Testing the units I found or confirmed several firmware bugs.
I might be wrong so maybe some of you will do same tests and confirm or not - "it's not a bug is a a feature" style.
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a) "Channel 2 is Off" on screen without any reason when using HOR menu or the Trigger menu.
How to test: just press HOR or Trigger menu. The message will pop up.
(@TheBay noted this bug and I can confirm it).
I think this is a feature with an undesired side effect. I've found that the cause of the "Channel 2 is Off" message stems from the use of the AUTO button. There's also a slightly less annoying work-around than re-entering the CH1/2 menu and switching back to Chan-1.
It turns out that the AUTO button has different behavior depending on what's plugged into the scope's inputs and the channel that's selected in the trigger menu.
(Example-1)
1) Set CHAN-1 to ON and CHAN-2 to OFF and set trigger to CHAN-1. Apply a signal to CHAN-1 only.
2) Press the AUTO button
-one time-.
3) The scope will properly display the signal on CHAN-1 but the AUTO button has also toggled the 'selected' channel to CHAN-2 but didn't turn it on. (Verify this by pressing the CH1/2 button and note the highlighted channel).
4) If the AUTO button is pressed again, it will toggle back to CHAN-1. That would be the work-around in most cases, just press the AUTO button a second time.
(Example-2)
1) Set CHAN-1 to ON and CHAN-2 to OFF, and set TRIGGER to CHAN-1.
apply a signal to CHAN-2only.
2) Press the AUTO button
-one time-.
3) CHAN-1 will turn OFF and CHAN-2 will turn ON and the TRIGGER will be switched to CHAN-2
4) Addition presses of the AUTO button will again toggle the 'selected' channel back and forth. CHAN-1 will remain OFF
(Example-3)
1) Apply signals to BOTH channels, it doesn't matter whether either channel is ON or OFF.
2) Press the AUTO button
-one time-.
3) BOTH channels will turn ON and the scope will trigger on whatever channel the TRIGGER is set to, the AUTO button will no longer toggle between channels.
You may have noticed that certain functions get highlighted on the display after their button is pushed. CH1/2 button will highlight the V/Div in the lower left corner of the display, the HOR and TRIG buttons will highlight their respective functions. With a previous unit I had (and returned) running firmware V4.1.0, the AUTO button would only toggle channel selection when the V/Div indicators were highlighted, if either the HOR or TRIG info on the screen was highlighted the AUTO would not toggle. Seems that in V5.4.0, AUTO will toggle regardless of which function is highlighted.
There may be other behavioral issues with the AUTO button that I haven't run across yet.