuits and if the capacitor has gone bad the filtering simply won’t happen, which will cause a malfunction on the circuit after the filtering stage. A PC power supply with bad a filtering stage would deliver voltages with a huge fluctuation, causing malfunction or even burning your motherboard, hard disk drive, etc.
As you can imagine, the liquid inside the capacitor will only dry out if the capacitor isn’t perfectly sealed and/or if the capacitor is exposed to high temperatures (the definition of “high temperature” for us is any temperature above the standard room temperature of 25° C or 77° F).
But this is not the only problem that can occur. If the capacitor isn’t perfectly sealed the liquid inside the cap can leak, and it can even corrode the printed circuit board where the capacitor is installed.
Also the electrolyte inside the capacitor can vaporize under high temperature (or if a voltage higher than the maximum allowed is applied), creating a pressure on the capacitor case, making the capacitor to swell or even explode.
All capacitors have temperature and voltage markings. Temperature is usually rated at 85° C (185° F) or 105° C (221° F). These numbers should be far above the actual figures that will be used, the higher the better. If these numbers are exceeded, the above problems can occur. But of course under normal usage of a circuit this won’t occur, unless someone placed a capacitor with wrong specs by mistake in the circuit.
The two main problems with electrolytic capacitors are the use of a bad sealing and the use of a bad electrolyte. A bad sealing will make the electrolyte to leak or evaporate. And a bad electrolyte can do lots of stuff, the most common ones being vaporizing at a temperature lower than the temperature printed on the capacitor label (making the cap to swell or to explode) and corroding a cheap sealing material and leaking.
Japanese capacitors are notoriously known by their above-the-average quality (good electrolyte and good sealing), while Chinese capacitors have the bad reputation of using cheap electrolyte and cheap sealing, what can lead to the problems we explained. Solid capacitors are also immune to the above problems as they provide the best possible sealing.Identifying solid capacitors is easy, as they have a complete different physical aspect (see Figure 1). But how can you tell whether a given electrolytic capacitor is Japanese or not?
The main problem is that capacitors don’t carry a “Made in” or similar phrase printed on their bodies. This makes the whole process of discovery the country of origin very hard. Several manufacturers won’t even print their names, only their logos. Sometimes not even that! Some logos have the name of manufacturer on it (e.g., Sanyo), but in most cases they haven’t (see real example in Figure 2)! Some manufacturers will only print the capacitor series, and you will have to be smart enough to know that the number printed is a series and you will have to find the manufacturer by yourself!
If you are able to decode the manufacturer logo or to know which company carries a particular capacitor series, you will be able to find out the country of origin, by knowing where in the world that particular manufacturer is based. Sounds complicated? It is. For most people it is an unsolvable detective work.
But don’t worry. Our goal with this tutorial is to provide you with a table containing the most common Japanese manufacturers and how to identify their capacitors. Of course there are more Japanese manufacturers around, but we are listing only the ones typically found on PC hardware parts, especially power supplies and motherboards, which are the two components where people are more concerned about the quality of electrolytic capacitors. We are also going to publish tables with the most common Taiwanese and Chinese capacitors in order to avoid questions like “hey, I have a capacitor with XXX marking, it isn’t in your list, is it Japanese?.”
We compiled below a short table listing the most common Japanese electrolytic capacitor manufacturers that you will find on motherboard and power supplies. We also included their typical markings (as some of them don’t print their names on the capacitors) and also pictures with examples of Japanese capacitors from these brands. There is one important exception. Even though Toshin Kogyo is a Japanese company, they sell rebranded Taiwanese capacitors, from OST.
Empty Rectangle (See Figure 3)
KZE, KZJ, KZG
Logo shown in Figure 2
If a capacitor isn’t in the list provided in the previous page this probably mean that it is either Taiwanese or Chinese. Below we compiled a short list of electrolytic capacitor manufacturers most commonly found on motherboards and power supplies. This list is far from being a complete list, and you can help us out by listing other capacitor brands commonly found on PC hardware parts on the comments section from this tutorial, with the company website URL, if possible. We will try to update this list as often as we can.
|NXC, logo shown in Figure 8||SamYoung||South Korea|
|TK||Toshin Kogyo||Taiwan (rebranded OST)|
Figure 8: Samyoung logo