29-06-2016, 08:34 AM
The usual problem with these testers is that they over read on leaky caps. Simply because they work by charging the cap and timing how long it takes to charge. A very low reading like this (essentially stray capacitance) suggests an open circuit capacitor. Of course all the caps you've tested could be o/c. Do a cross check by charging a cap from a power supply to some convenient voltage and watch it discharge slowly via a DVM. A 32uF cap and 10M DMM will have a time constant of 320 seconds. So if no leakage it would take over 5 minutes to drop to approx 30% of the voltage you charged it to. Leakage means it will discharge quite a lot quicker.
If you charge a cap beware of connecting it to a tester before it's fully discharged. Many of these cheap testers won't like it up em.
If you charge a cap beware of connecting it to a tester before it's fully discharged. Many of these cheap testers won't like it up em.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
