Rigol DS1054z Failure, Error?

[reinhard_s]

Hallo,
my Englisch is not the best, but I try to explain my problem:

The Rigol DS1054z is new with the latest software!

The rigol ist connected directly to the power supply system.
All probe inputs are connected to GND
Trigger is set to "auto"
Channel 1 is on, measurement system is also on.
Time base is set to 10ns/div (changing time base has no effect)

I measure the following when time base (V/div)
is set to:

V/div                Vpp                 ca. Vrms

1 V                  40 mV             34 mV

5 V                  600 mV           215 mV

0,5 V               20 mV             15 mV

What I am measure seems a square wave with 8ns

The beam is not in the zero position and shows the same voltage as I measure with the measuring system.

Normally, when I put all probe inputs to the ground, the beam has the position in the middle of the screen and I measure zero voltage.

Can someone test this effect or explain it or is my Rigol wrong and I must send it back?

Thanks to all

Best regards
Reinhard

[electr_peter]

Hi,

I do not completely understood what you have written, but I would interpret your question as:
"I connect GND to probe tip and scope still shows some small voltage. Why is this happening? Why voltage shown is not zero?"

I think this is happening: scope is sampling at very fast timebase (10ns/div) and pick ups (from environment or from internal error sources in signal path) small error. This error is largely attributable to digitisation error/noise.
Remember than scope has 8 bits resolution (=256 different values, actually even less). Minimum resolution on 5V/div range is (5V * 8 vertical divisions) / 256 data points ~ 0.16V. Thus few bits up or down can create 600mV.
Math functions then just show statistics ("average" view of this noise).

I would consider such behaviour as normal. DS1054Z is known to have some offset on all channels depending on which are turned on/off. It is not an indication of error or fault in oscilloscope.

I suggest to remove "Poll" from this message, it adds no value.

[baoblackcoal]

noise is reasonable? especially in the low voltage.