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- Опубликовано: 22 янв 2022
- This video discusses the basics of capacitor leakage, and how to test for it - focusing on the DC Leakage Tester available as a circuit board from the Antique Wireless Association. Here are the links for this video:
Antique Wireless Association DC Leakage Tester PCB:
www.antiquewireless.org/homep...
Some good info on old electrolytic capacitors:
conradhoffman.com/capchecktut.htm
RadioWild's RUclips Channel:
/ radiowild
Notes from this video:
www.qsl.net/w2aew/youtube/Capa... 
Наука
Thanks for the channel credit! No one has ever thanked me for handing over old, crusty, leaky capacitors! 😄
For new comers to the hobby you may wonder why we test these capacitors at high voltage and look for leakage and it's because of where they are used in older vacuum tube equipment. Many of these paper and wax capacitors are used to couple a signal from the plate of one stage to the grid of the next stage. And if the capacitor has leakage it will allow some of the plate voltage to "leak" into the grid of the next stage. This potentially results in damage to the tube receiving this leaked voltage. Alan, thanks for the video and the info on the tester.
I'm an old timer in the hobby, and I too wonder why you would test them. If you see paper and wax capacitors in an old piece of gear, remove them and toss them.
W2AEW : A tech guru with a lasting legacy! Thanks for ALL you do!
Comparing to all videos in you tube I watched , this is definitely the best video for capacitor testing for leakage . The best explanation , the best and clear demonstration, the info how to build the test device ! I am impressed! Thank you very much sir for the free education and good video !
You are SUCH a great instructor... thank you again (and again). Been working with electronics for over 60 years, but I always learn something new from your great vids; you explain mysteries I have "glossed over"..i.e. made the thing work, but wasn't always sure why.....
Thankyou for teaching about Capacitor Leakage.
Another top tier video that will be used as a GREAT reference around the WORLD for as long as RUclips exists ( ♾) Thank you! 🙏
Good stuff Alan! I need to get one of the AWA testers for my bench. It should be noted that not only ancient caps die. My SEC 1340M power supply died an untimely death due to modern electrolytic caps that were part of the "Capacitor Plague" (2007 to 1999). en.wikipedia.org/wiki/Capacitor_plague. These bad caps mostly impacted computer equipment of that era, but also made their way into a lot of other gear. The AWA tester would be great for the caps in the high voltage side of switch mode power supplies.
Nice gadget. I bought an Eico 950B some time back for performing this particular job. I find that I don't use it all tha tmuch, though. For a while I was doing restoratoin on a fair amount of older equipment, and I'd start by replacing pretty much *all* of the electrolytics and any of those wax-coated paper caps without even testing them. They were a real problem in older radios when we're talking about plate-to-grid coupling caps for the audio power output stage. These days I've pretty much given up on that stuff, and am enjoying my retirement, though one of these days I should probably get to overhauling that 1946 RCA console radio I have sitting here. :-)
The big problem with those old paper caps was two things. One was the fact that the cardboard tube and wax sealant wasn't perfect, and eventually moisture would get in there. The other was that the paper wasn't acid-free, so you'd invariably end up with problems. Changing the case to a plastic encapsulation as with those "bumblebee" caps helped with the moisture ingress but not with the acid paper part of things. At one point I recall that there was a capacitor out there with both paper and a plastic film, but those aren't a whole lot better.
Electrolytics are a whole 'nother story. If they're 50 or 60 years old, they're gonna be dry, and at the very least lose most of their capacitance. I see where some people have a go at re-forming them, sometimes going to the trouble of building a special gadget to do that job, but personally I've never felt that it was worth the bother.
Another fantastic video Alan keep them coming!
Top notch video, very well presented and easy to follow and understand.
Thanks for the great video Alan. Ordered mine yesterday. Can't wait to get started on it.
I got mine built and it works great. I messed up the pot wiring and counter-clockwise rotation increases voltage. Oops :). I appreciated all of your build tips.
Useful, thanks! Your presentation is clear and unhurried which really works for me.
Alan, this is yet another excellent video!
Interesting how electronics hobbyists rarely think of leakage during repair. I did a few videos on my channel about this but in my case I ended up using a power supply and, for higher voltage, an insulator tester.
By the way, nice capacitors! I just changed a few on my grandparents' radio and the leakage on an 80yo wax was incredibly small for the age - replaced anyways, but still...
Thank you
Nice video! One note, though: I'd've mentioned (for electronics newbies) that if they connect an electrolytic backwards at high voltage that there's a risk of explosion. So they ought to wear eye protection or have a shield (like a book) between them and the capacitor.
YOU CANT IMAGINE THE JOY OF HEARING YOU ON 40m late at night here in Amman Country of JY
73's
Wow - thank you! I wonder what the date/time(Z) was that you heard me on 40m?? If it was CW, I was running probably only 25W, so getting a signal into JY is very nice!
@@w2aew when I sent you this msg you where sending CQ on 7.055 then again u QSYed to around 7.061 Mhz and yes on CW HiHi. So it was between 02:38 and 02:44 Zulu. Im using a Homebrew Regen Receiver. I confirmed its you on both SDR and Ham Alert
@@khalidtarawneh2289 That is incredible! When I was calling CQ on 7.055, I was using my QCP+ running about 3W of power, and then using my TS-870S at 20W on 7.061. Amazing that you heard me with a homebrew regen receiver - wow!
.... Well done Mate, articulate, informative, entertaining, broadcast quality.
I was thinking of a shielded compartment on the RH side, negating the need for eye protection.
seems like EL-caps are the 1st thing to keep in mind of a problem in old and new equipment, even some laptops have recalls on caps 🥺thanks for the great trouble-shooting info 🥳🥠☕
Perhaps Add an LED above the discharge switch or by the DUT which visually alerts you to some DUT voltage above a threshold.
Thank you again, Alan , very much ! Simple and nice explanation ! Best Regards
nice video... plan to get this PCB. thanks for sharing!
Thanks for the great video Alan
Love the old meter! Nice touch.
thank you. I'm so glad you exist. Greets from germany
Very good information; thanks for sharing your knowledge.
Thanks for the demonstration I prefer the vintage testers myself as I’m a sucker for anything with a magic eye tube. I recently did a simple restoration on a Lafayette capacitor analyser. It was an easy repair. I’m not sure how much I will use it as I don’t trust old wax or electrolytics and just change them out. The reforming function may be useful. I keep old capacitors just for the purpose of testing and demonstrating the various failures. Have a look if you get a minute it’s a nice tester. Probably came out the Trio / Kenwood factory in Japan back in the day. I will check out the restoration channel you mentioned
Nice demonstration. Nice tester too. Thanks.
Excellent content, I need something like this. At the moment I only have a multimeter and one of those German transistor testers that test ESR at 1.1kHz. Thank you for the video!
Happy new year Alan - as always your video and information is right on target. So now I will build one of these units. 73 de GI8WFA.
Thanks Alan. Great information.
Excellent instruction, as always, thank you.
are there scary voltages on the POT, any concerns?
Nice video Allen. Thank you.
Very clean build 👍.
The tester is a very beautiful construction. 👍
I love this leak explanations
Perfect video for me, thanks for your share
Another great video!
Nice looking piece of gear !
Loves these videos. Thanks brother. Keep them coming. 73 de W6MGV
Nice job with the tick marks for the voltage adjust knob for each 100 volts.
Especially handy when testing large capacitors that take a long time to charge up.
Nice job.
grate information w2aew
xraytonyb just build the very same tester! Both videos are great!
Being an Aussie I remember a different AWA 🙂 (Amalgamated Wieless Australasia) but sadly no more
I got some AWA test equipment on eBay once "as is, untested".
They had large battery packs in them, which had leaked everywhere. They had dribbled gunk out the back, and the seller had cleaned up the outside of the cases, but not the insides.
Fortunately, I didn't waste much money. I think I ended up just keeping the knobs and bunned the lot.
My BWD equipmet, though, is all solid as a rock. I have a video on my channel about a valve sine wave audio range oscillator that has a speaker in the back of it.
Great Job!
Exceptional !
You tutorials are very helpful..can you do tutorial on timing analysis of i2c and spi communication lines
Looks a lot like the "Little Leakage Checker" - a Popular Electronics 1980s project, with a substitution of a pot instead of a stepped/switched resistor chain and possibly made more sensitive with substitution of a different series resistor (100 ohms in the Little Leakage Checker, for 1ma scaling)....
Popular Electronics Electronic Experimenters Handbook 1987 has the project. Available at World Radio History AND The Internet Archive.....
I built one ( used a 1 meg pot in lieu of the stepped resistor chain) , but gave it away when I got my Sencore LC102.
Ah, a worthy -opponent- addition to my Sprague TO-5. :D
That Sprague TO-5 is super-cool though!!
I have ordered the PCB, but then came ordering the parts...the LR8N3 is 'unobtanium' at the moment -lead times are August 2023 or later here in the UK. Mouser CPC, FArnel, RS are all are all in the same place.. So my kit is standing 99% built - waiting for one part!!
Ugh - sorry to hear that. These guys "claim" to have 2000 on hand:
www.kynix.com/Detail/1207177/LR8N3-G.html?gclid=Cj0KCQjwiZqhBhCJARIsACHHEH_IYGxXArwqFXIDjM4JDUHGorPaJg-qJEE9bFjYKBnGYZ0bnZv285saAsPXEALw_wcB
Excellent... Subbed! SMJ
Thank you so much
For measuring leakage I connect my capacitors to my PSU with the multimeter connected in series(in voltage measuring mode). If the input resistor of the multimeter is in the range of 10M ohm thus every Volt will represent 1uA. Works well for low leakage capacitors, maybe something to make a follow up video of? Thanks for all your good videos.
1 volt across 10 megaohms means 0.1 microamps. You can adjust the range with parallel resistor across the meter to reduce it's impedance (like 1 Megaohm for 1 volt/1microamp, 10k ohm for 1 volt / 100 microamp, etc)
A great project and build. Thank you for sharing. I do have a question about safety. I would think that, if you were testing a faulty e-cap at high voltages, you could end up with a tremendous explosion/bang; correct? If so, maybe a container for the DUT would be needed?
Not a bad idea...
7:48 for the schematic. Also check the description for a link to the kit.
Yea,kinda missing some vital comments there. As was mentioned in video, this is the wiring diagram to the pcb. The circuit diagram has not been published, you may get that if you buy the pcb.
I like radio wild too!
Thanks for another great video. One question: How did you connect the volt meter so that it does not show in the leakage current (the current through the meter movement)?
The leakage current is measured by measuring the voltage across a 1k resistor in series between the capacitor and ground. The voltmeter is connected to the other end of the capacitor and ground. Yes, the small voltage drop across the 1k current-sense resistor is included in the total voltage measurement, but it is *much* less than the applied voltage, so is insignificant.
what transformer is used? just a 115v to 230v step up? I like the low profile.
A dual center tapped 1:1. Secondary is stacked.
do those have official isolation specs or use at own risk
found the datasheet. I like the 229E230 only 2VA would be nice and tiny
I like the enclosure you used do you have a part number for it? Love your videos! Very informative. Thank you
Sorry, I don't. It was something I picked up at a hamfest many years before.
Brilliant
Super info as always Alan. I echo R. Davis about your instruction; that was my trade for 38 years and I always admire your videos. Perhaps sometime you might consider a comparison between your (now unobtanium) AADE and DE5000 LCR meters. I bought the latter since I couldn't find an AADE. Specifically how do they fare for low C and L measurements such as pF caps and small toroids? Tnx es 73 Peter
That's a good suggestion - I'll add that to my long list of future topics. Briefly, I have found that it does pretty well with small values as long as you use the higher (100kHz) test frequency.
nice content thanks
Thx so much for sharing. I have never worked at such high voltages so even at my age there is still plenty to learn. BTW did not see green wire connected to chasis im sure i missed it, but just in case...
It is connected to one of the corner fasteners holding the PCB to the case.
@@w2aew Respectfully submitted: when you split the case you have an unprotected side: the top, meter side, no? (as at 17:33)?
@@rdavis7729 Yes, you do - but you shouldn't be operating it when opened up.
Informative video. Just finished populating the AWA circuit board. Love the retro volt gauge. Where did you get it?
It was in my junk box - probably found it at a hamfest 20 years ago.... It is not new/retro, it is the real-deal old/used vintage stuff.
Thanks for the prompt reply.....but damn😮💨@@w2aew
@@joramkalfa4038 You can search ebay for "vintage panel meter" and might find something similar
Is the components list available online anywhere or do you get it with the PCB? Was going to order, but would like to order the components I need at the same time. The only ones I probably don't have are the transformers. I think everything else is basic caps and resistors. Thanks!
It comes with the board. You can contact them and they'll likely send you the document. Or, you can screen-grab it at 7:51 in the video.
Another great video, Alan! This is the second video I've seen on RUclips reviewing the Antique Wireless tester board. Both seem very positive, so I will have to get one. There is also Paul Carlson's low voltage tester but there is some debate on if its good replacement for a tester which measures the capacitor at its rated voltage like the Heathkit IT-11 or this one. Plus I'm not really in the mood to have to make my own PCB so the AWA one seems perfect.
A few questions for you.
1) you mentioned that the LCR meter will not measure leakage current. However since it can measure equivalent parallel resistance, can Rp be used to qualify the leakiness of the capacitor?
2) I really like the box you chose with the slanted face. Is this something you salvaged from some other gear, or is it available on the market somewhere?
Hi Kurt - In some cases, the leakage can result from high voltage breakdown of the dielectric, which would not be present during a low voltage equiv parallel capacitance test. Yes, the Rp test is still valuable, but might not tell you the whole story. The slanted box is one I had laying around, but there are manufacturers like Hammond, BUD Industries, and more that make slanted front boxes/enclosures still, available from places like Mouser and even Amazon. The only modification I made on mine was to add the analog panel meter to measure the voltage across the capacitor under test. Since it is a 500uA meter and I wanted full scale to read 600V, I used a 1.2Mohm resistor in series with the meter.
Hey great video!, Just noticed the QR code on your notepad, is that unique per page? Can we have a link? Thanks!
A pdf of the notes is linked in the video description.
Can you make a video that is related local oscillator leakage to RF path?
I love it AAA+++ work :)
Alan, I know this is kind of an off-topic question, but would you _consider_ making a detailed tutorial on the proper use of the DE-5000 LCR meter? I can't find a _good_ technical tutorial on its use and I have to admit that I don't really understand its _proper_ use (as a newbie). I was given one as a Christmas gift a few years ago, but reading through the manual doesn't turn "the little light-bulb on" for me, at least not yet. I don't want to damage it or misuse it and miss finding a bad cap (as far as it can find, which I just learned in this video!)
I think I'll order one of the AWA PCBs and build it both as a learning project _and_ to add to my arsenal of test equipment. Thank you for sharing this very educational & informative video and links!
Thank you Bob - I have had a few requests for this, so I will add it to my long list of future video topics.
Check out TRX Lab video #83.
@@outagas2008 Thanks for reminding me of that video! I obviously watched it several years ago and then forgot about it, but would still like to see Alan's version of an "in-depth" tutorial on the meter. (Also, Alan turns on closed-captions, which helps folks like me. ;)
I've already restarted the TRX Lab video to refresh myself with what he presented in video #83. Thanks again!
Great video Alan, Please forgive me for asking, what are you using to display the text/drawings in your video? Is it some type of tablet PC?
In this video, it is a reusable notebook called a Rocketbook. In some past videos, I have also used a e-ink tablet from www.remarkable.com.
@@w2aew Thank you for the reply Alan. I bought a Remarkable last year after watching several of your videos, so I was surprised when I saw you using this Rocketbook. My first thought was that I had missed a new version of the Remarkable. Which do you prefer? The Rocketbook looks to be a bit needier to maintain. Has that been your experience?
@@billsmith396 The Rocketbook advantages are that it is inexpensive, in that it is really a notebook with plastic coated pages - when combined with the erasable Frixion pens, adds the nice ability to have multi-color notes that are easy to convert to PDF. The downside compared to the remarkable tablet is the editing/moving/scaling of notes and diagrams, which is really nice on the tablet. I find that I am using the Rocketbook more than the remarkable tablet these days, mainly for the color aspect.
The bakelite covering shrinks over the decades for the bumblebee caps. This squeezes the paper to together and shorts out the caps. I just replace them. I like the aircraft volt meter used in your tester.
Bakelite shrinks? I've never experienced that. Also, it's not bakelite - it's another type of plastic. The paper inside them degrades over time just like the ceramic and wax encased ones.
I have repaired several trans-ocianics that use these caps. Many had longitudinal cracks as the plastic shrank. I talked to other radio collectors and they had the same issues. Incidentally, the military version does not use these, but mica capacitors instead.
@@jonbutzfiscina1307 I've seen cracks as well and it was my understanding it was from the paper cap inside swelling. Interesting that the military realized that mica was more reliable back then.
Hi Thanks for this vid, I going to get one of these boards, could you answer a couple of questions . What guage wire to get? 14, 12 ? other. other parts you used not specified. additions to
the schematic or changes. the box part number where to get it. Thanks
The wire gauge doesn't have to be large because the currents are all very low. You can use pretty light gauge. I used 18 gauge. You could even use 20 or 22. The most important thing is to be sure that the insulation is rated for 600V or more. The only change/addition I made was to add the voltmeter, which in my case was a 500uA full scale meter, added with a 1.2Mohm series resistor so that it reads 600V full scale. The box I used is something I've had in my junk box for many years, so I can't give you a part number for that, sorry. The same is true for the IEC power entry jack and the lighted rocker power switch.
Excellent video, I have a ready table that I got years ago on the TRX lab channel, with capacitances from 1uF to 5600uF, I tried to post it here but youtube deletes it.
If you can spell out a link for me, I can include it.
@@w2aew see on TRX lab channel itself, in 39 minutes
ruclips.net/video/2HUxuRcPR4M/видео.html
@@eldervieira85 OK, thanks. Looks like it is a table built from the 0.1CV+xxx equation from that Panasonic datasheet. Since different manufacturers have different equations, the values may differ depending on the mfr and capacitor type.
I work on a lot of vintage radios and own an Eico 950B. Is it feasible to add a meter in series with the DUT to determine actual leakage as well as the pass/fail of the eye tube?
I don't know enough about how the Eico 950B operates to answer this question. Probably a good question for someone like Mr. Carlson's Lab.
@@w2aew thank you from ko2fb
Can a hipot tester that is AC/DC/IR (IR=insulation resistance) that can be adjusted from 0.1 to 6k v be used for tests?. I'm just asking because I got lucky with the one off of eBay for cheap and now I got to find a use for it
For the higher voltage caps (100VDC or higher), yes.
Hello,
Where did you buy your unique project box/enclosure?
I've had it laying around in my parts bin for years. You can find them pretty regularly. Popular manufacturers of these slant-front enclosures are Hammond and BUD Industries.
I do usually use my 600v power supply with a Simpson 260 in series. I gradually increase to the rated voltage not allowing more than a few milli amps of current until I get to the rated voltage. I downloaded an acceptable leakage table that shows everything up to 450v. Everything is in microamps. Some caps have as much as a few thousand microamps leakage allowable. That's electrolytic.
I may get that board and build a nice one. Adding the series resistor would make it nice. Gradually increasing the voltage then draining the cap after the test.
Not many of us (myself included) have access to a 600V power supply!
Just add a suitable resistor in series with the capacitor: that will limit the charge current automatically and you don't need to fiddle with the voltage but can just set it to the maximum you want to reach.
This device that w2aew built kinda works like that, but the resistor is too low value, I would add a switch (or potentiometer) to be able to select the resistance of the series resistor, great for reforming caps, even new old stock that you sometimes get for low volume items from Mouser or Digikey.
How accurate or reliable is it for me to test electrolytic caps with 10V input, an ammeter inline with the circuit to measure microamps, a 1K resistor in series with the cap, and a volt meter across the resistor? If I was doing my experiment correctly, most of the caps I tested had only 1 or 2 microamps of current going through them whether by the ammeter or the volt meter (I=V/R). And is 1 or 2 microamps acceptable? All my work is with low voltage stuff, not high voltage.
This method is perfectly acceptable. It's a good idea to include a series resistor so that you don't overload your ammeter in the event that the capacitor shorts out. 1 or 2 uA is likely acceptable for electrolytics, but to be sure, check the manufacturer's datasheet ratings.
Get one of the older Sencor capacitance and inductance testers. They go up to 1k and read out in microamps.
Are you happy with your DER EE DE-5000? The gear is cool overall, but I am annoyed by low contrast LCD (it depends on the angle of view, but the maximum of the contrast is observed at inappropriate angle of view) and by its slowness (how much time it takes to update the readings, to choose right mode in auto-mode, to switch to the correct range of measurement).
I too am curious. I see this popping up on a lot of benches, and I'm thinking of getting one for field work. I hate taking my BK 886 out of the shop. Also looking at BK 880 for travel days.
I'm reasonably happy with it - probably worth the price, but it isn't perfect as you say. But overall, I like it well enough.
I also have one of these meters and find it worth the money, yes it may be a bit slow on auto range..but it's going through quite a few tests in that time. If you want quicker make use of manual modes,also the nice blue backlight puts an end to poor contrast display. The meter also has go/no go function for batch testing (RCL) that can be handy for getting close matching components or sorting out the parts bin. This is a 4wire test meter so also works well with low value resistors (particularly handy for batch test/matching). The meter will pay for itself after a few repair jobs.
I've had one for about five years now. As *w2aew* says, it's not perfect, but I've learned to trust its measurements once I knew what it's actually doing in certain modes.
If the display is an issue, I'd recommend building an infrared-to-USB adapter (3D print the case, find an IR phototransistor and resistor, connect them to a USB-to-serial board) , and using IETs' PC software or sigrok to show the data on a computer monitor.
Could you make sometime a video or videos on transformers, cores, for example an 1:1 transformer, how to choose the core material, how many turns you need and relation with the bandwidth. I found hard to gather proper information on this topic.
I'll add that to my long list of future topics.
What's your opinion of Mr Carlsons low voltage tester?
I've never seen the design of it, so I really can't comment one way or the other.
How would this work for checking coax for breakdown. I guess I should wait to see what the voltage is.. We need a reasonable HI-Pot tester..
Possibly, but you have to be careful about looking for breakdown because of the rapid change in resistance, you have to make sure the tester than handle to current arising from a sudden near-short circuit
Hi...where did you find that old, analog voltage meter?
It's been in my parts bin for many years, but probably picked it up at a hamfest (amateur radio flea market).
Hey Alan...what did you use to cut all the big holes in your box? Whenever I cut large aluminum holes, I seem to get poor results.
I used a stepped drill bit for the small/medium sized holes (the banana jacks, potentiometer, etc.), and as a starter for the larger holes (meter and AC entry jack). I completed these larger holes using a sheet metal nibbler like this one: www.amazon.com/ProsKit-900-215-Nibbler/dp/B000BN60XW/
@@w2aew Thanks Alan...you do nice work!
@@w2aew Hey Alan...one final question. Do you remember where you purchased the sloping face project box you used for this? I can't seem to find one with such a large top surface. Thanks again.
@@stevebailey1682 I had it laying around for years, so I don't remember where it came from. Probably a hamfest find. However, it appears that Hammond Mfg makes them. Available from Mouser: www.mouser.com/c/enclosures/enclosures-boxes-cases/?type=Sloped%20Console
What wire gauge was used for the HV connections?
The wire I had as 18 gauge (much more than needed since it is all very low current), but has 600V insulation rating.
I noticed that terminal 7 on your transformer T1 is installed in position 1 on the PCB.
Yes, I had noticed that too after filming this video, and corrected it.
@@w2aew I did the same thing. I fixed it also. What capacity varistor should I use across the input line?
@@outagas2008 What's strange is - I had somewhat purposefully installed it that way because I figured it was a 1:1 transformer and it wouldn't matter, and that made the labeling readable when looking at the board (I usually try to install components so that they are consistent and readable, such as resistors all oriented the same way). However, I found that the voltage would only go up to about 415VDC. I measured the secondary voltage and it was lower than I expected. So, I figured I would "correct" the orientation for the transformer. Once I did, the output can now be adjusted to 600VDC. Strange. I still am not sure why since the transformer still appears to me to be 1:1...
@@w2aew I was able to get 590V
Are BNC's rated for couple hundred volts?
Typically good for 500v
Would the DMM external connection posts also be at the high test voltage? Thanks Greg
The ones on the top, above the meter, yes.
@@w2aew At 8:30 you said the front "monitor points is across a 1kohm resistor that is in series with the capacitor and high voltage power supply".
I understand that there is only small voltage across the 1k resistor but since the resistor and monitoring points are in the same series circuit as the capacitor under test and the HV ps, isnt the resistor at he same HV potential? I guess the resistor could be on the low side or the return leg with one end connected to ground but if the capacitor is short the HV would be directly across the 1k resistor.
Sorry for repeating my question.
By the way Ive leant heaps from your instructional videos. Many thanks Greg
@@gregwmanning The 1k sense resistor is on the low side. The capacitor under test is fed HV through a high value resistor, so even if the cap is shorted, the voltage across the 1k sense resistor is still low.
@@w2aew I get it now, thanks. Yesterday I ordered one of the PCBs. Regards VK7GWM
You should check out Mr Carlsons Lab. He often restores very old devices.
He built a capacitor leakage tester and shares schematics.
The tester tests caps with a low voltage so no hazard stuff and it's very sensitive up to Giga Ohms if I recall correctly. Think you should check him out.
I am familiar with Mr. Carlson's Lab, he does great work. I've seen the video on his leakage tester, but he only shares schematics of it to his Patreon subscribers, so I haven't seen the schematic of his tester.
@@w2aew Ah OK, I'm a Patreon and it is there, I'm about to build it when I have time.
can we add a 1-15 VDC or 1-150 VDC range.. pretty easily?
The existing design starts the voltage at about 10V, and the available DC voltage is around 600V. Any low-voltage regulator would likely need to be powered from a lower voltage. It would probably be easier to design a lower voltage version, or simply use a lower voltage supply along with a DMM.
Pilot Frixion pens! If only they didn't dry out so quickly when I forget them somewhere
I would like to make a comment and ask a question.
Comment: Please note that the bottom connectors to measure voltage, that you calculate current from on the bottom, could contain a high voltage up to the 400 VDC, if the capacitor being tested is shorted, or close to shorted. You did say that the capacitor is charged with a 18K resistor in series so if it is in series and the 1K is also in series, then you would only see at most about 21 VDC. I have not looked at the schematic.
Question: Is there any possibility that you may have a full parts list and schematic for the exact one you built? I like your design here. Regardless of my comment above, I would like to build one pretty much like yours. Thanks for letting us know, and if if this information would be available.
You make some great videos, and they are greatly appreciated. Thank you.
The 18K resistor is on the power supply side of the DUT, and the 1K resistor is between the DUT and ground. Thus, even if the capacitor is shorted, there will be 19K between the supply and ground which will limit the current. So, even if you get a capacitor short when testing at 600V, the highest voltage at the current sense will be under 32V. The parts list with Mouser part numbers will be provided with the board from AWA. They do not share the complete schematic of the design, although it is fairly easy to reverse engineer. I won't do that here since I want to respect their desire to not share the schematic. The only "extra" parts I used are the old meter movement, a 1.2M resistor to adjust the scaling of the meter to have it read 600V full scale, a IEC AC power entry receptacle (which I had in my parts bin) and the lighted AC power switch (also from my spare parts bin).
@@w2aew Thank you for your reply. I understand about the schematics, and that is no problem. The other components, meter, resistor, receptacle , etc., are also no problem. The entire project doesn't look to difficult. The part about it that I liked is the chassis (cabinet). I guess you made it yourself, and it is not sold somewhere. That is the part I should have included in my original post. That is a good idea, and well done. I like the idea of having the higher voltage only at the top. And, yes to the low voltage due to the 18K and 1K resistors in series, which I mentioned at 400 VDC test voltage the maximum at the bottom connectors would be about 21 VDC. So, with 600 VDC test voltage having less than 32 VDC is good. Well done. I just don't have a lot of time to make the chassis (cabinet).
Thanks again. I appreciate it.
@@TheOmegaman69 I didn't make the case, it is just a project box that I had purchased many years ago - and it was just waiting for the right project! I'm sure there are still folks that make them. Here are a few examples:
www.amazon.com/BUD-Industries-PC-11491-Plastic-Natural/dp/B005T58ZTO
www.amazon.com/BUD-Industries-PC-11493-Plastic-Natural/dp/B005T592P0
www.budind.com/general-use-boxes-aluminum/?load=true#group=series&general_series_cover_style-solid-door=0&general_series_cover_style-screw-down-cover=0&general_series_cover_style-clear-door=0&general_series_cover_style-hinged-cover=0&general_series_cover_style-infrared=0&general_series_mounting_style-flanges=0&general_series_mounting_style-molded-flanges=0&nema_series_mounting_style-molded-flanges=0&general_series_mounting_style-din_rail=0&general_series_mounting_style-rack-mount=0&general_series_features-with-recessed-top=0&general_series_features-without-recessed-top=0&general_series_features-with-battery-compartment=0&general_series_features-without-battery-compartment=0&general_series_features-ventilated=0&general_series_features-with-knockouts=0&general_series_features-without-knockouts=0&general_series_features-not-ventilated=0&nema_series_ip_rating-65=0&series=0-12&material-development=0&material-plastic=0&material-aluminum=1&material-hand-held=0&material-steel=0&material-chassis=0
@@w2aew Thank you very much. You must have had to do some research to find these. Thanks for providing them.
I like the second one you listed, so I think I will go with it. Thanks again.
You stated the old capacitor (location 11:46) tested was 20 micro-amps and thus failed. Then you state toward the end of the video (location 14.28) new electrolytic 450V was passing at 100 micro-amps. How can the new one pass at 100 micro amps and the old one fail at 20 micro amps?
Different types of capacitors have different levels or normal/expected leakage.
The restored pcb design on video.
ruclips.net/video/mIm4d0jy-kY/видео.html
See the READMORE section.
When a capacitors charge time and discharge time are equal, what happens or what is this called? Amplifiers use coupling capacitors per each amplifier stage but when the coupling capacitors charge time and discharge time are equal the coupling capacitor causes what type of problems?
The equality of the charge and discharge time has nothing to do with the capacitor - it is a function of the circuitry that is doing the charging or discharging.
@@w2aew ok when the charge time and discharge time are equal the circuit will cause what type of problems? When they both are equal I'm guessing that is the resonance frequency of the circuitry or it acts like a short circuit ?
@@waynegram8907 It depends on the circuit. If a capacitor is being used to make the power supply more stable, then fast charging and slow discharging is desired. If the capacitor is being used to couple two stages together, you want both charge and discharge to be slow. But, slow charge can lead to "pop" in audio amplifiers when you turn them on.
@@w2aew The coupling blocking capacitor and the miller effect of the tube or transistor in each amplifier stage section is creating an RC charging time and discharge time? Why choose the slow charge time and discharge time for amplifiers?
@@w2aew Most power supplies RC duty cycle is 2 to 98 ratio or 5 to 95 ratio? meaning that the charging time is 2%-5% and the discharge time is 95%-98%? The RC is R is the LOAD of the circuit and C is the filter capacitor value.
Be aware of the BNC part might not hold up to more than 500 V.
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