EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: w2aew on January 26, 2022, 02:19:31 am
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For folks that repair/restore electronics, especially vintage electronics... A common need is to test capacitors for leakage at high voltages. My latest video discusses this, and shows a nice high-voltage leakage tester from the Antique Wireless Association:
https://www.youtube.com/watch?v=3o9FncDRPPg (https://www.youtube.com/watch?v=3o9FncDRPPg)
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Alan, here you go with yet another excellent video. Also, the aesthetic of the tester is pretty nice - it could easily pass as an age-appropriate tester. Thank you for doing these videos.
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Thanks for making this video Alan, watched it yesterday.
There is a simplified circuit available here ;)
https://www.eevblog.com/forum/beginners/is-there-any-practical-or-quick-n-dirty-method-to-measure-capacitor-leakage/msg722332/#msg722332 (https://www.eevblog.com/forum/beginners/is-there-any-practical-or-quick-n-dirty-method-to-measure-capacitor-leakage/msg722332/#msg722332)
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I especially appreciate the absence of humming ahems and hints to a Patreon-hidden page where the mystique of a such tester might be revealed. Instead we here find a clear declaration of the circuit and the actual reality of enough DC volts to test the cap. Less smoke and mirrors, more science.
Thanks.
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Nice project and great video as always Alan. Have you ever used your Tek 576 to look at capacitor leakage?
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This video immediately reminds me leakage tester from "Mr Carlson's Lab". Would be great to have some comparison between them, or at least author's opinion.
I'm not trying to advertise anything or move attention, just my personal interest - whether it is possible to test without applying full specified voltage (hundreds of volts) and still get some valuable result.
Anyway thanks for the video, Alan.
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LR8 looks like a very handy part for this sort of thing.
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Nice project and great video as always Alan. Have you ever used your Tek 576 to look at capacitor leakage?
I haven't, but I'll have to try that out - it's the only other things that I have that can produce that high of a voltage. Of course, it's not pure DC...
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This video immediately reminds me leakage tester from "Mr Carlson's Lab". Would be great to have some comparison between them, or at least author's opinion.
I'm not trying to advertise anything or move attention, just my personal interest - whether it is possible to test without applying full specified voltage (hundreds of volts) and still get some valuable result.
Anyway thanks for the video, Alan.
I've seen the video on Mr. Carlson's tester, but since I'm not a Patreon, I haven't seen the design. I understand it's a low voltage (sub 30V) tester. I would imagine it would be good for testing for any leakage that isn't associated with an insulation breakdown effect, but I can see how the low voltage might effect an electrolytic cap's electrolyte-based dielectric from fully forming.
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but I can see how the low voltage might effect an electrolytic cap's electrolyte-based dielectric from fully forming.
Showing reforming makes great video content. :)
I haven't, but I'll have to try that out - it's the only other things that I have that can produce that high of a voltage. Of course, it's not pure DC...
I was under the impression the Tek 576 could do non pulsed DC as well, I have one but it's needing a full refurb job. Did Tektronix ever release any additional publications or guides on those curve tracers?
I have a couple of variable Fluke 1-10kV DC and 160V DC supplies so they get up there. As a last resort there is the variac or fixed voltage transformer method.
But that circuit you built is nice and functional, better than an old magic eye clunker with a switch knob. I first though what is that, a rheostat or small variac inside? It could be quiet useful for other things as well.
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Hi.
I understand that the schematic for the LV Cap tester is protected by IP, but, there are several videos of followers in which they show their "own" version of the same core.
I unsuccesfully try to get the creator attention on that.
If you do a reverse engineering of the printed circuits you can come to a nice schematic.
I saw that the basic circuit has evolved during some time from its very first appearance.
Now they can select the voltages of the capacitors, I think because they want to measure capacitors under 27V.
The first tester was sourced with three 9V batteries.
Many followers videos show a voltage selector switch to measure 5, 10, 16 and 25V.
My question is, why 5V is not enough to measure a 25V rated capacitor?,
the principle of low voltage does not apply with capacitors under 25V?.
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The leakage current is normally specified by the manufacturer at rated voltage and is voltage dependent as well. Low voltage testing may also not fully reform the capacitor, but reforming at low voltage or current limited can be beneficial.
There nothing stopping anyone making Carlsons or the Awa design for home use, commercializing or claiming ownership of design elements or copying certain design elements is an entirely different matter.