Construction and operating instructions Best.-Nr.: 47773 Version 2.02, Date: November 2008 ESR - Meter ESR 1 English translation This German to English translation was made in September 2018 by someone who is not in any way affiliated with ELV. This translation is mainly based on Google Translate. No copyright infringement was intended. This translation is provided as-is and without guarantee, for the benefit of hobbyists and makers. Technical support For questions and information please contact our technical staff: ELV • Technischer Kundendienst • Postfach 1000 • D - 26787 Leer Repair service For devices made from ELV kits, we offer our customers a repair service. Of course your device will be repaired as cheaply as possible. In the sense of a quick completion, repair is carried out immediately if the repair costs do not exceed half of the complete kit price. Should the defect be bigger than that, you will first receive a non-binding quotation. You are welcome to send your device to: ELV • Reparaturservice • Postfach 1000 • D - 26787 Leer ELV Elektronik AG • Postfach 1000 • D-26787 Leer Phone 04 91/600 888 • Fax 04 91/6008-244 1 Construction and operating instructions Electrolytic capacitor tester with in-circuit testing capabilities ESR Meter – ESR 1 This useful little helper facilitates debugging in modern electrical appliances, such as TVs, monitors, video recorders, etc. The meter determines the equivalent series resistance (ESR) of an electrolytic capacitor (in short: Elko) ; even in circuit, without desoldering. The ESR gives information about the state of aging or the "quality" of an electrolytic capacitor. Especially in switching power supplies, electrolytic capacitors age faster than "normal" due to the high switching frequency or high working temperatures. When capacitors are used for filtering the output of a power supply, if the ESR increases too much, the power supply may not be able to operate properly. Of course, the ESR 1 can also be used to measure ohmic resistances in the specified measuring range. its temperature being kept within the Aging capacitors specified operating range (usually, max. 85°C or 105°C), the average service life Technical data In general, most electronic components, is 1000 to 3000 operating hours. The Power supply: ..................9-V-Battery (such as semiconductors, resistors and storage itself causes a steady loss of Current draw: .............................8 mA others) have an almost unlimited life, capacity over time. Therefore, it is not Measuring range: ......0,01 to 19,99 Ω provided that they are not overloaded and recommended to use electrolytic Accuracy: ................................... ± 5% operated in their designated working capacitors that have been stored for more Miscellaneous: ......Low batt. indicator environment. However, there is one than 10 years when building your new Auto-Power-Off exception - the electrolytic capacitor (in projects. One of the main reasons for this Dimensions German: "Elko"). When an electrolytic is that the liquid electrolyte inside the (Housing): ............. 140 x 60 x 26 mm capacitor is used with capacitor dries out, thus reducing its capacity and performance. 2 As a consequence, the switching power to the capacitor results in a phase shift of Equivalent circuit supply no longer works properly. 90 ° between the voltages at "ESR" and of the capacitor Usually the device only seems to work at "C". The impedance (Z) of the flawlessly for a short time, but soon capacitor (ignoring Ls and Rp) is R p switches off or goes in standby mode. To composed of the two components avoid this problem, the manufacturers reactance (Xc) and the ESR, defined in use so-called low-ESR electrolytic the following formula: capacitors, which have an extremely low R ESR C Ls internal resistance and are designed especially for high temperatures. These Fig. 1: The AC-equivalent circuit electrolytic capacitors are usually diagram of the capacitor illustrates the recognizable by the imprint "105 ° C" - a term ESR (Equivalent Series standard electrolytic capacitor is only Resistance). suitable for temperatures up to 85 ° C. But even these low ESR types are not The formula can be graphically The operating temperature is a critical excluded from the aging process. represented using a phasor diagram that parameter in the dessication process. It However, for financial reasons, looks like this: is determined by the ambient manufacturers often use normal temperature and the heat generated by capacitors instead of low ESR ones in the circuit itself. A rule of thumb says switching power supplies, leading to ESR that a 10K increase in temperature early failures. halves the life of an electrolytic Xc capacitor. Easy ESR measurement Z If a capacitor is used for voltage stabilization in a conventional linear With the ESR measuring device power supply, a capacity reduction of presented here, the internal resistance say 4700 uF to 3300 uF is usually still (ESR) of an electrolytic capacitor in the Figure 2: The phasor diagram tolerable. circuit can be measured without having illustrates the relationship between The situation is different with to desolder it. As a result, the annoying ESR, impedance and reactance. modern switching power supplies. Here and time-consuming desoldering process the Elkos are exposed to extreme loads. is avoided, together with the subsequent If we can reduce the reactance of the Due to the relatively high switching measurement of capacity. Moreover, in capacitor to about zero, we could easily frequency and the high, partly such cases, as already stated, the ESR is resolve the formula to ESR. The variable rectangular pulsed currents, the more meaningful than the capacitance parameters for Xc are the frequency and electrolytic capacitors heat up, which measured with a capacitance meter. the capacity. The capacity is determined leads to a rapid decrease in the service by the DUT, so only the frequency life. It's no coincidence that power remains. If we set the measurement Before going on to the circuit supplies in computers are one of the frequency high enough, Xc tends to zero, description of the "ESR 1", we briefly most common causes of failure. These as the following example proves: switching power supplies are consider the theoretical basics of ESR increasingly finding their way into measurement. Each capacitor is lossy due modern consumer devices. to its design. Electrolytic capacitors are A trend can be observed: many particularly affected. For a better of these electronic devices such as TVs, illustration, Figure 1 shows the Example: f = 60 kHz, C = 100 µF VCRs, monitors, etc. already fail after a equivalent circuit diagram of a capacitor relatively short time. The cause of the operated with AC voltage. The parasitic fault is often a defective electrolytic components are characterized as follows: capacitor in the switching power supply. If you measure such electrolytic By this finding we can solve the capacitors with a capacitance meter, you RESR = Series loss resistance formula for the impedance Z to ESR, will notice with astonishment that they RP = Insulation resistance, or which looks like this: have only slightly lost their capacity. parallel loss resistance (caused by the Why did the device or switching power leakage of the dielectric) supply fail? LS = Series Inductance of the This is where the internal terminals and the electrodes resistance of the capacitor comes into With an AC resistance meter operating play, which is also called ESR at a relatively high frequency (60 kHz in (Equivalent Series Resistance). Rather, The ESR (RESR) is made of the our case), we can determine the ESR of a this resistance represents the sum of all resistances that form through the leads, capacitor. the serial losses of a capacitor. The the transition to the electrodes, and the There are basically two different internal resistance is also directly related resistance of the dielectric. This ESR measuring methods for such to the state of aging of the electrolytic can't be measured with a standard "ohmmeters": One measures with capacitor, it increases with the age of the multimeter and needs an AC constant current and the other uses a electrolytic capacitor. The effect of high measurement. In order to find a suitable constant voltage. We chose the variant ESR on power supplies is predominant measuring method, we will only focus on with a constant voltage. at high frequencies. the RESR component. Applying an AC voltage 3 LCD1 Auto-Power-Off +9V C1 R4 +5V +9V T1 100K C2 C3 T S BC4 A3 B3 C3 D3 E3 F3 G3 A2 B2 C2 D2 E2 F2 G2 A1 B1 C1 D1 E1 F1 G1 BP BP P4 P3 P2 P1 Low-Bat + 100n 2139 3 30 29 11 10 9825 24 15 14 13 21 20 19 18 17 40 28 12 16 38 BC558C 63V R5 100n 10u IC1 8 26 27 220K 31 32 22 23 63V 25V 13 Set QC11 LCD_3,5stellig R1 22K R17 A +9V 220K 12 9 Q¯ D Reset R20 22K 2M2 R11 R12 R13 100K 10 CD4013 470K 10K R18 R2 68K C8 19 23 16 24 15 18 17 22 12 11 10 9 14 13 25 5 4 3 2 8 6 7 R3 T2 220R LowBat T3 F3 F2 F1 A3 B3 E3 A2 B2 E2 A1 B1 E1 C3 D3 C2 D2 C1 D1 G3 G2 IC2 IC2 +2.5V G1 100n AB4 On/Off BC548C D1 +2.5V 63V 6 2 - BC558C IC6 R14 100K - S1 R8 ICL7106 1 500R 7 + 100K LowBat D2 R7 1N4148 + R6 C5 +2.5V A 220R + BP POL TEST VREF+ VREF- COMM IN- IN+ OSC1 OSC2 OSC3 CREF+ CREF- A/Z BUFF INT B 3 25K 5 + + R25 37 36 35 32 30 31 40 39 38 34 33 29 28 27 C6 LM385 21 20 R16 R23 BAT1 220u 1V2 T5 220K 1K 16V C7 LM393 LM393 C4 + 47K R29 220n R10 R9 R15 BC548C 100K 22K 63V 100n 100u C18 C19 C20 C21 63V 16V R30 R28 180K 330K 100K 100p 100n 220n 220n ker 63V 63V 63V +5V 470K R31