ANSWERS: 4
  • depends on the testing point... if the ring it was soldiered into is separated from the board and you are testing it down the line then that is infinite too
  • Capacitors that aren't connected to anything will always show infinite resistance *after charging up*. Small capacitors will show infinite resistance on a meter almost instantly, whereas larger value capacitors (in the microfarad range) will initially show a low resistance then it will build up to infinity. If you short the leads out and then measure again, you'll see the same "charge up" behavior. So a bad capacitor would either show fixed resistance (like 100 Ohms, say). If the capacitor is large, but measures infinity instantly, it's probably gone bad. There are better ways to measure a capacitor, though. There are meters specifically designed to test and measure their value.
  • a VOM can only give a rough test to a capacitor - what you are seeing is the ESR, but the meter is not built for that function - a electrolytic cap between 5uf and 1000uf will show some ESR but smaller caps (1uf & smaller) will show as open on a resistance scale, but they hardly ever fail
  • correct me if i'm wrong. i have this power supply, which i suspected to have a defective capacitor. when i test the capacitor, i switch ON the power supply, placed the red test pin to the positive + sign of a capacitor and the black one to the negative -. is this the correct way of testing capacitors on board?

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