Help with capacitor measurement  - Page 1
Forum section: electronics / beginners

author: Tomer
author_rank: Regular Contributor
timestamp: January 31, 2018, 04:15:32 pm
content: Hi Everyone and thank you for the help.Can you help me understand how to measure the following capacitor (picture in the link)Should i measure the same as electrolytic capacitor ?Using my Fluke 117 Auto Range on Capacitance, i am getting the following result (picture in the link)Am I doing something incorrectly ? to my understanding 12nF (1000) = 12000 nF = 12 uFPlease correct me if i am wrong.https://photos.app.goo.gl/ZtylaeUVeWQTsM6q1Thank you fTom

author: helius
author_rank: Super Contributor
timestamp: January 31, 2018, 04:33:37 pm
content: The "1000" is the range. In this range the meter reports from 1 to 1000 nF.The reading is 12 nF. This is only 1% of the rated value (1uF). So this measurement does not accord with the specified rating.Film capacitors are non-polar and you should verify the measurement with the leads reversed.

author: Tommy1984
author_rank: Regular Contributor
timestamp: January 31, 2018, 04:41:19 pm
content: I agree with Helius.By the way Dave made a nice review about the Fluke 117.You can watch it!

author: Tomer
author_rank: Regular Contributor
timestamp: January 31, 2018, 06:16:12 pm
content: Thank you both for the quick replay and video!!I double checked the value, i switch the fluke test leads position and in both cases i got 12nF.Can i conclude from the measurement that i should replace this Capacitors? this is a power supply section for a sound card.I have been told that this type of Capacitors don't go bad and don't get old, and there is a good chances that my problem is elsewhere.Thank you againTom

author: The Soulman
author_rank: Super Contributor
timestamp: January 31, 2018, 06:32:40 pm
content: If it is part of the power input line filter than sure it can fail.Can you measure the the dc resistance of this cap?It should start low and eventually climb to OL.If it doesn't reach OL or reaches it very quickly it is probably safe to say it is bad.

author: Tomer
author_rank: Regular Contributor
timestamp: January 31, 2018, 06:48:15 pm
content: Thank youIs it possible to explain how to perform this measurement ?1) Should i measure while the cap is in the circuit or out of the circuit ?2) If the cap should be in the circuit, should the device be powered on ?3) What settings should I use in my Fluke (Vdc?)Tom

author: morgs
author_rank: Newbie
timestamp: February 01, 2018, 07:49:40 am
content: Measure out of circuit with meter on ohms, to measure dc resistance.

author: Tomer
author_rank: Regular Contributor
timestamp: February 01, 2018, 08:57:58 pm
content: Thanks for the info.I found the following article (link below) and followed "Method 3"I guess this is the same as explained, here on this thread ?https://www.electricaltechnology.org/2013/06/how-to-check-capacitor-with-digital.htmlUsing this test my cap automatically show"OL".ThanksTom

author: Tommy1984
author_rank: Regular Contributor
timestamp: February 01, 2018, 09:21:49 pm
content: Quote from: Tomer on January 31, 2018, 06:48:15 pmNO YOU CAN'T!Always remove or desolder the capacitor from the circuit before measuring it.One thing more, it's highly recommended to discharge the capacitor before measuring especially, if you using LCR-meter.regards,Tommy