SDG #010 Peak Atlas ESR Meter - Review, Teardown and Analysis

The Peak Atlas ESR70 (sold in earlier guises as the ESR60 and ESR+) is a single-purpose instrument, and that focus is the whole argument for owning one. Rather than trying to be a general LCR bridge, it measures equivalent series resistance at a frequency and current that reflect how an electrolytic capacitor behaves in a real switching supply, which is exactly where high ESR causes ripple, heat and eventual failure.

This review covers what ESR is and why a capacitor that reads perfectly fine for capacitance can still be the fault in a dead power supply. Because the ESR70 injects a low test voltage, in-circuit testing is practical without unsoldering parts or worrying about turning on nearby semiconductor junctions, and the meter also handles discharge of residual charge rather than being damaged by it. Resolution at the low end matters more than headline accuracy here, since the interesting difference is usually between a few milliohms and a couple of ohms.

The teardown looks at how Peak achieves that performance: the microcontroller-driven measurement front end, the current source arrangement, and the general standard of construction behind the familiar Peak enclosure and gold-plated test clips. There is also a useful side demonstration of confirming capacitance independently using a Rigol 1000 series oscilloscope and RC time constant maths, which is a good sanity check if you want to trust a new meter before relying on it.

For anyone repairing switch mode supplies, monitors or audio gear, the takeaway is that an ESR meter finds faults a standard multimeter or cheap component tester will miss, and the ESR70 makes that a fast, one-handed job at the bench.