Just wow. snake oil electrolytic capacitor checking method

[Mark19960]

Yeah.... I got sent this one and it's too good of a laugh to not share it.



  

CB radio techs/shops certainly know how to come up with some of the most ridiculous snake oil.
This one is ... inventive.

[paul cotter]

Yeah, idiotic . That guy should desist from component level repairs.
PS: what is the point of the Bird wattmeter on the video?

[SteveThackery]

I'm trying to work out what his misunderstanding could be based upon. He seems to be finding lots of caps with their -ve terminal a few hundred millivolts negative wrt the chassis. (I'm assuming the DUT is powered up?)

That alone seems a bit strange, although how it relates to faulty caps isn't clear to me. I presume he is looking for leaky caps, rather than open circuit or out-of-spec capacitance.

Anyone any idea where he got this idea from? And why so many of the caps have a -ve terminal slightly below the chassis potential?

[Bud]

8 subscribers

[Mark19960]

I'm trying to work out what his misunderstanding could be based upon. He seems to be finding lots of caps with their -ve terminal a few hundred millivolts negative wrt the chassis. (I'm assuming the DUT is powered up?)

That alone seems a bit strange, although how it relates to faulty caps isn't clear to me. I presume he is looking for leaky caps, rather than open circuit or out-of-spec capacitance.

Anyone any idea where he got this idea from? And why so many of the caps have a -ve terminal slightly below the chassis potential?

I am familiar with the radio and that series of radio. It's one of the "10 meter" radios that's basically a CB radio.
There are 2 grounds on a lot of those radios. The chassis ground (which he calls chastity in the video) and the DC ground.
He has clamped onto the chassis, which is isolated in reference to DC.
As to it's power status I don't know. This is a clip from a larger video I haven't seen. Only this clip is making it's rounds.
Several of the capacitors touched are bulk caps, one is a DC blocking cap for the audio amplifier, etc etc.

As to the idea? No clue. I have never heard of this method, and I suspect it's "CB shop" invented.

[paul cotter]

The case of an electrolytic cap will show some volts due to leakage but is NOT diagnostic, of anything other than random leakage.

[nonius_]

The case of an electrolytic cap will show some volts due to leakage but is NOT diagnostic, of anything other than random leakage.

Testing to the case is actually a method of checking capacitors that Huntron recommends in one of their product videos:

But that's using an analog signal analyzer though....

[Edit: I made a link with a time stamp, but the video doesn't seem to jump to the correct spot... anyway, the method is shown starting from 2'08" ]

[thm_w]

Interesting technique with the huntron, though SMD caps almost always have plastic insulation on them so you'd have to poke through that on those. Definitely not dropping $6k on one. https://shop.huntron.com/Trackers_c_11.html

[Edit: I made a link with a time stamp, but the video doesn't seem to jump to the correct spot... anyway, the method is shown starting from 2'08" ]

It only works for a link, if its embedded it doesn't work youtube.com/watch?v=GM8TYGkEywo&t=128s

[nonius_]

Definitely not dropping $6k on one.

Neither would I But building something that's good enough for most purposes is easily within range of most people. After all, it's just a glorified 'octopus'-tester....

Mine was based on ESP's design ( https://sound-au.com/project119.htm), with a few extra things added to make it a more universal instrument. I intend to build another version (stand-alone unit, with built-in CRT, probably by hacking an old oscilloscope) that will also measure at different frequencies, by using a sine-generator and audio-amplifier).

[SteveThackery]

Testing to the case is actually a method of checking capacitors that Huntron recommends in one of their product videos:

I don't get it. I've used a Huntron Tracker myself in the past. In the video he puts the black lead on signal ground, and the red lead on the -ve terminal of each capacitor, looking for "leakage". For things like decoupling caps he will most likely find a dead short, not leakage. For other caps, I don't understand how the Tracker finds leakage.

However, this might very well be what's behind the technique in the original video. What a fascinating mystery!

[paul cotter]

Hi Steve, to my way of thinking one can only check a cap for leakage with a least one terminal disconnected from the circuit in question.

[Mark19960]

He isn't using a Huntron in the video.
This is a CB shop. They don't have the foggiest idea of what a Huntron is.
Just the DUT and a DVM is how this "method" works.
The DUT need not even be powered up according to his "method"

Some more clips are going around amongst current and former colleagues where this chap doubles down on just looking at the voltage on the metal can is all you need.
The value isn't important. the fact that the DVM flashes a minus, is all that is needed.
If it flickers "-" on the DVM its a bad cap.

Naturally, things just don't work that way.

[SteveThackery]

He isn't using a Huntron in the video.
This is a CB shop. They don't have the foggiest idea of what a Huntron is.
Just the DUT and a DVM is how this "method" works.
The DUT need not even be powered up according to his "method"

Did you watch the correct video? It's by Huntron and shows the Tracker in use. It shows electrolytics being tested by connecting the black wire to signal ground and the red wire to the case of the capacitor. As I say, I'd expect a lot of them - being used for decoupling - would show a short circuit. So I don't understand why it works.

I also suspect this is behind that guy reading negative voltages on the capacitor cases - in his mind showing them as faulty.

[Mark19960]

Did you watch the correct video? It's by Huntron and shows the Tracker in use. It shows electrolytics being tested by connecting the black wire to signal ground and the red wire to the case of the capacitor. As I say, I'd expect a lot of them - being used for decoupling - would show a short circuit. So I don't understand why it works.

I also suspect this is behind that guy reading negative voltages on the capacitor cases - in his mind showing them as faulty.

I did see the Huntron video yes, I should have been more clear which video I was referring to. Apologies.
I have seen one in action years back but I am not sure how it works.

As to the chap that's using a dvm to check their voltage on the case....
There are a few more videos of him going beyond quadrupling down on this being a valid method to check for bad caps.
He's gotten a little angry about being called out, saying that EEs around the world know about this DVM negative flashing voltage method.

I don't know any, and I can't find one.

[Xena E]

Does it grate on anyone else's nerves that the Huntron tester display uses upper case 'K' for kilo on its display? (Also a reason to hate LT Spice 😁)

Essentially all that device does is the same as stuffing the horizontal timebase signal across the DUT to create the display, like a scope' and generator, just less versatile.

Don't diss the guy in the first video! He just does CB repair part time when he's not in his crystal meth lab, M'kay; he probably also believes that flashing the main beam on his pickup truck at the stop lights when he's drunk means he can drive straight on... he's just stoopid.

Chastity... priceless! I'm using that one.

[paul cotter]

Chastity? Hmm, never really appealed to me, though I'm getting a bit old for that sort of activity.

[SteveThackery]

Does it grate on anyone else's nerves that the Huntron tester display uses upper case 'K' for kilo on its display? (Also a reason to hate LT Spice 😁)

Yes! It's amateurish.

[paul cotter]

I guess I will be in the bad books then as I often make case errors. My excuse, I'm just an old fogey

[Bud]

I think what they measure is stray voltage across the long path from where the meter's negative probe is connected to the device's chasis, all the way through the mounting hardware and PCB ground traces to the capacitor's shell, using high impedance meter input. I think if they switch the meter to AC mode they will measure even higher voltage. I'd like to see the meter switched to low impedance, or better yet measurement repeated with a capacitor desoldered.

[Xena E]

I guess I will be in the bad books then as I often make case errors. My excuse, I'm just an old fogey

You're forgiven!
I'm not much bothered as long as I can understand, notation, grammar, spelling... I'm possibly the biggest culprit for the latter, (struggling dyslexic), but so called professionals who misuse the upper/lower case, or disrespect eponymous units grinds my gears for some reason. Writing Khz or similar, instead of kHz, 😬 and I may just have to break out Maxwell's Silver Hammer again...OK?

I think Bud has made a valid point, the guy is just picking up on random crap with his meter so it's just a game of capacitor roulette. I don't suppose he has offered any sensible reason why he thinks his testing method is valid.

[AVGresponding]

It sounds like they are observing dielectric absorption in action. I hesitate to use the word "measuring", as that would imply something meaningful derived from the process...

[SteveThackery]

Writing Khz or similar, instead of kHz, 😬 and I may just have to break out Maxwell's Silver Hammer again...OK?

One rule I disobey without apology is the space between the unit and the number. For example: 12 V, 44.1 kHz, 5 kg. That is what the international standard says. For me, these look much better: 12V, 44.1kHz, 5kg.

I think there is a strong case for joining the unit and the number, because it emphasises the relationship between them.

[Xena E]

Writing Khz or similar, instead of kHz, 😬 and I may just have to break out Maxwell's Silver Hammer again...OK?

One rule I disobey without apology is the space between the unit and the number. For example: 12 V, 44.1 kHz, 5 kg. That is what the international standard says. For me, these look much better: 12V, 44.1kHz, 5kg.

I think there is a strong case for joining the unit and the number, because it emphasises the relationship between them.

You're safe Steve, I do that too! Also for the reason of clarity in reading.

[paul cotter]

Me too, that makes three of us.
I have a query about electrolytics that I never previously thought about, despite using them for over 60years. In a double ended axial cap one lead is obviously connected to the case(the -)- in a single ended axial cap is the case connected? I'm too lazy to root out some caps to test this! 

[Xena E]

Me too, that makes three of us.
I have a query about electrolytics that I never previously thought about, despite using them for over 60years. In a double ended axial cap one lead is obviously connected to the case(the -)- in a single ended axial cap is the case connected? I'm too lazy to root out some caps to test this!

Do you mean radial cap?

The answer is floating in the common form of radial cap with two leadouts and plastic sleeve. The case is in contact with the electrolyte but normally neither electrode, though most high voltage cans are tied to negative I think... very often explicitly the negative connection, sometimes marked on old components "can not isolated".