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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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LC meter operation
I recently bought a Sencore LC102 off of e-bay. It was calibrated just
prior to sale. When checking caps for ESR, I only get readings on electrolytics, no other type caps. Other caps cause the meter to flash a high value, regardless of control/voltage settings. The meter will read value though for all caps. Am I doing something wrong, or is my meter gimped? Thanks. |
#2
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A long shot, but ...
Is it possible that your meter actually reads out the equivalent parallel resistance of the cap (yes, I know what ESR stands for)? For most caps (but not electrolytics) this would be a very high resistance - many megohms. Just a thought. By the way, if you didn't get a manual, you can buy the instructional video on eBay for $10. Bill wrote: I recently bought a Sencore LC102 off of e-bay. It was calibrated just prior to sale. When checking caps for ESR, I only get readings on electrolytics, no other type caps. Other caps cause the meter to flash a high value, regardless of control/voltage settings. The meter will read value though for all caps. Am I doing something wrong, or is my meter gimped? Thanks. |
#3
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My guess would be that you're measuring small uF caps and the measuring
frequency is such that the series impedance (due to the uF value) is too high for the system to deal with. Have you tried it with a electrolytic and non-electrolytic of similar uF? --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/ Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/ +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html Note: These links are hopefully temporary until we can sort out the excessive traffic on Repairfaq.org. Important: Anything sent to the email address in the message header above is ignored unless my full name is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. Bill Jeffrey writes: A long shot, but ... Is it possible that your meter actually reads out the equivalent parallel resistance of the cap (yes, I know what ESR stands for)? For most caps (but not electrolytics) this would be a very high resistance - many megohms. Just a thought. By the way, if you didn't get a manual, you can buy the instructional video on eBay for $10. Bill wrote: I recently bought a Sencore LC102 off of e-bay. It was calibrated just prior to sale. When checking caps for ESR, I only get readings on electrolytics, no other type caps. Other caps cause the meter to flash a high value, regardless of control/voltage settings. The meter will read value though for all caps. Am I doing something wrong, or is my meter gimped? Thanks. |
#4
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wrote in message ups.com... I recently bought a Sencore LC102 off of e-bay. It was calibrated just prior to sale. When checking caps for ESR, I only get readings on electrolytics, no other type caps. Other caps cause the meter to flash a high value, regardless of control/voltage settings. The meter will read value though for all caps. Am I doing something wrong, or is my meter gimped? Thanks. Surely it's telling you the caps are good. Try adding a 10 M ohm resistor in parallel with a small cap and see what it says. -- N |
#5
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On Wed, 16 Feb 2005 19:07:02 GMT, "NSM" wrote:
wrote in message oups.com... I recently bought a Sencore LC102 off of e-bay. It was calibrated just prior to sale. When checking caps for ESR, I only get readings on electrolytics, no other type caps. Other caps cause the meter to flash a high value, regardless of control/voltage settings. The meter will read value though for all caps. Am I doing something wrong, or is my meter gimped? Thanks. Surely it's telling you the caps are good. Try adding a 10 M ohm resistor in parallel with a small cap and see what it says. That will not tell him anything useful. ESR is important only when it gets over an ohm or two (depending upon cap value and voltage rating). If you are measuring small value capacitors (1 ufd or less) the ESR meter will not be accurate as the the ESR of the cap will be swamped out by its capacitive impedance. Remember that the ESR meter uses a high frequency test signal so that the capacitive impedance is insignificant with respect to the equivalent series resistance of the capacitor. When the capacitive impedance gets large (small cap value) the meter cannot tell the difference between that and the ESR. John |
#6
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Thanks alot to all that replied. I haven't compared electros to other
types of same value, but will try this. I don't remember the values of other's Iv'e checked, since I only used this meter once, but I'm pretty sure they were of small value. I will reply with results when time permits....working 20 straight days starting yesterday. Thanks again to all. |
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