Newbie Help with Probe Calibration on BK Precision 2160 - Page 1
Forum section: electronics / beginners

author: denimdragon
author_rank: Regular Contributor
timestamp: May 05, 2017, 04:49:52 am
content: First off, I want to say hello to everyone here. I've been lurking around here for a while and I have learned quite a bit. I'm hoping that someone can help me with my o-scope woahsI recently purchased a BK Precision 2160 (Not 2160A) for $50 bucks locally and for the last 3 days, I have been trying to make sure that everything is ok with it. I finally managed to figure out how to see a waveform from my BK 4011 Function Generator (also purchased from the same person). I was like a kid lol. Anyways, I am now trying to calibrate the probe (it came with a Tek P2220) with the CAL thingy, but I'm not getting anything except the straight trace across the CRT. From my limited understanding, I am suppose to connect the probe (without the ground lead attached) and it should produce a square waveform. I have the manuals but they don't say much except to connect it to the .2V P-P tab. I set the Volts/Div @ .2 and the Time/Div @ .2 mS and did some careful knob turning. I'm pretty green at all this so if I'm doing something really wrong, feel free to send me a virtual pimp slapI have watched a few videos on this and read up on it, but I think I am missing something. It would be awesome if someone could lend a hand. I'm a first year EE student so I need to master this. It's challenging enough to start another career at 43 without the added inability to work with the tools of the trade.I'm posting some pictures of what the scope is currently set @ and pictures of the CRT. I hope someone can help. Thanks in advance guys.

author: tautech
author_rank: Super Contributor
timestamp: May 05, 2017, 05:16:41 am
content: Welcome to the forum.Trigger and channel coupling to DC.IF it's a 10:1 probe the input attenuator (V/div) need be set to 10x or more, more sensitive, say 10mV/div.When you have a waveform, that may or may not scroll across the display you can stop it by adjusting the Trigger level pot when you should be able to see the point of amplitude (level) on the left side of the display from where the waveform originates. That's where the electron beam starts its sweep.All going well the waveform should be ~2 divisions high.

author: denimdragon
author_rank: Regular Contributor
timestamp: May 05, 2017, 10:05:52 pm
content: Hi tautech, Thanks for the information. I tried it and it still didn't work. So know I'm thinking that the probe is bad, but I read another one of your replies to another thread that said if the input capacitance of the scope doesn't match the compensation range of the probe, it won't work properly. I think this might be my issue. I'm posting some pics of the specs on the probes and the scope. Please let me know if my notion is correct or I'm barking up the wrong tree. Thanks again for your help

author: tautech
author_rank: Super Contributor
timestamp: May 05, 2017, 10:19:11 pm
content: Quote from: denimdragon on May 05, 2017, 10:05:52 pmNo, a probe with an insufficient compensation range will have no problem providing a signal to the scope and on the display, it's just you won't be able to properly adjust it for a perfectly square waveform.Just try a piece of wire for now and that will confirm if the probe is crook or not.You don't need anything flash for hobbyist probes, have a search on eBay or other online sellers for ones labeled/marked as P6100. You should be able to find them for $15/pair.

author: rdl
author_rank: Super Contributor
timestamp: May 05, 2017, 10:29:30 pm
content: How did you connect to see the output from the function generator? Use the same.Check the calibrate output. Maybe it doesn't work. Any multimeter should be able to read something there.

author: denimdragon
author_rank: Regular Contributor
timestamp: May 05, 2017, 11:17:52 pm
content: Hi rdl. That's exactly what happened. The CAL where the probe attaches to is wonky and wobbly (I'm assuming that it shouldn't be as loose as it is). I finally have a waveform but I had to wiggle it until I found a consistency. I did check it with my DMM but I had a brain fart somewhere.tautech, rdl, thanks so much for your help. I now can finish checking out the rest of the scope. I really want to master this because I have a few projects to work on (See pictures) to get my feet wet, plus I'll be needing it for school until I get my Rigol. You guys are "The Bees Knees"! Thanks again.

author: tautech
author_rank: Super Contributor
timestamp: May 05, 2017, 11:48:04 pm
content: Quote from: denimdragon on May 05, 2017, 11:17:52 pmAnother thing to fix.You can see from the image it appears to be a 10:1 probe but it still needs some compensation adjustment to square up the display, then you're good to go.Now you know what it should look like think of the probe Cal output as your first sanity check when you don't understand what's going on.Now the Cal output is anominal200mV p-p (this scope) @ 1KHz, notice the word nominal, they are very rarely exact but they serve the probe Cal purpose well.Take some time to get your head around probe divisions of which there are numerous, 1:1, 10:1 and 100:1 are the most common. As the division increasesnormallyso does the voltage rating of the probe, but reciprocal to the very important applied capacitance of the probe when applied to a DUT. Simply, all measurements in some way affect the actual measurement value in a DUT.For this reason use 10:1 probes for all your work unless you need the increased sensitivity a 1:1 probe provides but at the cost of increased capacitive loading on the DUT and lower voltage rating.When you get other probes, also study their graphs that show how voltage ratings diminish with frequency.Don't push probe and ch input ratings, err well on the side of caution for your own safety and that of your instrument.Have fun now you have new eyes to see what's happening.

author: denimdragon
author_rank: Regular Contributor
timestamp: May 06, 2017, 12:22:10 am
content: I will definitely be studying up on probes more. A craftsman can only be as good as his tools AND his ability to use those tools correctly. In my former career I was a CNC programmer/machinist, so I'm very picky about tolerances and metrology. I know the scopes main focus is for waveform study, but I want to know all the inconsistencies that arises in every step of the measuring process. The more components you add to a system the more room for deviations. Learning these things will help me when troubleshooting so I won't go down the rabbit hole looking for something that should be accredited to known deviations in my measuring equipment. I'm devoting the rest of my weekend to learning about this, and having a beer or 3

author: w2aew
author_rank: Super Contributor
timestamp: May 06, 2017, 12:41:52 am
content: Quote from: denimdragon on May 06, 2017, 12:22:10 amHere's an old video of mine, all about probes. Discusses compensation too.

author: denimdragon
author_rank: Regular Contributor
timestamp: May 06, 2017, 01:19:05 am
content: That's the video I'm currently watching Alan lol. I'm subbed to your channel

author: denimdragon
author_rank: Regular Contributor
timestamp: May 06, 2017, 04:12:13 am
content: I'm back with another question. Now that I have the CAL output situation solved, I thought all was well (and it could be. I'm sure my ignorance will come into play here), but now I'm getting these waveforms on the scope and the probe is just laying on my desk (wood). The settings are the same- V/Div 10mV, T/Div .1mS. I did adjust the probe to get a good straight square waveform at these settings and all was well. Maybe I invoked this when I adjusted the probeNow I'm curious as to what this may be. Any pros want to help me out? I pay in beerNote: When I remove the probe trace is flat again. Thanks again everyone for the guidance.

author: rdl
author_rank: Super Contributor
timestamp: May 06, 2017, 05:03:40 am
content: Oscilloscopes are also good radio receivers. The probes are the antenna. They can pick up all sorts of odd stuff.

author: tautech
author_rank: Super Contributor
timestamp: May 06, 2017, 06:27:28 am
content: Quote from: denimdragon on May 06, 2017, 04:12:13 amrdl nailed it.They can pick up all manner of muck, 60 Hz mains, SMPS EMI and general RFI............all of which you can use to some advantage.OK, let's say you have a walwart that you don't know if it's working or not or a similar part of a circuit with some high speed switching going on. Waft an unconnected probe past/close to it and watch the display. Remember this trick as a quick test for a power switching device's operation, sure it's only a yes or no but sometimes that's all you need.

author: denimdragon
author_rank: Regular Contributor
timestamp: May 06, 2017, 04:20:49 pm
content: I thought about the antenna effect as well, but I just wanted to be sure. So many little tricks of the trade early in the game. You guys are making me dangerous LOL. This is awesome news. Looks like my $50 was well spent.I checked the component tester on the scope and it's working as well. My next step is to check that both of the function generators I purchased are good. I used the BK 4011 to get my first sine wave on the scope. Checking them seems like it would be easy enough. I'm pretty good at researching and digging. If not I'll be right back at the forumThanks again guys!

author: w2aew
author_rank: Super Contributor
timestamp: May 08, 2017, 12:42:26 pm
content: Quote from: denimdragon on May 06, 2017, 04:20:49 pmWhen checking out your function generators, you may want to keep this in mind...

author: tggzzz
author_rank: Super Contributor
timestamp: May 08, 2017, 12:55:57 pm
content: Quote from: denimdragon on May 06, 2017, 12:22:10 amGood attitudeFor more info on probes, see the references inhttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/BTW, how are you measuring conductance (S, Siemens) on the scope? It is a lot easier to measure time (s, seconds)!

author: denimdragon
author_rank: Regular Contributor
timestamp: June 28, 2017, 10:08:25 pm
content: Quote from: tggzzz on May 08, 2017, 12:55:57 pm