FAQ

ESR is the abbreviation for "Equivalent Series Resistance", sometimes referred to as "Effective Series Resistance". ESR is a DYNAMIC (AC) property of a capacitor and cannot be measured with a DC ohm meter. ESR can be considered to be the total series NON-REACTIVE AC resistance of a capacitor. ESR includes the DC resistance of the leads, DC resistance of the connections to the dielectric, capacitor plate resistance, and the IN-PHASE AC resistance of the dielectric material. The combination of components that make up ESR are symbolized by a resistor in series with a capacitor as shown. The series resistor in the symbolic representation of "ESR" does not exist as a physical entity. Direct measurements across the ESR resistor are not possible! The Capacitor Wizard® overcomes this limitation by measuring only the NON-REACTIVE AC resistance(ESR).

A property of a component is static and exists at all times. A phenomenon in Physics is an observable event that appears only in the presence of the observer under certain conditions. Since the representative ESR resistor doesn't really exist could ESR be considered a phenomenon? Just something to think about when you have nothing else to do! We will refer to ESR as a capacitor property.

An increase in ESR is frequently the first indicator of a bad capacitor. As a capacitor fails, it's chemistry changes and ESR increases until ESR reaches infinity, total failure. By measuring ESR one can locate failing capacitors before they quit completely. Often a capacitor will measure GOOD with a capacitance reading meter yet it will actually be BAD due to increased ESR! Todays' modern circuits are designed with low ESR parts. Checking ESR with the Capacitor Wizard® guarantees a reliable test of a capacitor's health.

Every repair shop has run across this problem: Caps that are known to be bad yet present correct capacitance! These are likely defective due to high ESR. Capacitance meters can not read ESR. They only measure capacitance. Capacitance is important but it is not the only important capacitor property. ESR is probably more important. A BAD capacitor can have the correct capacitance yet have HIGH ESR due to dielectric chemistry changes. High ESR upsets time constants, causes part heating, disrupts current flow. Increased ESR frequently causes complete circuit failure, even when a capacitor measures correct capacitance. Without the ESR test you may accidentally declare a BAD capacitor GOOD. A mistake like that can add hours of troubleshooting time to what would otherwise be a simple repair. Don't be fooled by a standard capacitance meter!! A capacitor's test is not complete until you check for low ESR! Use the Capacitor Wizard® In-Circuit ESR Meter for best results.

There are four EXTERNAL parallel parts you might think would interfere with in-circuit ESR measurements: inductors, resistors, solid state junctions, parallel capacitors. Except for parallel capacitors, the others do not interfer with Capacitor Wizard® in circuit ESR testing and here is why:

• Parallel inductance: The relatively high inductive reactance (XL) at 100kHz of parallel inductors you are likely to encounter has little effect on the ESR meter readings and can be ignored.
• Parallel Resistors: Resistors normally found around capacitors 1uf and up will usually be large values compared to the Capacitor Wizard®'s low input impedance (2.5ohm). Parallel resistors have little effect on the reading and can be ignored. Of course if you strap a 1 ohm resistor in parallel with a capacitor it will effect the reading. But when have you ever came across that condition in a real circuit? Never.
• Solid State Junctions: The test voltage is less than 20 mv pp, much, much too low to turn on any GOOD solid state device. (You can use the Capacitor Wizard® to find leaky or shorted diodes and transistors IN-CIRCUIT!)
• Parallel Capacitors: Occasionally will you encounter a circuit design using parallel capacitors. The ESR of parallel capacitors will measure lower than the capacitor with the lowest ESR just like ohms law. One leg of a parallel cap must be lifted for accurate ESR measurement. Both caps can then be individually tested. Why do engineers parallel capacitors? Mostly economic reasons. It is cheaper to parallel 2 cheap capacitors to lower the esr than it is to buy one low esr capacitor.

The input resistance of the Capacitor Wizard® is held very low by two one-ohm resistors (R51 & R52). If you would measure DC resistance between the Capacitor Wizard® probes you would measure 2.5ohms which includes the series resistance of the 1 ohm resistors and the DC resistance of the probe wire. This low impedance insures a proper ESR measurement discarding transients. If you attempt to test a charged cap these resistors will often just discharge the capacitor, no damage done. However if the unit under test is turned on or if the capacitor has a lot of stored energy you will damage one or both of these resistors. You may also damage other discrete parts. ALL PARTS NEEDED TO RECOVER FROM DAMAGE DUE TO A CHARGED CAP ARE INCLUDED IN OUR INEXPENSIVE Repair Kit. To avoid this damage entirely order the optional patented CapSVR ultimate protection device.

Often no damage is done. If you do damage the meter never fear, we have an inexpensive Repair Kit. Just replace all parts in the kit and you will be back in operation in no time. If you want to try to troubleshoot it yourself download my repair procedure. We sell an optional protection circuit, the patented CapSVR. It provides the ultimate protection on your investment. If all else fails you can send the Capacitor Wizard® to us for repair. We charge a low flat rate for most repairs.

Measure some low value resistors (1ohm, 2ohm 3ohm etc). Verify agreement with the Capacitor Wizard®. If the Capacitor Wizard® closely agrees then it is working properly and in calibration. This test will work for any ESR meter. Use non-inductive resistors (not wire wound)

Yes, we have an add-on optional protection kit, the patented CapSVR. We have sold the Capacitor Wizard® for over 20 years and protection has not been an issue. Most technicians know to discharge caps before testing. The Capacitor Wizard® will absorb a pretty good hit without protection. The patented CapSVR provides the ultimate protection.

Speed and accuracy. Analog meter displays are more expensive than digital displays. Here is why we feel analog displays are worth the extra expense. Human minds have the ability see and interpret meter needle movement very quickly and accurately, almost without thinking. It is a human survival instinct from eons ago. But the mind has difficulty quickly matching digital numbers to GOOD BAD or COMPARE ESR magnitudes. Using a digital display the brain must THINK and that takes time. Many need to refer to a chart. Comparing to charts always presents a chance for error.

When you understand how the Capacitor Wizard® works, you will discover other uses for it.

1. Test voltage is 20mvPP maximum. The low test voltage of 20mvPP will not turn on any solid state junctions. This means you can check solid state devices for leakage and shorts! Place the probes across diodes, transistors, triacs, IC contacts, etc. Any readings less than 30 ohms make the part suspect. Lift one leg to confirm.
2. Test frequency is 100kHz. The Capacitor Wizard® will measure inductive reactance (XL) in the very narrow range of 0.3uh to 50uh. There is a chart in the operating manual relating measured inductive reactance (XL) at 100kHZ to inductance. Why is this useful? Our customers found that video tape heads could be tested for good/bad based on the Capacitor Wizard®'s readings. It turns out that good video tape heads had inductance within the range of the Capacitor Wizard®. Readings for bad video tape heads were magnitudes different than those of a good tape head.
   
   Here is another use. Pinball game repair. Pinball games have a number of solenoids used to operate the mechanical animation and flipper movement. Each solenoid on the machine has a damping diode in parallel with the coil. How can you check the diode without cutting it loose? A regular ohm meter is useless because it will measure the low coil resistance. Since the coils have large inductances they are ignored by the Capacitor Wizard®. The Capacitor Wizard® is the correct instrument to diagnose solenoid trouble. A good solenoid/diode array will measure infinity on the Capacitor Wizard®. Any reading less than infinity indicates a problem with that solenoid/diode. Most likely a LEAKY or shorted diode. Rarely a shorted coil. Of course the same logic applies to any device that uses coils, transformers and parallel diodes.
3. Measures ESR of 1uf and up. But what happens if you measure a capacitor less than 1uf? You will read capacitive reactance (XC). For example a 0.1uf capacitor has 15 ohms capacitive reactance at 100kHz. 15 ohms is what the Capacitor Wizard® will read when you measure a 0.1uf cap. So how can this be helpful? A company in Mexico that built wiring harnesses for cars, TRW, wanted to prove a small capacitor was present in a cable bundle made for automobiles. I suggested they measure for capacitive reactance with a Capacitor Wizard®. The part was a 0.1uf cap so capacitive reactance (15 ohms) was in the range of the meter. When they measure for capacitive reactance on the cable bundle there would be three possibilities. 1) Open circuit. Part is missing 2) Correct capacitive reactance of 15 ohms. Part is present and correct value. 3) 0 Ohms. Cable or part is shorted. I sold them 2 Capacitor Wizard®'s. After compensating for stray inductance they built them into their test fixtures. TRW was very happy with my solution.

Based on this information what other clever uses can you find for the Capacitor Wizard®?