EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: xrunner on May 27, 2016, 01:49:59 pm
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Ah that's better! I hate those rubber rings with a passion.
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Better buy yourself a set of decent fixed 1:10 Testec probes. The Rigol probes are somewhat use able, but that is all to say about.
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Better buy yourself a set of decent fixed 1:10 Testec probes. The Rigol probes are somewhat use able, but that is all to say about.
Yea I know, I need to do that soon.
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Right, where's me knife..
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What's wrong with the rubber rings?
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What's wrong with the rubber rings?
The ones around the BNC are slippery and badly shaped. Just plain awkward to get on and off.
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What's wrong with the rubber rings?
The ones around the BNC are slippery and badly shaped. Just plain awkward to get on and off.
Right. They suck - I usually have to pull on the cable to get 'em off the scope. Too slippery.
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What's wrong with the rubber rings?
The ones around the BNC are slippery and badly shaped. Just plain awkward to get on and off.
Right. They suck - I usually have to pull on the cable to get 'em off the scope. Too slippery.
I wouldn't recommend your *mod* universally.
For those with an unearthed mains supply no insulation of the BNC connectors may expose the user to some stray voltages.
Furthermore for those that isolate their DSO's from mains ground to enable scope connection without GND loops, this *mod* would expose the user to the same voltage as to where the probes reference lead is connected. :--
This also applies to all the exposed BNC connectors when doing *isolated* measurements.
Be careful out there. ;)
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All the scope probes I used for 24 years in industry didn't have that rubber ring, and even the Testec probes recommended in this thread don't have a rubber ring, neither do most of the replacement scope probes. Ultimately you need to understand what you are doing.
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All the scope probes I used for 24 years in industry didn't have that rubber ring, and even the Testec probes recommended in this thread don't have a rubber ring, neither do most of the replacement scope probes. Ultimately you need to understand what you are doing.
Exactly. :-+
One must remember there's many DSO/scope newbies on this forum that aren't aware of all the dangers than can arise from probing DUT's, hence my warning. ;)
All my old probes don't have insulated BNC's either and I've used then at elevated isolated voltages KNOWING the risks, and with metal cased CRO's too. :scared:
Brings new meaning to: IT'S ALIVE. :-DD
Most new DSO's however are supplied with insulated BNC's on probes as OEM for good reason IMHO.
Be careful out there.
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Most new DSO's however are supplied with insulated BNC's on probes as OEM for good reason IMHO.
Be careful out there.
To add to your concerns though, which I respect, be aware that even if you connect a scope probe to channel 1, with an insulated BNC, guess what? If there is a danger in touching it, all three other channels outside BNC metal is now connected to the potential of the channel 1 outside barrel. So if you touch any of the other three channels with your finger accidentally, you now get zapped even though channel 1 has a rubber ring ...
(https://lh3.googleusercontent.com/5cHEhpIwHh6FnZ53pOQrv1ExV2tk9KbwL7rWl9iDKgEXBt1umlNIzWW1GlaLqXHfmRzEB50Nq9Lhchi7kozoRJX7cxlLE1G1tRBbIXOfYXjrH2lfckzbUuV2qxHXheWDjixWgteR76Jp-Gbn8hVvL8hHBdtxq6LrqBv_KfQGXWLyV2mXz3yODAi5BqIEr0v_BpOgnAr9lL8gyyTDVltN5Zdt1xijMEIHttfOAMjbJGzJPuldqAaRUKaE6WikzfAfSzehBKVI6Mfil5ctaQYNQUSlHQTCcbllihTvTe1X-olywkDo_MEf6FFHrXl33C3V9ZTLfjkz1Ot_feM-emZcA69Ue2DaejLGBWe4HHyQEqFFPPx9EEiQ0j0lJl-P8oAHGfrITC30_O7bFHxtC8k5y1XKqg3_udUbEAmHukceJaKIRArIBgZdDJNqf7utDE2Zm9JyKBjforWOWji70iDUDQV5xE94kE_hYkh-vHb0N2u5MMJ8uR0mNYurRiMK3owmLSb_OuETi_M7EQ3s1T6bd-_t5owUoaq6gFNM_efK3PsmlIsaj1MRHexhq3C3cn5CUHZhCviCWMBPihr1kSsRyusR3q7IIWg=w614-h244-no)
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The ones around the BNC are slippery and badly shaped. Just plain awkward to get on and off.
Well, maybe one likes them and one doesn't. I think that they're a quite nice touch and look way better than just blank BNCs. Rigol could've used a grippier surface pattern, but overall I can't recall that the connector ever slipped out of my grip.
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Utility first, looks second. It's a scope probe, not a car.
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Ouch! You circumcised your probe!
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Most new DSO's however are supplied with insulated BNC's on probes as OEM for good reason IMHO.
Be careful out there.
To add to your concerns though, which I respect, be aware that even if you connect a scope probe to channel 1, with an insulated BNC, guess what? If there is a danger in touching it, all three other channels outside BNC metal is now connected to the potential of the channel 1 outside barrel. So if you touch any of the other three channels with your finger accidentally, you now get zapped even though channel 1 has a rubber ring ...
Yes, as explained in my first reply:
This also applies to all the exposed BNC connectors when doing *isolated* measurements.
Be careful out there. ;)
Post edited to highlight this ^^^
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Yes! I find the raised plastic makes removing them difficult! I gotta try that.
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On a more serious note. Isn't it common to plug in a non insulated bnc tee, for example, to terminate into 50 Ohms? There will always be a potential issue if you defeat the grounding of the scope, no? As Mr. Carlson says, "you do so at your own risk".
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On a more serious note. Isn't it common to plug in a non insulated bnc tee, for example, to terminate into 50 Ohms? There will always be a potential issue if you defeat the grounding of the scope, no? As Mr. Carlson says, "you do so at your own risk".
Absolutely.
If the oscilloscope industry wanted to really protect people, they would do a complete connector solution, something like DMMs, where not only the internal but the external connections are completely insulated from the user. As it is now, you can still touch the same potential on other BNCs that one or more probe covers are insulating you from, as has been pointed out.
Do all of this testing and modification at your own risk!
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You can then add heat shrink to get a new cover that doesn't slip. And put plastic caps over the unused BNCs when probing high voltages, although those tend to get lost.
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You can then add heat shrink to get a new cover that doesn't slip. And put plastic caps over the unused BNCs when probing high voltages, although those tend to get lost.
Who does the ergonomics at Rigol? The thing is, I wouldn't even have considered cutting the rings off if they had been easy to remove. They are too slippery when puling away from the scope. That could have been easily fixed simply by the way the molding was done.
There is no need for me, or many users, to have a rubber ring there in the first place, because that metal is grounded and safe. But if they want to put a rubber ring on it, it needs to be easier to grab.
And as I've said, many replacement probes, which are in fact made better anyway, do not have rubber rings there.
Probing electronics is inherently a risk, and in the end if you don't have a clue what you are doing, you should not be probing with any test equipment!
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I doubt whether any of the Asian DSO manufacturers make their own probes.
My investigations have found at least 3 scope probe manufacturers and for at least 1 of them it's their core business.
Most offer insulated BNC's in a range of BW's but in the case of these Rigol probes IMO they've chosen unwisely in the way they commandeer most of the physical space available around the BNC's and force those without the fine fingers of most Asians to struggle with connection/disconnection.
Spacing between BNC's is also an issue that was bought up in other threads.
But overall IMO how the front panel layout has been organised hasn't helped matters...ie. by placing the larger knob of channel attenuation directly above the BNC's. :--
Knob swap time....much safer than removing the BNC connector insulation.
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A knob swap won't help, and removing the 'insulation' (pretty looking plastic with no real purpose) does not create a safety issue.
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Stupid question #1:
Why do you need to keep connecting/disconnecting your probes? I connected two probes to my Siglent when I bought it two years ago and I haven't unplugged them since.
Is it because you're needing to use different probes or what?
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xrunner is right.
This oscilloscope can't be used with an unearthed mains. This isolation of BNC connector is useless.
Those probes are probably intended to be used with battery powered oscilloscopes.
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Those rubber are NOT for isolation, I guess its just for aesthetically purpose.
Both sides, either at the scope and probe BNC need to be fully protected and secured, not just wrapped with some cheap rubber that can easily be detached or cut.
Example below Tek's portable scope with isolated BNC connectors, and also at the probe's BNC for total isolation. The probe's head BNC metal part is fully molded with plastic, don't think can be easily detached like that cheap rubber without destroying the whole BNC head.
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I also cut my probed so they fit a Tektronix scope.
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Just don't float your scope.
Or it may end badly.
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xrunner is right.
This oscilloscope can't be used with an unearthed mains. This isolation of BNC connector is useless.
Those probes are probably intended to be used with battery powered oscilloscopes.
Check the safety instructions from the DS1054Z manual -
Page II
Ground the Instrument.
The instrument is grounded through the Protective Earth lead of the power cord. To avoid electric shock, it is essential to connect the earth terminal of the power cord to the Protective Earth terminal before connecting any inputs or outputs.
Connect the Probe Correctly.
If a probe is used, do not connect the ground lead to high voltage since it has the isobaric electric potential as ground.
Safety Class Class 1 – Grounded Product
Nowhere in the manual does it specifically state to use probes with "rubberized" coatings over the BNC connectors to satisfy any safety requirements.
So, as has been noted, any operation of the scope outside it's safety notices is done at your own personal risk.
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ds1000e probe is better ergonomically compared to the newer design ds1000z probe, this perharps another good example why you dont want the new kids on the block to design the so called "modern design". admittedly several times i got pissed off already with the slippery new ds1000z probe design. but i dont think a full circumcision is a good idea, see below for suggestion, ie cutting small part of the rubber to make groove or negative slope for you to grab on while pulling...
as far as the isolation is concerned, few days ago i got loose earth connection to my scope (DS1000Z) so i got the usual annoying tingling going on on the gnd pigtail, i said what the hell, i push all my main sockets in the line properly and the tingling is gone. this tingling sensation of "elevated gnd" is only sensible to my thinner skin such as back of my finger, lower back body etc, i dont feel it on my face front of my finger due to thick skin i guess, or if i grab the contact point firmly with significant amount of skin surface area (making big portion of me elevated as well i guess). the worst case of "elevated gnd" / isolated device scenario i remember was few years ago when i was handling a LCD projector in a ballroom, its a brand name not one hung low, things like epson if i'm not mistaken, but it can be samsung etc, cant really remember, but the point is, not a one hung low. it has 2 pin cable, ie unearthed, so i gave up and let anybody incharged handling it. i also got occasionally from things like tv, laptop, etc. so this isolation problem is real, to my belief, anything involving SMPS inside, not particularly a DSO, but it is included... so this matter probably wont matter to you if you have thick skin from back of your palm to the lower latissimus dorsi and external oblique..
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ds1000e probe is better ergonomically compared to the newer design ds1000z probe, this perharps another good example why you dont want the new kids on the block to design the so called "modern design". admittedly several times i got pissed off already with the slippery new ds1000z probe design. but i dont think a full circumcision is a good idea, see below for suggestion, ie cutting small part of the rubber to make groove or negative slope for you to grab on while pulling...
as far as the isolation is concerned, few days ago i got loose earth connection to my scope (DS1000Z) so i got the usual annoying tingling going on on the gnd pigtail, i said what the hell, i push all my main sockets in the line properly and the tingling is gone. this tingling sensation of "elevated gnd" is only sensible to my thinner skin such as back of my finger, lower back body etc, i dont feel it on my face front of my finger due to thick skin i guess, or if i grab the contact point firmly with significant amount of skin surface area (making big portion of me elevated as well i guess). the worst case of "elevated gnd" / isolated device scenario i remember was few years ago when i was handling a LCD projector in a ballroom, its a brand name not one hung low, things like epson if i'm not mistaken, but it can be samsung etc, cant really remember, but the point is, not a one hung low. it has 2 pin cable, ie unearthed, so i gave up and let anybody incharged handling it. i also got occasionally from things like tv, laptop, etc. so this isolation problem is real, to my belief, anything involving SMPS inside, not particularly a DSO, but it is included... so this matter probably wont matter to you if you have thick skin from back of your palm to the lower latissimus dorsi and external oblique..
This may be a stupid question, but what is the source of the elevated gnd when the mains ground is compromised? It certainly isn't a fault, right?. Is this an induced voltage? Does this imply there is always a current running to ground when the mains ground is properly connected? Thanks.
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who knows? someone should make a teardown study on this. probably there is capacitive coupling between power and chasis... but with a floating scope, once you connect the gnd clip to the hot line, there is no telling, no warning that the chasis is isobarically hot.
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Ah that's better! I hate those rubber rings with a passion.
Great idea. :clap: I hate those slippery connectors.
How hard was it to cut off the rubber?
Is the rubber stuck to the metal or just molded around it?
In your photo it looks like there is some residue on the BNC. Did the BNC come out clean?
I will cut mine off if it doesn't make a mess.
Thanks xrunner.
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It's plastic with an overmould, so it takes a good sharp knife, but it's not hard. Just moulded on, so cut a slot down it and pry it free.
E: Actually, I think they were just pushed on, but they'll probably resist being yanked off quite aggressively.
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Great idea. :clap: I hate those slippery connectors.
How hard was it to cut off the rubber? ...
Yes Monkeh answered your questions.
I wouldn't have bothered to cut them off if they had not been so slippery to remove. I have other cables (from China) that have coverings on the BNC and they are no problem at all to remove. Rigol simply picked a bad design IMHO.
In picture left = easy; right = hard.
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What's the problem with al that isolation issues? The Rigols are NEVER made and intended to probe mains levels like the portable Tek with full isolated channels. Doing so is simply stupid and that belongs to basic knowledge. This not only holds for the Rigols but any instrument not specially made for dealing mains voltages.
The probes that come with the Rigol scopes are at the $10 level you find on Ebay. They have to cut costs somewhere... That plastic boots are only cosmetic (and good to make a lot of noise about safety is seems).
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Great idea. :clap: I hate those slippery connectors.
How hard was it to cut off the rubber? ...
I wouldn't have bothered to cut them off if they had not been so slippery to remove.
Mine are so slippery I sometimes have to pull on the cable. I'll give the knife a try. :)
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ds1000e probe is better ergonomically compared to the newer design ds1000z probe, this perharps another good example why you dont want the new kids on the block to design the so called "modern design". admittedly several times i got pissed off already with the slippery new ds1000z probe design. but i dont think a full circumcision is a good idea, see below for suggestion, ie cutting small part of the rubber to make groove or negative slope for you to grab on while pulling...
as far as the isolation is concerned, few days ago i got loose earth connection to my scope (DS1000Z) so i got the usual annoying tingling going on on the gnd pigtail, i said what the hell, i push all my main sockets in the line properly and the tingling is gone. this tingling sensation of "elevated gnd" is only sensible to my thinner skin such as back of my finger, lower back body etc, i dont feel it on my face front of my finger due to thick skin i guess, or if i grab the contact point firmly with significant amount of skin surface area (making big portion of me elevated as well i guess). the worst case of "elevated gnd" / isolated device scenario i remember was few years ago when i was handling a LCD projector in a ballroom, its a brand name not one hung low, things like epson if i'm not mistaken, but it can be samsung etc, cant really remember, but the point is, not a one hung low. it has 2 pin cable, ie unearthed, so i gave up and let anybody incharged handling it. i also got occasionally from things like tv, laptop, etc. so this isolation problem is real, to my belief, anything involving SMPS inside, not particularly a DSO, but it is included... so this matter probably wont matter to you if you have thick skin from back of your palm to the lower latissimus dorsi and external oblique..
This may be a stupid question, but what is the source of the elevated gnd when the mains ground is compromised? It certainly isn't a fault, right?. Is this an induced voltage? Does this imply there is always a current running to ground when the mains ground is properly connected? Thanks.
I just ran across this document from Fluke which discusses "leakage current". I wasn't aware of this and it probably provides the answer to my own question. http://www.fluke.com/fluke/uses/comunidad/fluke-news-plus/articlecategories/electrical/leakagebasics (http://www.fluke.com/fluke/uses/comunidad/fluke-news-plus/articlecategories/electrical/leakagebasics)
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On a more serious note. Isn't it common to plug in a non insulated bnc tee, for example, to terminate into 50 Ohms? There will always be a potential issue if you defeat the grounding of the scope, no? As Mr. Carlson says, "you do so at your own risk".
Absolutely.
If the oscilloscope industry wanted to really protect people, they would do a complete connector solution, something like DMMs, where not only the internal but the external connections are completely insulated from the user. As it is now, you can still touch the same potential on other BNCs that one or more probe covers are insulating you from, as has been pointed out.
Do all of this testing and modification at your own risk!
If the oscilloscope industry wanted to really protect people... they would sell scopes, or probes and adapter units, that are fully galvanically isolated and appropriately tested/rated for a certain level of safety in these kinds of differential floating applications. Which of course they do sell.
If you work with a floating scope, then you need to know what you're doing, and it's not the manufacturer's responsibility to babysit you. The oscilloscope chassis, and every connector and port that is normally grounded, is floating relative to mains earth.
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On a more serious note. Isn't it common to plug in a non insulated bnc tee, for example, to terminate into 50 Ohms? There will always be a potential issue if you defeat the grounding of the scope, no? As Mr. Carlson says, "you do so at your own risk".
Absolutely.
If the oscilloscope industry wanted to really protect people, they would do a complete connector solution, something like DMMs, where not only the internal but the external connections are completely insulated from the user. As it is now, you can still touch the same potential on other BNCs that one or more probe covers are insulating you from, as has been pointed out.
Do all of this testing and modification at your own risk!
If the oscilloscope industry wanted to really protect people... they would sell scopes, or probes and adapter units, that are fully galvanically isolated and appropriately tested/rated for a certain level of safety in these kinds of differential floating applications. Which of course they do sell.
If you work with a floating scope, then you need to know what you're doing, and it's not the manufacturer's responsibility to babysit you. The oscilloscope chassis, and every connector and port that is normally grounded, is floating relative to mains earth.
Yup, for example my Philips PM3540 is floating by design. It doesn't even have ground pin on plug. If it had plug from one of countries where all plugs are 3-terminal, the only thing one could notice is that there's one line like "Hey, it's floating, because TV's, mon. Beware!" written in small print in the manual:)
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The moldings do look quite nice but are shaped rather poorly. The BNC jacks feel almost like they suction themselves onto the scope. I don't see removing the molding as any kind of safely issue on a scope with common probe grounds.
In the case of the Tektronix THS portable scopes pictured earlier in this thread then the shrouding is critical for safety and has nothing to do with aesthetics as it has isolated inputs.
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As a user of DS1000Z, I agree with comment about bad form factor of BNC mouldings. At first glance, they look OK and connect to scope very easily, but disconnection is definitely more difficult - connector tend to stick and your fingers cannot grip and generate enough pull to remove it in one go.
However, in my setup I do not reconnect probes too often for this to be an issue requiring mechanical intervention.
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Two good grip mods here. Thanks, I'll keep these in mind should mine annoy me. It's better to mod the inconsequential rubber jacket than to pull on the cables and shorten the probe's life.