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Discussion Starter #1
Looking for a cable tester that measures capacitance.


I have a pile of old cables that I've worn through over the years. It's never the Jack's that fail as I'd repair them as needed but find that many are partially open etc not so much to cut in and out but enough to effect capacitance and give a muddy tone.

Many are Yorkville and could be replaced for free if I can prove they've failed in the store but this can't be tested with regular cable testers or the highly scientific test of running a rental guitar through a PA. I've been shrugged off a couple times as they can't replace if they can't replicate.

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Many multimeters will test for capacitance or you can get a dedicated capacitance meter.

Mrs Greco got this one for me a a gift many years ago.

I am not sure how/if you will be able to convince L&M to replace a cable based on capacitance readings.
 

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Yep. Most meters. Even cheap ones have it these days. Pro tip: when measuring capacitance it is very reactive - use alligator clips on the leads to prevent the conductivity of your hands from affecting the reading ( wont settle but will keep jumping around)
 

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One can usually know the capacitance of a cable up front by knowing the specs of the cable used and its length. So, a 39pf/ft cable that is 20ft long will have an estimated 780pf of capacitance. Of course, if you bought a cable of unknown wire provenance (e.g., in the $20 pile), such specs are largely unavailable and measurement becomes the default.
 

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Discussion Starter #5
But if the number is way out of wack like a few thousand pf wouldn't that prove its wack?

Just trying to capitalize on the warrenty.

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A few of the challenges, not that I disagree, just to tell you a few things you are up against.
-If it was a couple thousand pF more than a spec. then yes, I'd call it defective. But if you measured 10 new ones off the rack and found a wide range, then you would have to determine if it was within a normal range or not.
-what is the warranty and what causes change in capacitance? I would think a breakdown/change in the % shielding. This would probably be considered a 'wear & tear' item, so may not be covered by 'manufacturer defect' type warranty.

It is interesting to me that you are able to hear these kind of changes in your cables that do not otherwise have dead/alive type faults. I've never paid that much attention but am curious what kind of numbers you would get, and how big the difference would be that seems obvious to you.

A side note about cap function on multi-meters. (when checking actual caps, not cables) Cap function on a DMM will see a leaky cap as having higher than marked capacitance (beyond tolerance). It is not really that high but will be reported that way by the meter function. So if you are measuring a cap and your meter tells you it is way too high in capacitance, it is leaky. A dedicated cap meter will report the actual capacitance but show it to be defective by other test parameters, like ESR or Q.
For example, if I check a leaky electrolytic with my DMM set to 'capacitance', it tells me a cap marked as 10uF is measuring 28uF. It is not that the cap's value has gone up, but a limitation of the meter function. If I test the same cap on my dedicated LCR meter, it tells me the capacitance is 10uF, but way out of whack on ESR and Q compared to a new, known good cap.
A cap can not drift up to some higher value.
 

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It is interesting to me that you are able to hear these kind of changes in your cables that do not otherwise have dead/alive type faults.

If it was a couple thousand pF more than a spec. then yes, I'd call it defective. But if you measured 10 new ones off the rack and found a wide range, then you would have to determine if it was within a normal range or not.
-what is the warranty and what causes change in capacitance? I would think a breakdown/change in the % shielding. This would probably be considered a 'wear & tear' item, so may not be covered by 'manufacturer defect' type warranty.
The above is (specifically) what interests me.
 

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How are the cables in question normally stored? Are they repeatedly coiled up tightly in a manner that might compromise any of the internal layers, or just loosely sitting in a box/crate?

Perhaps it is best to begin with measuring their series resistance from plug tip to plug tip. One of the reasons why buffers are used to conquer cable capacitance is because cable capacitance "matters" to the extent that the series resistance of the hot conductor is low or high. Maybe your problem stems from a dysfunctional plug.
 

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Proving a manufacturing defect would be difficult to do for your old cables. (Tho I admit I'm unfamiliar with their limited warranty). Over the years, wear and tear would take some toll on both the braided shield and the internal insulator(s) that would affect capacitance. Tight kinks and stress, however temporary, would stretch braid, compress the dielectric (insulator) whose resiliency may have limitations. You'd be challenged to prove your cables were run straight between devices forever with no human interference (ohh.. yeahhh) , that'll never happen. I think the best you could hope for would be to determine what to pitch, or cut up for shorter patches with more testing. Changes in capacitance that could would be localized to small sections of cable might be considered have been used in a 'hostile' environment ( I have to chuckle when I say that, having been exposed to some large cabling situations. )
 
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