Oscilloscope Won't Set Properly - Page 1
Forum section: electronics / beginners

author: Adam60
author_rank: Regular Contributor
timestamp: February 20, 2016, 12:08:41 am
content: Hey all, I have a Circuit Test OS-2030 Scope and I am going through the calibration procedure with my probes and I can't get my square wave signal to sit still on the screen. I am on X10 and have all the settings where they say I should be, but when I move the VAR sweep (Horizontal), there is a very fine spot where I can almost get it to stop moving but even there it is jumping left-right-left etc. Am I doing something wrong? I have an old Phillips scope as well. Maybe I will see what it does.Any thoughts.

author: Skimask
author_rank: Super Contributor
timestamp: February 20, 2016, 12:12:44 am
content: A thousand videos out there on how to properly use an oscope. Suggest you watch one or fifty of them. Something willtriggeryour thoughts to the solution.

author: Adam60
author_rank: Regular Contributor
timestamp: February 20, 2016, 12:18:45 am
content: Have watched several already. Scopes new to me. The one I watched in particular, the square wave signal sat nice right in the center of the screen and didn't move. Not registering with this brain. I do a lot of research before I ask a question on here and only when I am absolutely stumped, do I post. I do that because people will tell you to go read or watch a video instead of offering up a true solution, perhaps because it is easier, or perhaps because they don't know the real answer. Thank you for your time though, I do appreciate it.

author: Skimask
author_rank: Super Contributor
timestamp: February 20, 2016, 01:37:33 am
content: Didn't happen to see any bold letters around here, did you?How about throwing up a GOOD quality picture ofyourfront panel?Maybe just the picture can help a guy figure out which setting you don't have right.

author: tino_so
author_rank: Contributor
timestamp: February 20, 2016, 02:20:00 am
content: As Skimask noted, the issue is most likely relate to your triggering settings. Remember to set the triggering to the channel you are using to calibrate your probe, it is a easy mistake one can make.Also mind the other settings around your trigger controls. A quick search on Google did not turn up a manual for this scope. Would you have a pdf you can share? Otherwise as Skimask also suggested, a clear photo of the front panel should be the next best thing to get an idea of what your dealing with.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 20, 2016, 02:39:53 am
content: Quote from: Adam60 on February 20, 2016, 12:18:45 amThere may be other reasons as well. Sometimes I wonder why very experienced people even look at theBeginner's Thread.To address your problem... and maybe spoil somebody else's fun ... have you varied the setting of the Trigger Level control to see if that will stabilize the display of your square wave?

author: ElectronSpinner
author_rank: Newbie
timestamp: February 20, 2016, 03:09:19 am
content: Set the varistor all the way clockwise until it clicks, there it is in calibration and it should not drift. Also make sure your mode is in DC at the proper channel 1,2 etc

author: Adam60
author_rank: Regular Contributor
timestamp: February 20, 2016, 04:52:42 am
content: First off, I would like to address Skimask and his comments. I am guessing from reading some of your posts that you are fairly intelligent when it comes to electronics and everyone on this forum is beneath you. Your sarcasm indicates that and I just want to remind you that this is a beginners forum, as someone else pointed out. My question is, why are you here. I can only think of two reasons. The first one is that you feel better about yourself by belittling the people on here that don't know as much about electronics as you do. The second one is that perhaps you are here to learn as well but good to throw a jab into those of us that don't know so much. I want to remind you what a forum is in case you weren't sure. It is a place where people of all ages and experience go to share information and knowledge, whether passing it along or absorbing it for their own consumption. It is a place to learn and when you open your mouth for no apparent reason, there is nothing to learn and nothing to share, so best left silent. If I am wrong about you I apologize but I have been a teacher for a long time and I recognize the tone. I feel sorry for sarcastic people. I used to be that person and it gets you nowhere. Enough said. If you can help, I would appreciate it and perhaps we can move past this. If not, have a nice day.As for alsetalokin4017 and ElectronSpinner, I thank you for your time and your comments. I did try as you said with no luck. I have included a couple of shots which I hope are clear enough for you to see. I had set the unit up as it was in the book and I could get a square wave pattern with the appropriate divisions to stop, but when I brought it down to a single wave, it was very sensitive and just wanted to roll either way, but never stationary. Perhaps on calibration I am not supposed to be able to do that? I am not sure. Perhaps someone can help. Just learning

author: jancumps
author_rank: Unknown
timestamp: February 20, 2016, 05:41:39 am
content: Does the 'var sweep' button have a locked position?Can you also try to play with the 3rd button on the top, 'trig'

author: Skimask
author_rank: Super Contributor
timestamp: February 20, 2016, 05:53:51 am
content: Quote from: Adam60 on February 20, 2016, 04:52:42 amYay!!! Grow a pair...either balls or ovaries, whatever the case may be. And fill out one of these:http://www.funnyjunk.com/funny_pictures/1553678/The/I'm happy you've been a teacher.Those who can, do. Those who can't, teach.The wave rolls left or right because it's not being 'triggered'. It's being swept at various times...sometimes slightly faster than the input signal (rolls left), sometimes slightly slower than the input signal (rolls right). If the 'scope is 'triggering' on an input wave, it wouldn't start sweeping until the input signal went above or below a certain setpoint. But you'd know that if you really read and listened to some of those o'scope videos.Is your probe connected to Ch1 or Ch2? Assuming Ch1, but the pictures shows a probe on both. Is it an X1 or X10 probe?Set trigger coupling to AUTO, Ch1, center the trigger knob, holdoff knob to zero.Channel 1, set to 1v/division, temporarily put coupling to GND and center the sweep (or move it a couple graticules down, whatever works), then put coupling back to DC. Make sure the VAR knob is pushed in or all the way towards CAL'D.Also assuming the CAL signal is 1Khz. Set time/div to 10ms, Var Sweep to zero or CAL'D. When you see a bunch of waves, set it back to 1ms.Slowly adjust the trigger towards + slope until you get a stable signal. There should be a fairly wide range of trigger setting to get a stable waveform on the screen.If that doesn't work, try the other probe, the other channel, an external signal source. If none of that works, probably got a bad 'scope.

author: Adam60
author_rank: Regular Contributor
timestamp: February 20, 2016, 06:53:57 am
content: Jancumps, the VAR sweep does not have a locked position. Have not tried the Trig button yet.Skimask, there is hope for you but I must say, there is a teacher in all of us as you have demonstrated. This is not my trade, just a hobby and in my trade I can do, and I can teach and I do it without making people feel small. I do have a pair and I don't have to flaunt them, some do as you have also demonstrated.In any case, I thank you for sharing your knowledge of scopes with me and I will try everything you have said in the hopes that someday I may be as proficient as you but I highly doubt it. I will post back what my findings are. The probes are X1/X10 and are also made by Circuit Test. The unit was just given to me so I was just trying to get it working so that I can play around with it and perhaps watch several hundred videos and get an idea of how it works. It seems I am wrong in asking questions on a forum

author: jancumps
author_rank: Unknown
timestamp: February 20, 2016, 07:06:04 am
content: The trig knob should do the trick. I see that you display channel1 and trigger on that same channel.(And place the variable sweep button in its CAL position for normal operation)

author: rdl
author_rank: Super Contributor
timestamp: February 20, 2016, 07:08:24 am
content: You need to try adjusting the knob marked "Trig". Set it so that it's somewhere between the upper and lower limits of the waveform.

author: Skimask
author_rank: Super Contributor
timestamp: February 20, 2016, 08:02:14 am
content: Quote from: Adam60 on February 20, 2016, 06:53:57 amLook again at the second post. See anything thatSTANDS OUT?

author: tautech
author_rank: Super Contributor
timestamp: February 20, 2016, 08:32:18 am
content: Quote from: Skimask on February 20, 2016, 08:02:14 am+1Sometimes the best teacher is the one that only helps you work things out for yourself.

author: Adam60
author_rank: Regular Contributor
timestamp: February 20, 2016, 05:52:53 pm
content: Okay so I have set the TRIGGER button and have the single square wave isolated on the screen. Thanks to all of you who helped, even the sarcastic oneNow that I have this signal here, it jumps up and down randomly and looks like there is "noise" on the signal. Should I be concerned or is this as good as it gets because it is a lower end scope? I am going to try this on my Phillips scope as well and see how it turns out. Thank you for the help. Skimask, you and I are going to get along just fine

author: tautech
author_rank: Super Contributor
timestamp: February 20, 2016, 06:03:40 pm
content: Quote from: Adam60 on February 20, 2016, 05:52:53 pmMy money is on dirty contacts of the V/div selector or possibly a switch in the signal path.Sometimes "exercise" of the switches can solve the problem.Most have gold plated contacts and must be cleaned with care.Deoxit and paper strips are the preferred methods.

author: Adam60
author_rank: Regular Contributor
timestamp: February 20, 2016, 06:48:06 pm
content: Thank you Tautech. I will give that a try and see what happens. The unit has been sitting around in a shop for a couple of years now so it may just be dirty contacts. Cheers!

author: Skimask
author_rank: Super Contributor
timestamp: February 20, 2016, 08:51:57 pm
content: Drop a video of it jumping around on youtube.Chances are more than a few of us around here would immediately recognize the symptoms.