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I am noobi in soldering and don't have much knowledge to identify components, i have a lot of Capacitors and resisters, now i want to know if i need 10U 25V Capacitor from what i have stock than how i check and select correct one, if Digital Multi Meter set to 200 Ohms range than what ohms reading it will show if i want 10U 25V? in case if i don't have 10U 25V than what will be alternate, i am trying to fix my laptop motherboard charging section so need to replace 10U 25V Capacitor, below is 10U 25V Capacitor which i need to replace from motherboard, enter image description here any help will be apprenticed, Thanks.

The 101
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  • This question is based in a misunderstanding of capacitance, and it's not even clear why you think that particular capacitor needs replacing (it most likely does not). – Chris Stratton Nov 15 '17 at 02:50
  • why you think my question is not valid? and why i think that particular capacitor needs replacing is another question which defiantly i not asked here, please read again my question, i want to know how to choose "10U 25V" SMD capacitor if it not marked, – The 101 Nov 15 '17 at 02:53
  • Your refusal to state why you think the capacitor needs replacement will quickly doom your question, as the likely error there makes the whole thing irrelevant. But even if it actually did need replacing, part selection questions are *also* off topic here. Please read the rules of this site before you violate them even more. – Chris Stratton Nov 15 '17 at 02:55
  • i not refuse to tell why i think it need to replace, but i just answer your rude reply, if you can't help than you should not comment on this question, if you have knowledge than pls tell how to check such thing, else thanks you for your time to comment, – The 101 Nov 15 '17 at 03:03
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    If you don't refuse to tell why you think the capacitor needs to be replaced, then you should actually tell us why. Don't expect us to go search through your post history to understand the context of this question, – The Photon Nov 15 '17 at 03:05
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    If you actually understood what capacitance was, you'd realize your question is nonsense. Step back and describe the actual problem, and there's a chance some practical help with that might leak through while your question is on its way to closure. – Chris Stratton Nov 15 '17 at 03:06
  • Also it's not clear if you want to test a damaged part (which is probably useless even if you have a multimeter with a capacitance function) or you have a mixed lot of potential replacement parts and you want to test those to find one with the correct capacitance. – The Photon Nov 15 '17 at 03:09
  • @The Photon i want to replace such capacitor coz those are responsible of charging sections so it need to test whether its got bad or not, since i checked my board as per schematic so need to replace this capacitor. – The 101 Nov 15 '17 at 03:19
  • @The101: I have read the comments twice. Not one of them is rude but you have taken offence at being asked for clarification. "*... if my question is pointless / nonsense / misunderstanding / violate of rules than why you bother to comment here?*" Because many of us care about the standard of the site. "*... thank you for your time and pointless discussion.*" This attitude will get you nowhere and is usually only seen in comments from new users who don't understand how the site works. The site has rules and they are enforced. Chris is right. You can't measure capacitance with an ohm-meter. – Transistor Nov 15 '17 at 04:27
  • @Transistor please read again all comments, where Chris said i can't measure capacitance with an ohm-meter, The Photon said this & i not dis-agree on it since i am noobi so trust what experienced ppls said is more valuable, my attitude is totally ok and what i asked here is a noobi normal question, but experienced ppls should be polite here but not takeover to new ppls, thanks & have a nice day, tho you guys don't want any noobi come to asked you help, – The 101 Nov 15 '17 at 05:04
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    @The101: The site has thousands of questions by new users. They are welcome here provided they abide by the site rules. "*... my attitude is totally ok ...*" OK. No point in further discussion. Bye. – Transistor Nov 15 '17 at 05:10
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    Wanting to use an ohm-meter to measure a capacitor to fix the charging circuit is like wanting to use measuring cups to figure out the size of the lug nuts on a car to change them out because the car doesn't start. There's no issue asking such a question as someone inexperienced, but insisting that the lug nuts are keeping the car from starting without any explanation as to why you think that is the case will only serve as frustration for everyone. – W5VO Nov 15 '17 at 06:43
  • VTC as unclear, downvote for the unhelpful attitude which will make this impossible to answer. – pipe Nov 15 '17 at 09:25
  • @The101 Related: https://electronics.stackexchange.com/questions/334128/how-do-i-identify-smd-components-or-any-component – Voltage Spike Nov 15 '17 at 18:11

2 Answers2

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When you test a capacitor with an ohmeter you will get a measurement. But it's very hard to correlate the ohmeter reading with the capacitance of the capacitor, so the measurement is not very useful.

What you read with the ohmeter depends on the details of the design of your multimeter (how much current or voltage it uses for its resistance measurement) and will typically depend on how long since you contacted the capacitor with the probes, and the state of charge on the capacitor when you made contact.

If you measure the capacitor without removing it from the circuit board, it will also depend on all the other components connected to the same nodes on the board.

The Photon
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A capacitors' resistance is reactive. The resistance measurement will depend on a few factors. The formula for capacitive reactance is Xc = 1/(2 pi F C). Where "Xc" is capacitive reactance (resistance), "pi" is the number pi, "F" is the frequency of the signal through the capacitor, and "C" is the measurement of the capacitor in Farads. In other words, you can't just put a multi meter on a capacitor, and measure it's ohm's. The Ohm reading of a capacitor is dependent upon the frequency going through it and it's capacitance value.

But, to answer your question, If the new capacitor that you have is marked "10U 25V" properly and the markings are correct, it should work. It should be somewhat safe to assume that the original designer used the proper component when the circuit was originally designed.

CigEmacs
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  • yes capacitors are new but there is no marking on it since they are SMD capacitors so how i know if i have "10U 25V" capacitor? how do i check this with multi-meter? – The 101 Nov 15 '17 at 02:47
  • SMD components usually have markings. You might need a magnifying glass to read them though. What makes you think that the capacitor is bad? The only way to check the value if you are unsure and there are no markings would be to create a test circuit and preferably have an oscilloscope and function generator for the greatest accuracy. – CigEmacs Nov 15 '17 at 02:52
  • Of course there is another way, get a capacitance meter and test the capacitors OUT of circuit. I was assuming that you did not have a capacitance meter earlier. I think that you are more likely to have a capacitance meter instead of a function generator and oscilloscope though. Just a guess. – CigEmacs Nov 15 '17 at 03:01
  • @CigEmacs, the devices shown in OP's picture almost certainly don't have markings. – The Photon Nov 15 '17 at 03:07
  • I was actually referring to his "New" capacitors. But what new components have you ever received that don't at least have markings on the packaging as to what exactly they are? I guess that they aren't new then? – CigEmacs Nov 15 '17 at 03:13
  • @CigEmacs they are new but mixed together with other size hence my question start, when it bought, it do have mark on its little shopper but after all other capacitors mixed, i can't figure out which one is what size, so i post question for help, – The 101 Nov 15 '17 at 03:24