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#1
05-22-2012, 05:20 PM
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Can I test a Capacitor with a multimeter?
I just bought some of these 150uf caps from Ebay,
and one was dented, so I decided I should probably check them before installing. I know this is probably the cheapest meter available, but I picked it up at a garage sale over the weekend for a buck. Does anyone know if I could check this electrolytic with it? Magnavox300 
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#2
05-22-2012, 06:35 PM
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Not really. You can put it on Ohms and see if the needle kicks momentarily, then measure the 1.5 Volts that may still be on the capacitor but none of this really tests much of anything.
The tests for electrolytic capacitors are capacitance, leakage, and ESR. You need more than a VOM for that.
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#3
05-23-2012, 01:03 AM
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If you want to test caps in tube era gear then I'd recommend looking for a good vintage eye type capacitor tester like this.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
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#5
05-23-2012, 06:34 AM
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Using a VOM is not a good way to test a capacitor. The Heathkit C-3 tester above is an excellent inexpensive tester when restored. It has very few capacitors and can be restored in an evening. It can accurately tell the condition of capacitors (out of circuit) quickly. One reason you can't use VOM is that you have to apply the working voltage on the capacitor under test. The VOM may apply only 1.5 volts to a capacitor that has a working voltage of over 400 volts. Low voltage will not break down a leaky capacitor.
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#6
05-23-2012, 09:20 AM
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The EICO 950 is another good tester. Mine is going on 36 years old.
Not my equipment below... http://www.ebay.com/itm/EICO-Model-9...a#ht_483wt_754 http://www.ebay.com/itm/Eico-Model-9...0#ht_500wt_920
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#9
05-23-2012, 09:15 PM
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Quote:
I am going to look for one right now! By the way, what does anyone recommend as far as a tube tester? I would love to get one of those too!! Magnavox300
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#10
05-23-2012, 09:56 PM
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An analog ohm meter can be used to check a capacitor. Notice I say check, but not test. The procedures have been in electronics training publications for decades, but what you end up with is more of a check as to whether or not the capacitor is shorted; thus it would not really be a test under loaded conditions which would be more ideal, but not everyone has the time or money to hunt vintage test equipment which may need capacitors to operate correctly; one never knows. The ohm meter test really only works for larger value capacitors as you might find in the filter section of a vintage power supply circuit, ie, 40 microfarad, 10 mfd, etc. In short you should see the meter race to full (or near) deflection (zero ohms), and then slowly fall to a very high value of resistance. If the pointer stops anywhere say mid deflection then toss the capacitor. If memory serves me correctly anything under hundreds of thousands of ohms is faulty. Someone here may elaborate on this, or if not I am sure that a Google search might result in a number of related articles. That cheap meter should do OK for now, but that condenser tester sure would be nice. I would love to have one if I could find one in known to be working condition for a reasonable price. I personally don't recommend and ESR meter. The one that I used in college never seemed to do anything more than the capacitance function of most modern digital VOMs.
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"
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