Agilent 6612C cannot avoid OUT OF RANGE error for current P2 cal

[EE-digger]

A friend purchased this from BRL, with their cal, about 6 months ago and had not used it until now.

The unit cals fine for voltage and low current.

For CURRENT cal, I can display and set the data for the P1 parameter but get an "OUT OF RANGE" display when displaying the P2 parameter.

I started cheating by cal at the front panel, thinking it must be fairly close, then switched to the rear to be safe.

Has anyone run into this message and found the cause?

[EE-digger]

I discovered that the B1A diagram is wrong.  Load should be 1.1 ohm (not k) per youtube 

By using the current measure of the DMM, I got high current cal to work but now, low current cal shows the OUT OF RANGE when displaying a parameter P1.

Any ideas?  Is the firmware just flakey?

[julian1]

Is it possible to run unit, on the current range that fails cal and with a load? Then measure voltage drop on the current-sense resistor and determine if it makes sense, and if the current range switching works. This would help establish whether the fault is analog or digital/firmware. If analog, then just work forward in signal chain - check current at the ADC etc.

[EE-digger]

Thanks for the suggestions and they would make good next steps.  Unfortunately I can't do a deeper dive at this time.

But, fixed it !  Actually, it was never broken.

I had tried this previously but the OUT OF RANGE for high current threw me.

So, high current must be cal'ed directly into the DMM current range, no B1A diagram nonsense.

Then, the low current is cal'ed with the 1.1k resistor.  The data entry must be in AMPS.  If you enter 17.655 (the DMM mA display) you will get the OUT OF RANGE.  It must be entered as .017655

Once cal'ed, this is a nice little supply.  My friend bought it for the low current measure capability for small radio and other work.  I tried to convince him not to rely on the power supply but now this looks pretty good.