DS1054Z not picking up mains hum. good or bad? - Page 1
Forum section: electronics / testgear

author: VoidsWarranties
author_rank: Contributor
timestamp: October 28, 2016, 07:08:37 pm
content: My oscilloscope does not pick up much of a 60Hz hum or noise instead it is 55.5khz. I do not know if I should treat this as a good thing or a bad thing, could this mean there is a problem with the scope?If it helps I do live quite close to a cell tower there are also some photos of the waves below.

author: Fungus
author_rank: Super Contributor
timestamp: October 28, 2016, 07:30:27 pm
content: Did you touch the probe with your finger?

author: metrologist
author_rank: Super Contributor
timestamp: October 28, 2016, 08:34:48 pm
content: why do your screenshots confuse me? Does it look like a hint of 60hz hum in the first?

author: VoidsWarranties
author_rank: Contributor
timestamp: October 28, 2016, 08:45:56 pm
content: I did try touching the probe. I should be asking what 55khz is fromSent from my iPhone using Tapatalk

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 28, 2016, 10:37:49 pm
content: One would certainly expect to see a pretty massive 60Hz hum if you touch the probe tip with a finger (ground clip not connected to anything.)Please set your scope up as shown in the screenshot below and post the image. Note that both the switch on the Probe, and the channel setting, are set to 10x, and the channel V/div is set to 10V/div and the input coupling is set to DC. Probe ground clip not connected to anything, touch tip of probe with finger. Horizontal timebase at 5 ms/div. (Your amplitude will probably be different but you should still see a clear mains hum.)

author: VoidsWarranties
author_rank: Contributor
timestamp: October 29, 2016, 12:26:42 am
content: I followed all of you steps and I can clearly see the 60Hz but is nowhere near a sine waveSorry it is not a screen shot from the scope itself, it is just a picture of the screen.Sent from my iPhone using Tapatalk

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: October 29, 2016, 12:44:53 am
content: perhaps? Seems like you have some source of EMI other than mains.

author: kfnight
author_rank: Regular Contributor
timestamp: October 29, 2016, 01:33:54 am
content: The 55 kHz is from the fluorescent lights. If you make your measurements in the dark that should go away.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 29, 2016, 01:58:28 am
content: Quote from: VoidsWarranties on October 29, 2016, 12:26:42 amI have CFLs, mains LED bulbs, UPS and other SMPS, wifi routers, cellphones etc. operating all around me and I still get a pretty clean mains hum as my screenshot above shows.Does it do this on all channels or just CH1? Does it do this with just the one probe, or do you see it with every probe and on every channel?Is your scope's mains power cord plugged into a UPS, or do you have a UPS or other heavy SMPS connected on the same mains circuit as your scope? Just grasping at straws here. It sure looks like you are picking up some heavy HF EMI as well as a very distorted 60Hz mains supply hum.

author: VoidsWarranties
author_rank: Contributor
timestamp: October 29, 2016, 02:05:20 am
content: I have checked all of the channels and probes but they are the same as channel one. I do not have anything that should change the wave that much. When I did my tests I only had a security camera dvr and my cfl bench lights, no inverter-type devices any where on any circuit.Sent from my iPhone using Tapatalk

author: VoidsWarranties
author_rank: Contributor
timestamp: October 29, 2016, 02:09:49 am
content: I just tested it with the lights off and I got a much better 60Hz sine wave. I did not expect them to make such a large differenceSent from my iPhone using Tapatalk