If you did a factory reset then I doubt it's the settings.
What's your probe set to? 1x or 10x? How are you probing? Do you press the hook on until it clicks into place?
What's your grounding like? Does your mains socket have a ground wire?
I've tried a couple of the Rigol probes that came with the unit and another probe I already had. I've tried them on 1x and 10x. I pulled the hook off one of the Rigol probes and put it back. I connected the probe to the calibration output on the oscilloscope with and without the probe's ground clip connected to the ground tab under the signal output. I also connected a function generator to the oscilloscope through a BNC cable. The double trace was always there.
Grounding should be good. The house I'm in was built about 30 years ago in compliance with the codes of the time. All the wall sockets have dedicated ground conductors. The ground and neutral wires are bonded only in the main breaker panel as they should be per the NEC, and the ground is connected to a copper ground rod driven into the ground near the main panel.
I verified continuity between the oscilloscope's ground and the power cord's ground prong. I tried plugging the oscilloscope into a surge protector that provides filtering and directly into several wall sockets on different circuits, but the double trace persisted.
Connect the probe to the calibrator output. That should be a known good signal.
The screenshot I posted of the square wave is the oscilloscope's calibration output. The sine wave in the other screenshot is from a function generator connected through a BNC cable.
Hi Porcine Porcupine,
Do you have this problem only on channel 1, or on all of them?
Are you using a probe? Did you try the other probes?
The same double trace is displayed on all four channels.
I've tried two of the supplied probes and a third one I already had. I also tried connecting the oscilloscope with a BNC cable to a function generator. The double trace is always there.
It certainly looks like peak detect, is the 2nd sine image triggering on the wrong edge?
I'm not sure about the triggering. The sine wave looked a bit jittery like maybe it wasn't properly triggering consistently, but I attributed that to the cheap function generator (Sinometer VC2002) I was using.