{"product_id":"mesr-100-esr-capacitor-meter-in-circuit-internal-resistance-tester","title":"MESR-100 ESR Capacitor Meter – In-Circuit Resistance Tester","description":"\n\u003ch2\u003eMESR-100 Professional ESR \u0026amp; Low Ohm Capacitor Meter\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eMESR-100\u003c\/strong\u003e is a precision auto-ranging capacitor ESR (Equivalent Series Resistance) and low-ohm meter designed for electronics technicians, hobbyists, and repair professionals. Using a true \u003cstrong\u003e100 kHz sine wave measurement method\u003c\/strong\u003e — identical to capacitor manufacturer testing standards — this compact tester lets you accurately evaluate capacitor condition \u003cstrong\u003ewhile components remain in-circuit\u003c\/strong\u003e, saving you hours of desoldering work.\u003c\/p\u003e\n\n\u003cp\u003eWhether you're servicing TVs, LCD monitors, audio amplifiers, or other circuit boards, the MESR-100 tells you instantly whether a capacitor is good or degraded — without removing it from the board.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eMade in Mainland China.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003ch3\u003eWhy ESR Testing Matters\u003c\/h3\u003e\n\u003cp\u003eA capacitor can test at its correct capacitance value yet still be faulty — a high internal series resistance (ESR) is the real culprit in most capacitor failures. The MESR-100 targets exactly this: it applies less than 15 mV DC (peak-to-peak) across the component, keeping voltage low enough for safe in-circuit measurement while still delivering a highly accurate ESR reading.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAuto-Ranging:\u003c\/strong\u003e Automatically selects the best measurement range from 0.001 Ω to 100.0 Ω — no manual range switching needed.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTrue 100 kHz Sine Wave:\u003c\/strong\u003e Cancels capacitive reactance so you measure only the true series resistance value.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIn-Circuit Testing:\u003c\/strong\u003e Apply less than 15 mV peak-to-peak — safe for components still mounted on the board.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e4-Digit LCD Display:\u003c\/strong\u003e High-resolution 0.001 Ω readout at the 1 Ω range for precise results.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDual Test Clips Included:\u003c\/strong\u003e Spring-loaded clips for fast, hands-free component contact.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBuilt-In Reference Table:\u003c\/strong\u003e Printed ESR chart on the meter body for instant pass\/fail comparison.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDual Power Options:\u003c\/strong\u003e 5V Micro-USB or 2 × AA batteries (not included) for bench or field use.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLong Battery Life:\u003c\/strong\u003e Over 80 hours on a set of AA batteries.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact \u0026amp; Lightweight:\u003c\/strong\u003e Just 139.6 g — easy to handle during board-level diagnostics.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eMeasurement Ranges \u0026amp; Accuracy\u003c\/h3\u003e\n\u003ctable style=\"border-collapse:collapse;width:100%;\"\u003e\n  \u003cthead\u003e\n    \u003ctr style=\"background:#f2f2f2;\"\u003e\n      \u003cth style=\"border:1px solid #ddd;padding:8px;\"\u003eRange\u003c\/th\u003e\n      \u003cth style=\"border:1px solid #ddd;padding:8px;\"\u003eAccuracy\u003c\/th\u003e\n      \u003cth style=\"border:1px solid #ddd;padding:8px;\"\u003eRefresh Time\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e0.000 – 1.000 Ω\u003c\/td\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e1% + 2 Digit\u003c\/td\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e~0.4 s\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e1.000 – 10.00 Ω\u003c\/td\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e1% + 1 Digit\u003c\/td\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e~0.4 s\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e10.00 – 100.0 Ω\u003c\/td\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e2% + 1 Digit\u003c\/td\u003e\n      \u003ctd style=\"border:1px solid #ddd;padding:8px;\"\u003e~0.4 s\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cem\u003eAuto mode: 0–2 seconds (longer for higher capacitance values). Accuracy verified after zeroing with 1 Ω, 10 Ω, and 100 Ω reference resistors.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003eFull Specifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Black\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMeasurement Range:\u003c\/strong\u003e 0.001 Ω – 100.0 Ω (ESR \/ Internal Resistance)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMinimum Capacitance:\u003c\/strong\u003e \u0026gt;1 µF\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eResolution:\u003c\/strong\u003e 4 digits \/ 0.001 Ω at 1 Ω range\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTest Frequency:\u003c\/strong\u003e 100 kHz sine wave\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTest Voltage:\u003c\/strong\u003e \u0026lt;15 mV DC peak-to-peak\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePower:\u003c\/strong\u003e 5V Micro-USB OR 2 × AA 1.5V batteries (not included)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOperating Current:\u003c\/strong\u003e 0.02 A\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBattery Life:\u003c\/strong\u003e \u0026gt;80 hours\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eItem Dimensions:\u003c\/strong\u003e 14.5 × 8 × 3 cm (5.7 × 3.1 × 1.2 in)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eItem Weight:\u003c\/strong\u003e ~139.6 g (4.9 oz)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePackage Dimensions:\u003c\/strong\u003e 17 × 9 × 5 cm (6.7 × 3.5 × 2.0 in)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePackage Weight:\u003c\/strong\u003e ~218 g (7.7 oz)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1 × MESR-100 Capacitor ESR Meter\u003c\/li\u003e\n  \u003cli\u003e2 × Test Clips\u003c\/li\u003e\n  \u003cli\u003e1 × User Manual\u003c\/li\u003e\n  \u003cli\u003e\u003cem\u003eBatteries and USB cable not included\u003c\/em\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRelated Products You May Also Need\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/screw-extractor-drill-bit-set-carbon-steel-double-sided\"\u003eScrew Extractor Drill Bit Set 5 \u0026amp; 6 Pc – Carbon Steel\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/silicone-cable-ties-reusable-cord-organizers-10-pack\"\u003e10-Pack Silicone Cable Ties – Reusable Cord Organizers\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/adjustable-label-roll-holder-3d-printed-thermal-printer-stand\"\u003eAdjustable Label Roll Holder – 3D Printed Thermal Printer Stand\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eLearn more: \u003ca href=\"https:\/\/www.osha.gov\/personal-protective-equipment\" target=\"_blank\" rel=\"noopener\"\u003eOSHA on personal protective equipment\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: What exactly does the MESR-100 measure — capacitance or ESR?\u003c\/h4\u003e\n\u003cp\u003eA: The MESR-100 measures \u003cstrong\u003eESR (Equivalent Series Resistance)\u003c\/strong\u003e — the internal series resistance of a capacitor — not its capacitance value. A capacitor can have the correct capacitance yet still fail due to elevated ESR, making this meter an essential tool for diagnosing faulty capacitors in circuit boards.\u003c\/p\u003e\n\n\u003ch4\u003eQ: Can I test capacitors while they are still soldered onto the circuit board?\u003c\/h4\u003e\n\u003cp\u003eA: Yes. The MESR-100 applies less than 15 mV DC peak-to-peak during testing, which is low enough to safely perform \u003cstrong\u003ein-circuit measurements\u003c\/strong\u003e on most capacitors without desoldering them. Always ensure the board is fully powered off and discharged before testing.\u003c\/p\u003e\n\n\u003ch4\u003eQ: What power sources does the MESR-100 support?\u003c\/h4\u003e\n\u003cp\u003eA: The meter supports two power options: \u003cstrong\u003e2 × AA 1.5V batteries\u003c\/strong\u003e (not included, providing over 80 hours of use) or a \u003cstrong\u003e5V Micro-USB\u003c\/strong\u003e connection for continuous bench use. This makes it flexible for both workshop and field repair scenarios.\u003c\/p\u003e\n\n\u003ch4\u003eQ: What is the minimum capacitor size I can test with this meter?\u003c\/h4\u003e\n\u003cp\u003eA: The MESR-100 is designed to test capacitors with a capacitance value greater than \u003cstrong\u003e1 µF\u003c\/strong\u003e. Very small capacitors (below 1 µF) may not provide reliable ESR readings with this instrument.\u003c\/p\u003e\n\n\u003ch4\u003eQ: How accurate is the MESR-100 and how do I ensure best results?\u003c\/h4\u003e\n\u003cp\u003eA: Accuracy reaches up to \u003cstrong\u003e1%\u003c\/strong\u003e in the lower ranges after proper zeroing. Before use, always zero the meter with the test clips shorted together, then verify with known 1 Ω, 10 Ω, and 100 Ω reference resistors. The built-in printed ESR reference table on the unit body helps you quickly determine whether a measured value is within an acceptable range for a given capacitor type.\u003c\/p\u003e\n\u003c!-- production-packaging-notice --\u003e\n\u003ch3\u003eProduction \u0026amp; Packaging Notice\u003c\/h3\u003e\n\u003cp\u003eTo maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"What exactly does the MESR-100 measure — capacitance or ESR?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The MESR-100 measures ESR (Equivalent Series Resistance) — the internal series resistance of a capacitor — not its capacitance value. A capacitor can have the correct capacitance yet still fail due to elevated ESR, making this meter an essential tool for diagnosing faulty capacitors in circuit boards.\"}}, {\"@type\": \"Question\", \"name\": \"Can I test capacitors while they are still soldered onto the circuit board?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. The MESR-100 applies less than 15 mV DC peak-to-peak during testing, which is low enough to safely perform in-circuit measurements on most capacitors without desoldering them. Always ensure the board is fully powered off and discharged before testing.\"}}, {\"@type\": \"Question\", \"name\": \"What power sources does the MESR-100 support?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The meter supports two power options: 2 × AA 1.5V batteries (not included, providing over 80 hours of use) or a 5V Micro-USB connection for continuous bench use. This makes it flexible for both workshop and field repair scenarios.\"}}, {\"@type\": \"Question\", \"name\": \"What is the minimum capacitor size I can test with this meter?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The MESR-100 is designed to test capacitors with a capacitance value greater than 1 µF. Very small capacitors (below 1 µF) may not provide reliable ESR readings with this instrument.\"}}, {\"@type\": \"Question\", \"name\": \"How accurate is the MESR-100 and how do I ensure best results?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Accuracy reaches up to 1% in the lower ranges after proper zeroing. Before use, always zero the meter with the test clips shorted together, then verify with known 1 Ω, 10 Ω, and 100 Ω reference resistors. The built-in printed ESR reference table on the unit body helps you quickly determine whether a measured value is within an acceptable range for a given capacitor type.\"}}]}\u003c\/script\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"BreadcrumbList\", \"itemListElement\": [{\"@type\": \"ListItem\", \"position\": 1, \"name\": \"Home\", \"item\": \"https:\/\/80721r-dv.myshopify.com\/\"}, {\"@type\": \"ListItem\", \"position\": 2, \"name\": \"Home page\", \"item\": \"https:\/\/80721r-dv.myshopify.com\/collections\/frontpage\"}, {\"@type\": \"ListItem\", \"position\": 3, \"name\": \"MESR-100 ESR Capacitor Meter – In-Circuit Resistance Tester\", \"item\": \"https:\/\/80721r-dv.myshopify.com\/products\/mesr-100-esr-capacitor-meter-in-circuit-internal-resistance-tester\"}]}\u003c\/script\u003e","brand":"SPOT","offers":[{"title":"MESR-100","offer_id":67644545040634,"sku":"14:200006151#MESR-100","price":297.7,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0867\/1415\/5258\/files\/Sa7b50b3bbf9f41bdb3058265ef4adaf2k_fb261165-d349-4808-8f08-99c85f6912f1.webp?v=1791217331","url":"https:\/\/spotmartusa.com\/products\/mesr-100-esr-capacitor-meter-in-circuit-internal-resistance-tester","provider":"SPOT","version":"1.0","type":"link"}