Rigol 2000 series sensitive to mains noise / capturing noise with out probes.

[Kiriakos GR]

I have just find a fresh video on Youtube from a Greek who is using one fresh DS2072, and he made complains that the scope are showing small spikes at the floor noise level in some hours of the day, even with out any probe connected.

Further investigation showed, that by moving the scope in to another house which is powered from another Mains circuitry (by the local power company), shown no problems at all.


The truth is that some problems it can be understood only by electricians "dear friends electronic repair mans".
Usually in such problems, the first think that you become suspicious about, is the quality of the earth wiring in your home or workshop.

And this earth-check needs the hand of an electrician, and naturally special test tools.

Basically no one told us up front, that by injecting unclear solar energy it to a well monitored and stable AC Mains grid, that this action deteriorates the quality of it.

The one though brings the next one, and the first conclusion could be that it is possible some very sensitive measuring equipment to be negative influenced when they get powered by deteriorated AC mains.  (Loaded with noise base frequency 60Hz) 

This story by it self is possibly the first proof that by getting a battery powered scope,
You are living behind the possibility to get in to the same problems like the ones that our Greek friend is facing.

Even so I am a bit worry about the bench top oscilloscopes, as I do plan to get a similar one, and probably the 100MHz one or higher than that.

Another user has witnessed the same issues by using a Voltcraft DSO-8104 (though probably a relabeled GW Instek GDS-2104).
His report speaks about:
a)   Lots of junk visible with a 100Hz period.
b)   The big dirty band has really a lot of tiny spikes, with some ringing.

Alternative tests with old Philips scopes and Hameg, showed zero interference to them.

By combining all the bits and pieces of the above story it seems that we have to slightly worry about two factors.
The first could be the power quality in our Mains 220V, and how stable and clear from harmonics are our 60Hz.
And about the second which is and the trickier, is the quality of the PSU which lives in our new scope.

I am not an oscilloscopes Guru and I have nothing to teach to anyone about them,
even so it is my obligation to offer few bits of extra awareness on the subject as electrician.

The AC mains filtering it were in the past decade one issue that was bothering mostly small telephone center which was installed in small hotels in the country side.
And I do have even a spare filter of those in my possession, but I have never though that it is possible my next oscilloscope to need it ?!