Large Offset on Rigol DS1054Z - all channels

[skua47]

Hi,
I am seeing large offsets in the data collected on my DS1054Z (SN: DS1ZA163554597).
The table below shows the offsets in the data. I used the average math function on the scope to calculate the offset.
Note that the POS dial is set to 0, except for the smallest range. Changing the POS value makes no difference in the offset and turning the AC coupling does not affect the observed offset.  I checked with another scope and with a multimeter, the function generator does not account for the offset.

The attached graph shows the result when the same input is presented to both CH1 and CH2. As you can see, both channels have the offset, but the offset on Channel 1 is most severe.

Is there a procedure to calibrate the scope inputs or does the scope require repair? What can you suggest to correct this issue.
   
                                                   Offset (mV)
Range (V/div)   Channel 1   Channel 2   Channel 3   Channel 4
10                   875                        630               1001                   780
5                   980                        379               654                   540
2                   940                        379               399                   160
1                   1010                     391              367                   184
0.5                   1040                    370              390                   160
0.2                   17                       82              13                           19
0.1                   19.3                      16                      8 .6                   11
0.05                   17.7                      9                      6                            5
0.02                   20                     7.7                    7.3                          4
0.01                   20.4                      8                    7.8                          4
0.005          20.8                     7.7                    7.7                          3.3
0.002          20.8                     7.6                    7.7                         3.1
0.001          20.5                     7.6                    7.8                         3.1
            
Small shift in offset with BW limit on or off - These are for BW limit off
1X probe, normal mode         

Thanks.
David

[ataradov]

There is internal calibration procedure that you can run from the menus. If that does no help, then there is not much you can do.

[Fungus]

Is there a procedure to calibrate the scope inputs

Yes.

Read the manual.

[skua47]

Thank

You


Very


Much!

[skua47]

Thanks,
 I finally found the procedure listed in the manual. The calibration seemed to work. I am really surprised though and how far out the offset was. 1 V seems entirely unacceptable for a commercial instrument.

[skua47]

Hi All,

I did the calibration (difficult to find menu item) and all seems well now. I think the fact that the offset was so extreme made me consider a hardware fault. Anyway a lesson to regularly run the calibration function on this scope.

Thanks