Re: capacitor testing question

Jan 18, 2005 4 Replies
R


I have a broken small appliance (food processor) where I think the problem


>may be with the motor start capacitors. When I try to use the unit, there
>is a buzz, but the motor doesn't run. There are 2 capacitors labeled
>"motor start". Both are rated for 170 VIC. One is 100 mF; the other is
>130 mF. All I have for testing is a digital multi-meter. When I test both
>of the capacitors on a high-resistance scale, they seem to pass current for
>about 15 seconds. (On the 200k ohm scale, the resistance slowly rises
>until it shows "open".) Does this mean that they are bad? Is there any
>other thing I can test without a capacitor meter?
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A

No, on the contrary: it's normal. You're charging the capacitor up. Current slows and finally stops as the voltage on the capacitor approaches that of your multimeter. Try measuring the voltage across the capacitor afterwards: you'll see it discharge through the meter.

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J

To know if the cap is on value, you need a capacitor testing meter, or such a scale on your volt meter. To see if the cap is functioning properly under working conditions, a capacitor ESR meter is required. The only other reliable way to test them, is to change them.

It is also possible that the motor is defective. I have seen defective motors in appliances from time to time.

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Jerry G. ======

15 seconds. (On the 200k ohm scale, the resistance slowly rises until it shows "open".) Does this mean that they are bad? Is there any other thing I can test without a capacitor meter?
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M

I doubt it. Have a better look; you should replace them (if necessary) with the correct values.

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