Many times you'll find a small ceramic in parallel with the 'lytic. The ceramic cap will 'fool' the ESR meter. If it reads bad with an ESR meter it is bad. If it reads good you need to remove it, let it cool off (heat improves it ) and measure it again. There's a good chance the cap is bad. In switching supplies the caps need to be perfect. There is no 'good enough'. Make sure you buy caps with lowest E$R / highest ripple current.

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