Ceramics don't normally go bad but if they do I assume they go short circuit as the dielectric has been damaged. I suppose it's possible for them to go open circuit but the only way I can see it happening is if it's been mechanically damaged, i.e. the ceramic is chipped and the wires are starting to come loose.
Nigel would disagree but I've never seen any tantalums go bad but according to him they fail short circuit which makes things easy.
I would check both ceramics and tants on a multimeter with the resistance setting, they should read open circuit, then with the capcitance setting, they should be within their rated value by about 20%.
If your meter doesn't have a capacitance setting then you can make your own very basic capcitance meter with an astable multivibrator like the 555 timer.
How to chek other than Electrolytic Capacitors ?
- 5th January 2008 05:42 PM #1aljamri
How to chek other than Electrolytic Capacitors ?
Hi everybody,
As a maintenance guy, I get many discarded boards from faulty equipment. I spend sometime on removing their components, check them and sort them for future needs. Resistors, diodes, transistors, LEDs, and Electrolytic Capacitors are easy to test, but the other than Electrolytic Capacitors such as ceramic and tantalum can not be checked. Is there any way to check them?
ThanksIts what your friend in Your mind, what you in your friends mind
- 5th January 2008 05:58 PM #2Hero999 0
- 5th January 2008 05:59 PM #3ericgibbs
Super ModeratorYou could build this tester:
http://members.shaw.ca/swstuff/esrmeter.html0Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
"Nigels Asm tutorials:" www.winpicprog.co.uk/
"Ian Rogers 'C' conversion of Nigels Asm tutorials:" http://www.electro-tech-online.com/c...torials-c.html
- 5th January 2008 06:16 PM #4audioguru
I have had many tantalum capacitors "disappear". All that was remaining was their two short wires. They were 25V and 35V ones operating at regulated 15V and they blew up.
I have never had an electrolytic capacitor fail on any of my projects.
I have also never had a diode, transistor or IC fail on any of my projects for 48 years.0Uncle $crooge
- 5th January 2008 06:53 PM #5Nigel Goodwin Super ModeratorNo - not easy! - imagine a board about the size of an A4 sheet of paper, covered with components, with tantalum capacitors all over, many on the same HT rails. You know it's got a S/C tanalum on a specific rail, but there are LOT'S of them all over the board on that rail!.
Originally Posted by Hero999
But for checking them after removing them, obviously easy! - if they aren't short, they are almost certainly OK.0PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk
- 5th January 2008 06:54 PM #6felis This kind of fault happens quite frequently. Many modern (20 years or younger) ceramic leaded capacitors are simply 1206 SMT parts with leads soldered to it. The whole thing then gets covered with epoxy. When one tries to extract it, solder joint inside the cap fails from mechanical stress/overheating. Originally Posted by Hero999 0
- 5th January 2008 06:59 PM #7Speakerguy
My Fluke 177 seems very accurate at measuring capacitance. It has a range of 1nF up to a 10,000uF. It seems very accurate even at the very low end of its range. It is an expensive meter but if you do a lot of work it may be worth the expense.
0Last edited by Speakerguy; 5th January 2008 at 07:01 PM.
- 5th January 2008 07:36 PM #8audioguru Some guys use a blow torch to desolder parts. Originally Posted by felis
Other guys us a soldering iron without temperature control to desolder parts.
Same thing.
My temperature controlled Weller soldering iron never overheats anything.0Uncle $crooge
- 5th January 2008 08:09 PM #9Hero999
I've used a non-temperature controlled heat gun to desolder electrolytic capacitors before and watched them all pop like caps in a toy gun.
0
- 6th January 2008 01:09 PM #10aljamri My Fluke 179 gives me "DISC" indication for non-polirized capacitor, or there is another setting i mesed? Originally Posted by speakerguy79 0
Last edited by aljamri; 6th January 2008 at 01:13 PM.
Its what your friend in Your mind, what you in your friends mind
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