We would like to introduce our new instrument for electrolytic capacitor diagnostics.

Failures of electrolytic capacitors are a major cause of defects in commercial electronic equipment. Detecting such failures is a rather difficult problem. There are several types of instruments that detect electrolytic capacitor failures. All of these instruments are based on the principle of quality-testing the electrolytic material by applying alternating current with frequencies in the 20 kHz–100 kHz range. However, all known instruments have the following disadvantages:

· Instruments in current use are implemented as multimeters with analog displays and long cables. During testing, the operator is able to track either the capacitor or the display but not both simultaneously. Under these conditions, it is very easy to lose contact between the instrument tips and the circuit board of the equipment to be repaired. Therefore, instruments in current use are inconvenient.

· All known instruments are supplied with a battery, which discharges very quickly.

· All known instruments for testing electrolytic capacitors cannot detect internal short circuits.

We have developed an instrument designed to detect all kinds of electrolytic capacitor failures (including internal short circuits) without removing the capacitors from the circuit boards of the equipment to be repaired. Our instrument’s display is in the operator’s field of vision during testing, making it much more convenient to use than current instruments. Our instrument indicates:

· electrolytic capacitors with zero capacitance (disconnection);

· bad electrolytic capacitors;

· electrolytic capacitors of average quality;

· good electrolytic capacitors;

· internal short circuits in a tested electrolytic capacitor.

The display for our instrument is very simple and is implemented with a two-color LED with red and green illumination. The display indicates the following states of the tested electrolytic capacitors:

LED color Electrolytic capacitor quality

No illumination Internal disconnection in the capacitor

Green Good capacitor

Red Bad capacitor

Red + green = orange Average quality capacitor

One of the main advantages of our instrument is that it emits a sustained beep in case of an internal short circuit in the capacitor.

We have developed three types of power supply for our instrument:

· 9 V DC internal battery;

· Commercially available external AC adapter, connected to wall outlet;

· Rechargeable internal battery.

The instrument is automatically protected from a reversed-polarity power supply connection.

If the battery voltage is low (7.6 V) an indicator LED lights up.

We are confident that our instrument simplifies detection of damaged electrolytic capacitors in electronic equipment, thereby reducing repair time.

All materials used in constructing our instrument are widely available commercial components. The instrument is easy to assemble.

We are currently developing features to improve our instrument still further.

Boris Lipkin & Boris Shtarker

Electronic Engineers

Jerusalem, Israel

E-mail: c/o Jonathan Gruenhut
jabba ~at~ bantha ~dot~ org