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Old 24th November 2015, 03:44 PM   #1
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Default fake caps ! whats your opinion.?

Click the image to open in full size.I bought these caps of ebay a few years ago they are 10,000uf 80v elna I have just got a peak atlas ESR 70 which I hope is good enough to test caps with . the caps test within standard tolerances and esr seems nice and low the caps have the elna sword vent pattern what are your thoughts on these being fake . would be willing to cut one open if that's any good .


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Old 24th November 2015, 03:53 PM   #2
rayma is offline rayma  United States
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Quote:
Originally Posted by glennjarrett View Post
the caps test within standard tolerances and esr seems nice and low the caps
have the elna sword vent pattern what are your thoughts on these being fake
You should reform them with an 80V power supply, and a 10k 1W series resistor for each capacitor,
to limit the current to less than 10mA at full voltage. Then slowly increase the voltage
from 0V to 80V over an hour or so while monitoring the drop across the resistor. When the
drop across the 10k is less than 10k x 1mA or 10V, the capacitor has reformed enough to use.

Last edited by rayma; 24th November 2015 at 04:00 PM.
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Old 24th November 2015, 04:09 PM   #3
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First you demonstrate that the caps are within spec. then you want to cut them open to prove what - that they are full of aluminium foil, interleaved with absorbent material and noxious, sticky electrolyte? You can't prove whether these parts are genuine or not by internal examination. The proof is in performance and this is only measurable with the capacitor intact.
So are you just bored or inquisitive to know what's inside?
https://en.wikipedia.org/wiki/Electrolytic_capacitor
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Old 24th November 2015, 07:20 PM   #4
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Originally Posted by glennjarrett View Post
I have just got a peak atlas ESR 70 which I hope is good enough to test caps with .
They are excellent little meters, mines had a LOT of use

As for your caps?, I'm with the rest - they look fine, why would you suspect they aren't?.
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Old 25th November 2015, 09:35 AM   #5
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by rayma View Post
You should reform them with an 80V power supply, and a 10k 1W series resistor for each capacitor,
to limit the current to less than 10mA at full voltage. Then slowly increase the voltage
from 0V to 80V over an hour or so while monitoring the drop across the resistor. When the
drop across the 10k is less than 10k x 1mA or 10V, the capacitor has reformed enough to use.
The standard specification from all the manufacturers, I have read, state that the electrolytic capacitor must be reformed before any testing.

And reforming last week is no good.
It must be freshly reformed specially for the testing.
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Last edited by AndrewT; 25th November 2015 at 09:37 AM.
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Old 25th November 2015, 10:26 AM   #6
JMFahey is offline JMFahey  Argentina
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I think those are FAKES and you have been ROBBED BLIND.

Both *claim* 10000uF , yet one is a whopping 682uF short, the other one missing 650uF ... and so on.

But it's your fault, you should have *weighed* them when you received them, only way they were not filled to the top with capacitance, but some was left out.

Or at least, if a microgram calibrated scale was not nearby, you could have applied an old, savvy buyer's trick: you should have shaken each of them vigorously by your ear, any splashing inside would mean that vital capaciliquid was missing, and cheap *air* (ugh !!!) bubbles are present instead.
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Old 25th November 2015, 11:02 AM   #7
jvhb is offline jvhb  Europe
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That is serious sarcasm from south america..
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Old 25th November 2015, 11:10 AM   #8
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Hi JMFahey
well seeing the capacitor tolerances are +/_ 20% so 20% of 10,000uf =2,000uf being 600uf out is well in tolerance
I have also weighed all 6 caps with scales accurate to 1/10 of a gram and they all weigh between 70.1g and 70.5g so less than 0.5 grams between them !
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Old 25th November 2015, 11:12 AM   #9
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That is serious sarcasm from south america..
Harsh words indeed !
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Old 25th November 2015, 01:30 PM   #10
wg_ski is offline wg_ski  United States
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Quote:
Originally Posted by JMFahey View Post
But it's your fault, you should have *weighed* them when you received them.
That's the very first thing you should do. If I get a cap that's suspiciously light or feels hollow your damn right I bust one open and see what's inside. If they feel solid and measure in spec they're probably fine. When you do get a fake, they're going to put something really undersized in there - like the "10,000uf/50V" caps that had a little bitty 2200 soldered to the end cap. I finally got one of these - but it was a batch of 30,000uf/60V CG cans (paid like $5 a pop). The darn things felt empty - and sure enough there was a cheapo 4700 uf leaded cap hooked up inside it.
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