Hello there!
I was about to start a new thread about but, searching, I found this.
I recently acquired a 6812B that exhibits the same behavior detailed by OP when CC mode engages.
Testing for calibration, set and readback values are within specs (as detailed in the service manual)
The transition between CV and CC mode takes a lot of time.
Aside of this I experience the following:
I connected a 230V 150W incandescent light bulb to output. Current measured is 0.676A
If I set CURR:LEV 0.6 the units stays in CV mode for several seconds. It turns to CC and, as per mode, voltage starts decreasing but very, very slowly. Voltage and current continue to decrease below current set point and after about one hour it stabilises at 0.584 (16mA below set point)
If I connect a 230V 25W incandescent light bulb to output, current measured is 0.105A.
If I set CURR:LEV 0.07 the voltage starts decreasing after turning into CC mode. Voltage and current continue to decrease below current set point and both goes to zero. At this point Unr annunciator goes on and after few second the output is disengaged with PROT annunciator on.
The manual is quite vague about that, also in the user manual a testing procedure is detailed and it looks to disagree with the instrument behavior (at least mine and the OP one)
makes me think that if i set 0.6A the voltage should decrease in order to keep the current drawn by the load stuck at 0.6A but it does not happen.
At page 34, it writes
And it makes me think it should be (almost) immediate and held to the setpoint.
Two units exhibiting the same behavior makes me think it's not a fault but the intended operation.
Could anybody explain me why this is the behavior? Also I do not understand, as per manual page 18, how a load could exhibit negative resistance i.e. a light bulb.
@TheSteve could you be so kind to reproduce my experience on your instrument (and maybe post a video?)