Wondering if anyone else has noticed a problem with channel 4 being off in the vertical scale, especially noticeable in the 500uV scale?
Not sure if I need to add this to the bugs thread, so though I'd ask here first if any other 2000X Plus users have noticed the same thing. Its only with channel 4, but even having left the scope on for many hours to warm up and run multiple self calibrations (just before these screen shots again) I seem to see a large offset with nothing connected to channel 4's inputs.
I've noticed it because I've been doing some measurements using several of the channels for inputs and outputs of a signal processing circuit I'm working on and wondered why I was always having the trace on channel 4 always as showing as being off, when I'm expecting an essentially zero offset. You'll see from the measurements this is also affecting Pk-Pk and RMS measurements as well. As I was trying to measure noise on an opamp circuit, these Pk-Pk and RMS values were worrying me, but realised I think there's this scope issue with channel 4.
I realise on a 500uV scale, there will always be some slight offsets, and I've switched on the other channels 1-3 to show as a comparison as well. Channels 1-3 do what I'd expect, but I've noticed the problem now several times with channel 4. So I've just done 2 self calibrations in a row to try and fix it, but still there. It doesn't seem to make a difference in 8 bit or 10 bit mode either.
I've been able to narrow it down to being the worst when channel 4 is DC coupled with 50 Ohm termination. This is my first screenshot. Second is not as bad when in 1M Ohm termination, but still too far out for my liking, especially for this scale. These are all taken with nothing connected to any of the inputs, to try and isolate the issue, but the problem is coming up with my supplied probes being connected as well.
Is it a hardware issue with channel 4 on my scope? Or is this something that needs to be fixed with a firmware update to correct the self calibration function for channel 4?
Be interested if others could try it on their scopes with channel 4 in the 500uV scale and see if they notice the same issue.
Thanks.