RIGOL DS1054 : bug or am I doing it wrong? - Page 1
Forum section: electronics / beginners

author: CircuitBurger
author_rank: Newbie
timestamp: October 22, 2023, 06:36:05 am
content: Hello All,Thank you so much for the opportunity to post on the forum. I hope this is not too beginner of a beginner question.Here is a video showing the setup:https://www.dropbox.com/scl/fi/6zphopp8nucusukvxug8t/Rigol_Bug_Or_JustMe.mp4?rlkey=c9phuqjcv8z91m1wxun6ge9nu&dl=0* I am using a Rigol DS1054Z connected directly to a stabilized power supply. No probe is used, just direct connection.* On the attached video, you will see the power supply delivers 2V DC, and the Rigol is set for 2V per division, and the probe menu at 1X.* Yet on the screen, the vertical line doesn't line up with the first division, but around 0.5 div* When switching to 1V/div, and the power supply still at 2V, instead of seeing a line at 2 divisions, it is at about 1.6div...The symptoms are the same even if I add a load on the power supply (2V filament light for example).Am I doing something wrong, or do I have a buggy oscilloscope?Thanks a lot in advance for any pointers you can provide!

author: ataradov
author_rank: Super Contributor
timestamp: October 22, 2023, 07:06:12 am
content: Does it show the same with the 1x probe? It may be either scope calibration that is off, or dodgy wires or BNC adapter.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 22, 2023, 09:19:40 am
content: Have you measured the power supply with an external DMM in parallel with the oscilloscope?My guess is that the power supply does not really output the expected 2V. Could be a defective oscilloscope as well.

author: ataradov
author_rank: Super Contributor
timestamp: October 22, 2023, 03:12:23 pm
content: The video does show the multimeter. I agree though, a video is no the best way to convey information.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 22, 2023, 03:41:36 pm
content: Doh, the video didn't autoplay, so I thought the link was just a picture, sorry.The multiplication factor setting from the oscilloscope panel does not change the trace position. It only adjust the numbers and the on-screen voltage measurements. Those are for you to manually adjust 1x or 10x (DS1054Z does not have probe auto-detection), such that the probe divider switch will corresponds to the oscilloscope setting, so you won't have to multiply or divide numbers in your head. The scope will do that for you, but you must tell the oscilloscope the settings of your probe.For the stock DS1054 probes, it can only be 1x or 10x (there is a small switch on the probe). Since you plugged direct wires, that means you must set 1x from the oscilloscope.Now, about the lower than 2V value, before anything else, try a DS1054 self-calibration:- disconnect all probes, connectors and wires from the oscilloscope side- let it run idle for 30 minutes, to achieve thermal regime- Press 'Utility', then 'Down arrow' (on the right side of the display), then press 'Self-Cal'- let it finish the self-calibration (it may take 10-15 minutes)When the calibration finished message pops up on the screen, restart the oscilloscope.Just to make sure it is nothing wrong with the power supply and the ground (maybe the source is not a floating power supply), try a similar test with the wires connected to a battery. The DMM and the oscilloscope should indicate the same voltage.

author: ataradov
author_rank: Super Contributor
timestamp: October 22, 2023, 03:44:20 pm
content: For me there was only sound on the dropbox site, so I had to download it and play locally. Dropbox web interface sucks.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: October 22, 2023, 07:02:35 pm
content: Friend, do you have that error on all channels, or only on one??

author: Swake
author_rank: Frequent Contributor
timestamp: October 22, 2023, 08:03:41 pm
content: That scope should really show 2 volts.After calibration and changing channels, try this at different voltages and also add a measurement in the scope.

author: CircuitBurger
author_rank: Newbie
timestamp: October 23, 2023, 02:36:56 am
content: Thank you so much RoGeorge, this was it.I had done a calibration before checking, but immediately after turning on the scope.I did as you stated and waited actually a full hour, then did the calibration. The line is now showing "much closer" to the 2V division; and same when increasing the voltage to 8 or 10V.The line is strangely very thick (i'm used to the fine and accurate one of the old-style phosphorous screen scope I was using 20 years ago), but at least it's now within 1 millimeter of where it's supposed to be!Thanks again!!!

author: ataradov
author_rank: Super Contributor
timestamp: October 23, 2023, 02:39:21 am
content: Quote from: CircuitBurger on October 23, 2023, 02:36:56 amYour old scope could not show you full noise content of the signal. This is a very common misconception among people that prefer analog scopes. Ignorance is bliss, I guess.You can enable 20 MHz bandwidth limit and it should get you "cleaner" trace.