Products > Test Equipment
LCR vs ESR meter for in-circuit testing of electrolytic cap
indman:
The device for in-circuit measurements of capacitors should have, in my opinion, the following characteristics:
1. Have a convenient form factor so that capacitors can be easily tested at any point in the circuit.
2. Have convenient readability of readings from the display even for people with not very good eyesight.
3. Have simple circuitry with the element base available for repair, even better if it is assembled with your own hands.
4. Have a reliable system of protection against overvoltage and residual voltage in the circuit.
5. For a quick diagnosis of a suspicious element, it is quite enough to determine C and ESR, there is no need to use expensive LCR meters with delicate inputs without protection.
I have DE-5000, XJW01, ST42 but I don't use them for in-circuit measurements, because I use a simple and reliable tool that has never let me down.
Kean:
--- Quote from: tautech on September 11, 2023, 04:22:18 am ---You need use ST42 more and get to know them better. ;)
--- End quote ---
In what sense?
I know they are pretty accurate, but I find the ergonomics aren't all that great for measuring larger parts. A good example is if you are measuring in-circuit and balancing a PCB attached by cables to a chassis. I'd find tweezers difficult to hold let alone read in that situation, and why I rarely measure in-circuit anyway.
Just for reference, attached is a photo of a quick comparison of measuring a 330uF 16V SMD electrolytic with my CKT bench LCR, the Peak atlas ESR70+, and the Shannon Tweezers ST42.
CKT5000: 297uF 330mohm
ESR70+: 306uF 200mohm
ST42: 298uF 341mohm
(edited to fix typo in labels)
The ESR70+ reads ESR a bit low, but that is because it measures at 100kHz whereas the others are set to measure at 100Hz (more appropriate for some random electro).
The CKT5000 and ST42 are set for 100mV test voltage. The ESR70 uses about 80mV (+/-40mV). I didn't check, but I think those are all Vpp (and the manuals don't clarify).
Further tests...
ST42 set for 10kHz reads: 217uF 223mohm ... hmmm?
CKT5000 set for 10kHz reads: 297uF 203mohm
CKT5000 set for 100kHz gives invalid reading: -17uF 189mohm <- this is a good example of where knowing the instrument is important
ESR70 Gold measures at 50kHz which might be better for accurate ESR on a bigger electro than 100kHz of the ESR70+. I just want to know order of magnitude to know if a cap deserves replacement. I am not using it for precision ESR measurement, because for that I'd use the bench LCR and a proper hands off test fixture.
BTW, the CKT5000 is using correction data for my SMD test fixture where I was last measuring single digit pF 0402 capacitors.
tautech:
--- Quote from: Kean on September 11, 2023, 07:54:16 am ---
--- Quote from: tautech on September 11, 2023, 04:22:18 am ---You need use ST42 more and get to know them better. ;)
--- End quote ---
In what sense?
I know they are pretty accurate, but I find the ergonomics aren't all that great for measuring larger parts. A good example is if you are measuring in-circuit and balancing a PCB attached by cables to a chassis. I'd find tweezers difficult to hold let alone read in that situation, and why I rarely measure in-circuit anyway.
Just for reference, attached is a photo of a quick comparison of measuring a 330uF 16V SMD electrolytic with my CKT bench LCR, the Peak atlas ESR70+, and the Shannon Tweezers ST42.
--- End quote ---
One needs ask oneself how much accuracy is really necessary.
One also needs remember every passive has a tolerance spec that we need factor into any measurement to determine if the passive is really faulty or just outta spec where the circuit/DUT won't operate as designed.
I've been using SMD tweezers as my primary passive test device since ~2007 and as you can stretch their legs to 1"+ so most passive devices can be easy tested and for those that can't an extension wire fixes that.
The Peak Atlas products have been of interest except for the fact you can solder wires on larger components the need for a test device with flying leads has never arisen as they are universally slower to use than one handed SMD tweezers.
Any diagnostic technician should question every measurement so when something doesn't look right we first suspect the connection then the DUT itself < all occasions when probe or tweezer tips haven't penetrated oxides or conformal coatings....whom of us have never questioned a measurement ?
YMMV but quality SMD LCR tweezers have been a godsend for all my electronic work as they provide quite sufficient accuracy and unsurpassed speed and ease of use.
RiRaRi:
As i have seen new ESR70 gold measures at 50-100kHz. So you would say that LCR tweezers are more accurate for ESR then lets say ESR70 even for in-circuit?
alm:
--- Quote from: RiRaRi on September 11, 2023, 03:34:06 pm ---As i have seen new ESR70 gold measures at 50-100kHz. So you would say that LCR tweezers are more accurate for ESR then lets say ESR70 even for in-circuit?
--- End quote ---
ESR is frequency dependent, so you can't say a measurement at 100 Hz is more accurate than a measurement at 100 kHz. If anything, the latter is an easier measurement since the value will be higher. I'd say depending on your goal a measurement at the frequency specified in the data sheet (100/120 Hz, 10 kHz or 100 kHz depending on the intended applications), or the frequency it will be used at (100/120 Hz for a linear supply, but dozens of kHz for a switcher) is the most useful.
For an in circuit ESR measurement accuracy is not something I care about. It's a ballpark measurement that's about orders of magnitude. For accurate measurements you want to measure out of circuit with a meter that can measure at multiple frequencies like the DE-5000.
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