13-03-2014, 09:20 PM
"lawrence i was going to do the ohm checks you mentioned after powering up with 5 volts for ten mins will this charge the caps and ok to do the checks."
No, if you need to check for leakage in a capacitor by an ohms test the capacitor should be discharged first (power off of course) Then you need to disconnect one end of the capacitor from the circuit to get a reliable resistance reading.
The reason for discharging the capacitor is that any voltage charge that might be retained in the capacitor can be many times the voltage of the internal battery in the test meter.
If a capacitor is across a low resistance circuit the capacitor should discharge more or less straight away, if it's across a high resistance circuit then the discharge time will be longer, how much longer depends on the value of circuits resistance and the value of the capacitor that is charged up.
You also need to be aware that testing for capacitor leakage on a standard multimeter isn't by any means conclusive, in many cases the test voltage output from a meter set to measure ohms will be far less than the working voltage of the capacitor under test.
Anyway I'm digressing, the fact that nothing is getting warm indicates so far so good with your voltage test
If you need to know how a meter works and what the electrical properties of a capacitor are then click on the link below, it''s all in there somewhere, the link is worth saving:
http://www.allaboutcircuits.com/
Lawrence.
No, if you need to check for leakage in a capacitor by an ohms test the capacitor should be discharged first (power off of course) Then you need to disconnect one end of the capacitor from the circuit to get a reliable resistance reading.
The reason for discharging the capacitor is that any voltage charge that might be retained in the capacitor can be many times the voltage of the internal battery in the test meter.
If a capacitor is across a low resistance circuit the capacitor should discharge more or less straight away, if it's across a high resistance circuit then the discharge time will be longer, how much longer depends on the value of circuits resistance and the value of the capacitor that is charged up.
You also need to be aware that testing for capacitor leakage on a standard multimeter isn't by any means conclusive, in many cases the test voltage output from a meter set to measure ohms will be far less than the working voltage of the capacitor under test.
Anyway I'm digressing, the fact that nothing is getting warm indicates so far so good with your voltage test
If you need to know how a meter works and what the electrical properties of a capacitor are then click on the link below, it''s all in there somewhere, the link is worth saving:
http://www.allaboutcircuits.com/
Lawrence.
