I've recently acquired a 1054Z and I love it. I've been playing with it, messing with the functionality and trying to replicate bugs. I expect everything to have bugs, but I want to be sure I know what they look like and how to reproduce them so that I am able to recognize them should they occur when I am actually taking a measurement.
The RMS bug seems to be the major remaining issue since the last firmware update (which I have done) and I noticed something odd with it. I'm using the 4 probes that came with it on the pins of a 47ohm resistor and am feeding a 1kHz sine wave from a function gen (yeah, a cheap FY3200S). The Vpp is 4.8V, so the Vrms should be ~1.71V. I can reproduce the bug just fine, I get 1.69V, 1.81V, 1.82V, 1.83V for the RMS on CH 1-4 respectively (My EEVBlog meter reads 1.680V). Nothing new or interesting there, Ch1 is correct and the other 3 are high. I can disconnect the probe for channel N and N+1 drops down to 1.69V. Again, nothing new, exactly as reported by others. However, when I disable channel N with the probe connected the relay clicks and the trace disappears, however the value on CH N+1 doesn't drop! I can even physically disconnect the probe after the channel has been turned off and the "extra" is still appearing in CH N+1. If I turn CH N back on (without reconnecting the probe), CH N+1 then drops to ~1.69V (±0.02 or so).
This I think cements that it is truly a problem in software, and some value somehow bleeding over.
I can take screen shots, but I think this table would be clear enough, and more concise.
NB: All channels on, All probes connected, triggering off CH 1 and all values are the Rms measurements.
CH1 CH2 CH3 CH4
1.69V 1.81V 1.82V 1.82V
Disable Ch2
1.69V ***** 1.82V 1.82V
Disconnect Ch2 probe
1.69V ***** 1.82V 1.82V
Enable Ch2 probe (still disconnected)
1.69V 691mV 1.69V 1.82V
Reconnect Ch2 probe
1.69V 1.81V 1.82V 1.82V
Same as above, but performing the same cycle with Ch3
1.69V 1.81V 1.82V 1.82V
1.69V 1.81V ***** 1.82V
1.69V 1.81V ***** 1.82V
1.69V 1.81V 683mV 1.69V
1.69V 1.81V 1.82V 1.82V
Same as the first two, except I moved the trigger to Ch4
and am performing the cycle with Ch1
1.69V 1.81V 1.82V 1.82V
***** 1.81V 1.82V 1.82V
***** 1.81V 1.82V 1.82V
27.8mV 1.67V 1.82V 1.82V
1.69V 1.81V 1.82V 1.82V