A couple of weeks ago I bought this model from Amazon and recently discovered an issue with Channel 2's waveform, (noise), jumping high by about 5 mV. Set the time base to a fairly quick 1 uSec or so for a fast sweep. With both probes disconnected, enable Channel 1 and set to about a 1 volt/div. Hit the Channel 1 "zero" to see that the signal is coincidental with the horizontial axis. Now enable Channel 2 and set to a low, (10-20 mV div) to better see the issue. Then with ANY channel 1 volts adjustment or hitting the Channel 1 "zero" button, see if the Channel 2 display jumps up - positive by abut 5 mV or so. see pix. Then if you turn off Channel 2 and then turn on again, the Channel 2 sweep will "reset" itself back to a true zero reference with the horizontal axis. (After hiting the Channel 2 "zero" button, the signal still stay high).... Rigol support said they could not duplicate the issue, (I'm skeptical).... and instead of exchanging for a new unit from Amazon, I FOOLISHLY spent 56 damn bucks to sent to them for "repair". IF I had known the FL to OR shipping would be this high, I would have/should have made the exchange. The pix illustrate the issue and I'll appreciate any feedback from users of this model line of scopes.... Thanks for your replies...

 

Time to engage that stuff between your ears.....Ch 2 scope setting is at 10mV/div but for a 10x probe.....in other words Ch 2 is set for max sensitivity......1 mV/div.
In most DSO's max sensitivity settings display ~1 div of noise.

Nothing to see or learn here and suggest you just get on and use it but with an eye kept on the settings you enter.

 

Time to engage that stuff between your ears.....Ch 2 scope setting is at 10mV/div but for a 10x probe.....in other words Ch 2 is set for max sensitivity......1 mV/div.
In most DSO's max sensitivity settings display ~1 div of noise.

Nothing to see or learn here and suggest you just get on and use it but with an eye kept on the settings you enter.

I understand that DSO's inherently have a bit more "noise" than the older CRT vector scopes, but, it is the zero - Ground offsetting positive by the ~ 5 mV level. It will have that noise, but the zero reference "noise" should stay close to and balanced about true zero... ?? Thanks for your reply...
P.S. In any event, what I'm questioning is why is Channel 2's zero level being affected by changing Channel 1's voltage setting??

 

I understand that DSO's inherently have a bit more "noise" than the older CRT vector scopes, but, it is the zero - Ground offsetting positive by the ~ 5 mV level. It will have that noise, but the zero reference "noise" should stay close to and balanced about true zero... ?? Thanks for your reply...

I understand that DSO's inherently have a bit more "noise" than the older CRT vector scopes, but, it is the zero - Ground offsetting positive by the ~ 5 mV level. It will have that noise, but the zero reference "noise" should stay close to and balanced about true zero... ?? Thanks for your reply...

Certainly any channel 0V level should be close to the 0V position and as your OP states this can sometimes be a FW issue however it can also be temp related in that the position can drift slightly as the unit warms up.
I suggest you get it good and warm with say 30 mins running then run the scopes internal Self Cal which should negate any errors of this type.
If it remains then yes it certainly could be called a bug.

 

Certainly any channel 0V level should be close to the 0V position and as your OP states this can sometimes be a FW issue however it can also be temp related in that the position can drift slightly as the unit warms up.
I suggest you get it good and warm with say 30 mins running then run the scopes internal Self Cal which should negate any errors of this type.
If it remains then yes it certainly could be called a bug.

Got ya on the temperature and being a new scope, I kept that puppy on for most of the day, to help weed out infantile failure.... It was on for HOURS with the issue remaining....