SDS1104X-E noisy waveform on built-in calibration pin - Page 1
Forum section: electronics / testgear

author: dredd
author_rank: Contributor
timestamp: July 14, 2021, 07:38:57 am
content: Don't kick me please, my first scope, got it a week agoIm doing probe calibration. 10X both probe and scope, 500mV/div (SDS00002.png) and I see noise on horizontal parts (Noise.png). Also, if I lower the trigger level down to 60mV (SDS00003.png), it looses sync lock, meaning noise is ~60mV, right?Question is, is this all as it should be, normal or I got a lemon?Also, startup time, from power button to waveform is 27 sec, a bit long or normal?Thanks!

author: tautech
author_rank: Super Contributor
timestamp: July 14, 2021, 07:49:59 am
content: Entirely normal because:#1&2 show SMPS noise probably from LED lighting.#3 Trigger level is too close to the low limit of the waveform. Press the trigger level encoder to set it to 50%.

author: dredd
author_rank: Contributor
timestamp: July 14, 2021, 07:55:58 am
content: (exhaling) Thanks a lot, mind is at peace nowAnd I just saw youtube review, guy said startup time 25 sec, like mine.

author: tautech
author_rank: Super Contributor
timestamp: July 14, 2021, 08:02:00 am
content: Triggering very near the lower amplitude of waveforms can be unstable due to trigger hysteresis and much more so than near the upper limit. As an example adjust the V/div to have the probe Cal signal ~0.2 of a div and experiment with levels to find stable triggering.Any EMI like from LED lighting further compounds this effect.Have fun learning your new scope.

author: Pfriemler
author_rank: Regular Contributor
timestamp: July 14, 2021, 09:44:33 am
content: Quote from: dredd on July 14, 2021, 07:55:58 amEnjoy the ~60 s a RIGOL MSO5xxx needs... my MigSic (same noise when measing the probe test signal) needs ~40s(and my old UNI-T UTD2042C 4s.)btw: is that probe a bit undercompensated?

author: radiolistener
author_rank: Super Contributor
timestamp: July 14, 2021, 10:14:47 am
content: It looks that you're forgot to connect ground pin to the probe, so all your probe, include 1 meter cable works like a large magnetic loop antenna to sucks in all the noise from your nearby equipment and mains wires.If the ground pin is connected, then it looks that you're connected ground pin with alligator clip on a wire. In such case your alligator clip with wire also works as a magnetic loop antenna, but more smaller and less sensitive.If you're want to avoid such noise, use special spring for the probe to eliminate antenna loops on your probe.Connect ground spring to the ground terminal and probe pin to the signal terminal of calibration output.With this spring the ground wire length is very small, so the loop will be small enough to avoid noise reception.

author: dredd
author_rank: Contributor
timestamp: July 14, 2021, 11:57:54 pm
content: ground pin was connected with alligator clip to scope's earth pin. Thanks for the spring pic, now I know how to use it

author: radiolistener
author_rank: Super Contributor
timestamp: July 15, 2021, 12:03:09 am
content: Quote from: dredd on July 14, 2021, 11:57:54 pmDoes it help you to reduce noise?Because there is also possible third reason for the noise, the noise can be really present on a calibration source terminals.

author: Pfriemler
author_rank: Regular Contributor
timestamp: July 15, 2021, 09:33:31 am
content: OMG. So that's what those funny springs in the bag were for. :-) The unusual large horizontal resolution (28M instead of 1k - yes, no joke!) also requires some rethinking for me with the new scope in recording usable signals. It is unbelievable what you can capture with one turn (crocodile clip of the short earth wire at the probe tip).Besides that, I found my test signal not noisier than that of my new RIGOL AWG or even any cheap rectangle output (DMM, comonent tester, ...). It's more about how recent scopes do pickup signals in principle, I think.