Sorry but there is no easy test. You can apply an ohm meter to it and if that shows a short the cap. is dead. When analogue meters were common it was possible to see a swing on the meter but that won't work on digital meters and wasn't definitive anyway.
Without test equipment I cannot think of a way other than substitution of the capacitor.
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
Thanks Mike. I have both analogue and digital multimeters. I've always wondered if they could be tested. My gut feeling is it's dead and I have been right on these previously so I will go with gut again.
It's for pumping from a water tank for irrigation. No, I have not looked at it yet. I have replaced capacitors in previous pumps to resolve the problem but this time, I thought I would ask others if a capacitor could be tested or not rather than using my gut feeling for the problem.
A multimeter with a capacitor setting will give you a reading to check against the capacitor size, if you know that, otherwise no good way to check it for sure. Could be 1 or 2 capacitors there depending on the motor. If you can see what the cooling fan blade does when you turn it on, does it vibtrate?
It won't start so I don't know if it vibrates. It looks like the general consensus is that it is difficult, if not impossible to test a capacitor so I will do what I have done in the past and replace it and see what happens next. The worst I am up for is a wasted capacitor, otherwise it's off to the pump electrician. Thanks all for the responses.
Capacitors are not hard to test Kevin but you must have the correct test equipment.
What *may* work is:
Connect a 12V (or higher) LED lamp between one terminal (either) of the capacitor and a 12V battery 0V (ensure LED polarity is correct)
Connect a wire (if necessary) to the other terminal of the capacitor and then "flash" it across the battery +12V terminal, repeat this "flashing" process, say, a dozen times over about five seconds or less. NB. Do not simply hold the wire on the battery post.
If the LED flickers the capacitor is *probably* good - you may need a dimly lit room to see the LED illuminate.
If there is no sign of life from the LED the capacitor is *probably* dead.
You could also listen on an AM radio to a quiet part of the AM band and if you hear a click when you "flash" the wire on the battery wire this also indicates the capacitor is probably good.
This is a poor man's signal generator.
Might be easier just to buy a new cap? :)
__________________
"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
Capacitors are not hard to test Kevin but you must have the correct test equipment.
What *may* work is:
Connect a 12V (or higher) LED lamp between one terminal (either) of the capacitor and a 12V battery 0V (ensure LED polarity is correct)
Connect a wire (if necessary) to the other terminal of the capacitor and then "flash" it across the battery +12V terminal, repeat this "flashing" process, say, a dozen times over about five seconds or less. NB. Do not simply hold the wire on the battery post.
If the LED flickers the capacitor is *probably* good - you may need a dimly lit room to see the LED illuminate.
If there is no sign of life from the LED the capacitor is *probably* dead.
You could also listen on an AM radio to a quiet part of the AM band and if you hear a click when you "flash" the wire on the battery wire this also indicates the capacitor is probably good.
This is a poor man's signal generator.
Might be easier just to buy a new cap? :)
Thanks Mike, I'll give that a go when I get a moment. Sounds like a fun experiment. BTW, I made your aerial extender a couple of days ago in preparation for our next trip in a fortnight's time. I'll let you know how it goes when we get back.
Hi all; Coming from a electronics background, there are capacitor meters that can test if the capacitor is OK or a dud. The better cap meters will also read the ESR ( electronic series resistance ) and with a faulty capacitor this is more important than the value of the capacitor, the lower esr the better. My bet is with electric start caps is to just replace it with the same voltage and capacitance ratings, but make certain the power has been switched off to the motor first !!
BTW, I made your aerial extender a couple of days ago in preparation for our next trip in a fortnight's time. I'll let you know how it goes when we get back.
Please do, I'll be most interested. As usual with RF, things can be a bit fickle, generally it works well but in some locations it doesn't make a lot of difference however it usually at least make barely readable stations readable.
If anyone wishes to buy a capacitance (and inductance) meter these are very good:
To check the capacitor safely, first check it with an ohm meter for not being short circuited and then charge it with 12VDC by connecting it to a car battery. Disconnect it and then measure the voltage with a digital voltmeter. If it measures 12V it's good, if zero it's a dud.
