Do you keep your scope probes connected all the time? - Page 1
Forum section: electronics / testgear

author: dadler
author_rank: Unknown
timestamp: May 01, 2015, 01:55:15 am
content: Just wondering what the common practice is.My gut tells me that after a number of connect-disconnect cycles, the BNC connectors on scopes will wear and the some degradation will occur. I'm sure the connectors are rated for a certain number of cycles.So I generally keep them connected all of the time. This works fine, except I have two cats that love to chew on cords.I know Dave's solution to this (cat) problem would involve two large paper bags and a vehicle in drive--but I was wondering what everyone does. Do you leave your scope/DMM/etc probes connected most of the time?

author: Vgkid
author_rank: Super Contributor
timestamp: May 01, 2015, 02:08:05 am
content: I unplug mine. If the cheap chinese probes can survive semester after semester, years on end. Then you should be good. The only parts on probes that seem to die are switches, and broken probe tips

author: bithead9
author_rank: Contributor
timestamp: May 01, 2015, 02:11:55 am
content: I keep mine plugged in most of the time.

author: pickle9000
author_rank: Super Contributor
timestamp: May 01, 2015, 03:42:23 am
content: My lazy factor is high, always plugged in.

author: ivan747
author_rank: Super Contributor
timestamp: May 01, 2015, 03:44:50 am
content: I disconnect them because I store the scope in its bag so it doesn't rust in my area's weather.As for the cat problem, get him a chew toy, an already broken thing he loves to chew on, and get it near the oscilloscope probes. Now every time the cat gets in chewy mood, just yell at him if he chews on the cord, but ignore him if he chews on the chew toy. Works fine for meAt least when I watch himThe cat usually enters chewy mood when I am around and when he's on purr mode, I don't know how yours behaves. I don't get broken cables anymore.

author: pickle9000
author_rank: Super Contributor
timestamp: May 01, 2015, 03:51:43 am
content: A little Habanero juice on the probe cable will keep the cat off.

author: TiN
author_rank: Super Contributor
timestamp: May 01, 2015, 03:55:28 am
content: Lol @ cat problem (I don't have one). Could be expensive chewing experience if one have high-speed probesHaving P7380 probes in their bags disconnected usually, use them only when needed (which is rare),while more general purpose probes P6245's connected to scope all time.Logic analyzer P6810 connected at all times at frame, while others store in box (rarely use).

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 01, 2015, 04:16:36 am
content: BNC connectors aren't all that fragile.OTOH, leaving the weight of the probe cable pulling against the strain-relief is certainly more stressful, and more likely to cause premature failure, IMHO.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 01, 2015, 04:30:44 am
content: I don't think I've had a BNC wear out -- though I have discovered a few of my tees or terminators with bum inner grounds...I have had probes die though. Those Chinese ones seem to last about a year before the inner conductor frays and goes intermittent. Taking it on and off all the time would make that worse.Tim

author: rx8pilot
author_rank: Super Contributor
timestamp: May 01, 2015, 05:31:33 am
content: I will more likely damage the cable or the tip before the BNC has an issue. I also have $500 - $2000 probes that need to be cares for. I keep them in small Pelican cases until they are needed.

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 01, 2015, 07:02:27 am
content: I use cheap Wittig probes that cost $10 a set for 100MHz. At this price they are disposable so I tend to unplug them and chuck them in a large sandwich box in a drawer when done. Parasitic capacitance isn't great on these but I've learned to probe after any buffering rather than load the actual circuit I'm looking at if its sensitive.To be honest I worry more about the BNC connectors on the scopes myself as they are universally complete bastards to replace. My cheap goldstar scope has a rather loose channel 2 to fix on the TODO list.

author: pascal_sweden
author_rank: Super Contributor
timestamp: May 01, 2015, 07:39:54 am
content: Quote from: dadler on May 01, 2015, 01:55:15 amWhat about putting an extra BNC plug on the BNC connectors of the scope, and remove the probe from the extra BNC plug? This way the extra plug might wear out, but not the BNC connectors on your scope. The frequency of removing the extra BNC plug (when it actually would wear out) is much lower than the frequency of removing the probe from the extra BNC plug. Several years versus daily.

author: rob77
author_rank: Super Contributor
timestamp: May 01, 2015, 07:45:01 am
content: probes plugged in all the time on my bench scope and disconnect the probes after use for my handheld scope.also got a cable chewing cat - but the cat is banned from my "lab"

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2015, 08:03:19 am
content: Quote from: smjcuk on May 01, 2015, 07:02:27 amYou are quite right to be concerned for the BNC sockets, other than the electrical integrity the have to handle a lot of physical stress over their life.Quote from: pascal_sweden on May 01, 2015, 07:39:54 amIMO you'd need to check the manner in which the BNC's are secured first. Some only had a 2 lug socket soldered to the PCB and were prone to breaking one or both those lugs off. Depending on the scope's PCB you might have a good ground plane in which to strap the sockets to for better physical strength.Early Tek DSO's were bad for this.I'm always anxious with any probe with a large compensation/termination box because of the physical stress on the BNC.

author: daddario
author_rank: Regular Contributor
timestamp: May 01, 2015, 08:21:52 am
content: I only remove probes when I need to connect something else - otherwise it'd be silly as I use my scope effectively every single day. I generally also avoid unnecessary cycling of multimeter probes as no connector is eternal - yes, I've had to change sockets even on Flukes. I tend to keep one go-to meter with my favourite TL175 probes connected, while always unplugging all straight banana connectors from handheld DMM's after a job is done as I am a bit paranoid about something falling from the shelves and right upon them. When carrying equipment around, all cables get unplugged(including multimeter probes) and wrapped in a nice over-under method, like all the rest of the cables.

author: SeanB
author_rank: Super Contributor
timestamp: May 01, 2015, 08:29:10 am
content: Extension units, or adaptors for various connectors. I have a few fused probe protectors, designed to both do connector interfacing and to provide protection for the input using a small in line fuse in the body. Originally they were common on spectrum analysers as an accident with the press of transmit will blow the SA fast, but these with a 50mA fuse help protect against that, or at least the blown fuse will tell you the SA is now cooked.

author: rollatorwieltje
author_rank: Unknown
timestamp: May 01, 2015, 08:40:15 am
content: I usually leave mine connected, but really I'm not too worried about the BNC jacks themselves. I've only had plugs fail, the jack is usually fine (unless it completely rips off the board, the great days of coax ethernet).I'm more worried about the USB connector. So little mechanical support...

author: ivan747
author_rank: Super Contributor
timestamp: May 01, 2015, 11:23:24 am
content: Quote from: rollatorwieltje on May 01, 2015, 08:40:15 amWhile on that topic, let's talk about SMD 3.5mm auxiliary ports on cars

author: pascal_sweden
author_rank: Super Contributor
timestamp: May 01, 2015, 11:30:30 am
content: On some phones or tablets, there is plenty of room to use a mini USB connector.Still the manufacturers only use micro USB connectors. These connectors are so sensitive that you really have to be careful every time you insert the cable. But maybe it is part of their planned obsolence strategy?

author: rsjsouza
author_rank: Super Contributor
timestamp: May 01, 2015, 11:45:52 am
content: Since ages ago when I worked on the university lab, I have remove the cables after a day's work as the danger of inavertently yanking the cables laying around on the bench (and some folks even left them hanging past the bench sides!) was pretty high.Quote from: pascal_sweden on May 01, 2015, 11:30:30 amBelieve it or not, micro USB connectors allow a higher number of insertions than mini USB. In my experience I have seen a larger share of mini USB connectors damaged due to several reasons (bent pins, foreign objects inside, etc)

author: Fungus
author_rank: Super Contributor
timestamp: May 01, 2015, 01:00:20 pm
content: Quote from: rsjsouza on May 01, 2015, 11:45:52 amAnd the mini ones allow a higher number of insertions than the big chunky ones.http://en.wikipedia.org/wiki/USB#DurabilityPlus the micro connectors are designed to break the cable, not the socket. Cables are easy to replace.

author: German_EE
author_rank: Super Contributor
timestamp: May 01, 2015, 01:54:24 pm
content: One of my cats sometimes chews mains cables, he likes to live dangerously.

author: MarkL
author_rank: Unknown
timestamp: May 01, 2015, 02:17:16 pm
content: I keep them connected all the time and I hang them on probe holders on the side of the rack to keep them out of the way and the full weight of the cable off the probe and compensation box. It's very convenient to grab one and start measuring. I keep the hat on the probes to prevent being stabbed by the tips.The holder is Tektronix 352-0351-00. Each one holds 2 probes and was included in the accessories bag with P6131 probes I bought years ago.Those are Agilent probes in the picture.

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 01, 2015, 02:58:30 pm
content: Quote from: German_EE on May 01, 2015, 01:54:24 pmMy uncle was killed in a house fire caused by a dog chewing a cable (so the fire forensics people reckon based on the fact it was welded to the cable face first). I'd get rid of the cat. Poisonous dust, parasites, pissing on your data sheet folders (this happened when I had a cat) and leaving dead things around the house. Yuck no more. fuzzy death machines.

author: cdev
author_rank: Super Contributor
timestamp: May 01, 2015, 03:05:51 pm
content: If you live in an area with cold winters, you should avoid hanging anything which might get rusty or corroded on your outside walls, always hang cables and place electronics that needs to be functional on an interior wall. The reason can easily be shown in cold weather with a humidity sensor. There is a microclimate/boundary layer along walls where the temperature can be substantially lower and the humidity can easily go up 10 percentage points or more.The same thing goes for storage. This can be reduced by circulating the air, ideally (*after* doing a good initial cleaning!) using an air cleaning device.

author: SeanB
author_rank: Super Contributor
timestamp: May 01, 2015, 03:24:02 pm
content: Quote from: smjcuk on May 01, 2015, 02:58:30 pmMy sister's Canis Africanus also liked to chew on cables. She got up one morning, and had left a lamp out the previous night for the braai. Goes outside and the cable is gone, with only the small piece that was just short of the window left. The cable was still live, the dog had chewed off the cable, leaving small 5cm long pieces all over the back yard. Same with the car wiring, he ate the indicators off along with the lamps. eventually she got him an old tyre to chew on, rather than eating plastic cabling and such. Lovely dog, literally a quarry special, as he came from the brick quarry.

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2015, 07:59:20 pm
content: Quote from: MarkL on May 01, 2015, 02:17:16 pmNice, and soooo simple.I'll make something just like that out of a piece if alloy angle section.

author: ivan747
author_rank: Super Contributor
timestamp: May 01, 2015, 08:55:25 pm
content: Quote from: German_EE on May 01, 2015, 01:54:24 pmThe day he gets an electrocal shock he will never do it again. Hopefully he'll be alive

author: bitwelder
author_rank: Super Contributor
timestamp: May 02, 2015, 07:42:30 am
content: Darwin Awards 2011 Calendar: Miss Marchhttps://s-media-cache-ak0.pinimg.com/736x/bd/6f/29/bd6f291f10f89aa68caa610fe0a55bc5.jpg

author: Howardlong
author_rank: Super Contributor
timestamp: May 02, 2015, 09:33:10 am
content: OP: I leave them connected unless the scope's packed away in which case I remove them and store appropriately coiled up in the original transparent probe bags. I leave them on mostly through laziness, but also I don't want to unnecessarily cycle the BNCs. I'm the only one in the lab anyway, apart from the cat, who prefers chewing through iPhone headset cables to scope probes anyway.Quote from: MarkL on May 01, 2015, 02:17:16 pmNice. So nice, I just made my own from slotted trunking in about five minutes.Get some narrow slot trunking 25mm W, 40mm H, with narrow slots at 10mm intervals, cost £2.41 for 2m( eg ABB 05143:http://www.edwardes.co.uk/en/products/abb-05143-w-25mm-x-h-40mm-grey-4-6mm-narrow-slotted-panel-trunking-2m-length)Cut to length, snap off alternate fingers (they snap off very easily by hand), and mount.

author: kakureru
author_rank: Contributor
timestamp: May 02, 2015, 06:54:17 pm
content: I set out trap cables for the cats connected to a small voltage divider that puts out like 1000v @ a minisqueal of mah. (its more like the feeling you get with carpet static shock)Does not "hurt" the cat but makes them think twice about chewing random wires.

author: mushroom
author_rank: Regular Contributor
timestamp: May 03, 2015, 05:15:00 pm
content: "Do you keep your scope probes connected all the time?"No !Disconnecting them makes components a lot easier to store. (and requires less probes)

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 04, 2015, 08:19:57 am
content: Ha very funny

author: Dave Turner
author_rank: Frequent Contributor
timestamp: May 04, 2015, 09:25:43 pm
content: Never mind my scope probes' which I tend to leave connected - if my cats want attention they'll pull components out of my breadboards, but only if I'm watching them.On the other hand a friend of mine had a house rabbit (came in through the cat flap to curl up with the cat in front of the coal fire) who had a predilection for biting through the telephone cable. He clearly got a buzz from the mild electric shock.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 06, 2015, 07:23:28 am
content: Not possible to keep one set of probes on the scope. Often no probes are used, direct coax connection or BNC connectors come off the DUT direct into the input BNCs. There are a variety of other probes used from active probes to current probe & current probe amplifiers and more. 10x or 1x scope probes are used maybe 30% of the time, the remainder is varied. This does not include swapping plug ins which always results in BNC connector cycling.All these decades of inout BNC connector swapping as yet to cause a wore-out BNC connector on the Tektronix analog scopes, portable or plug in. Thinking about that, wore out BNC on high quality test gear appears to be very rare.Bernice

author: Howardlong
author_rank: Super Contributor
timestamp: May 06, 2015, 08:17:53 am
content: Although as mentioned earlier I generally leave the probes connected if the scope's on the bench, on MSOs I only connect the pods when needed because I don't use them that often, and they tend to get tangled up with other stiff too easily.Usually the standard passive probes are good enough for what I do, but occasionally I'll use a Z0 or active probe depending on what I'm doing, but not frequently enough to warrant spending time pulling the standard pasive probes out when I'm done for the day.