Keithley 2306 calibration routine problem

[rastro]

Has anyone gone through the calibration procedure on a Keithley 2306?
I seem to be having problems after the first few steps.

After step 3 (page 240 pdf) of the calibration procedure I should expect the 2306 to output around 14.0000VDC.  Instead the DMM reads 14.4484 and the 2306 display similar 14.4488.  Both reading are pretty close to each other but no where near the expected 14.0000VDC.  Also, in normal operation, setting the volts to 14.000VDC reads correctly on both DMM and 2306 readback - there is no gross misalignment starting out.

On step 4 I can adjust the 2306 to match the reading on the DMM (close to 14.45VDC).  When I press enter it goes to step 5 and now the DMM and 2306 readback is very close to 14.0000VDC.  Again I can adjust the read back values to match. 

Is this normal? 

Background:
The unit is generally working OK but performance test is slightly out on current readback.  Therefore I wanted to go through the system calibration.  I'm using a Keithley 2000 rather than 2001 so it has one less digit of resolution but presents no material effect on the problem I'm seeing with the calibration routine.  Revision = B16/B01.

Manual:
http://exodus.poly.edu/~kurt/manuals/manuals/Keithley/KEI%202302,%202306%20Service.pdf

[TiN]

Are you using proper sense 4-wire connection in all cases?
I did 2304 calibration, and did not see such big differences. I used automated procedure published here.

[rastro]

Hello TiN,
Thanks for the reply

I have made the connections as described in figure 14-1.  The sense & output are tied together at the connector.  The DMM is connected to the output/sense connections and another line to the respective "DVM IN" of the 2306.  I am sure the wiring is correct.

I looked at the page you posted.  I did run across this before posting - lots of good information.  However the 2304A which has some meaningful differences compared to the 2302 or 2306 units.

I am not running this through GPIB but through the front panel.  Could someone run the first 5 steps of the calibration procedure using the front panel? 

-rastro

[rastro]

So I went ahead and did a full calibration even with the strange behavior on step 4 (page 241).
Some closure:

The manual says it should show "READ1 14.0000 V" but as I said it was showing around 14.45XXVDC on both the DMM and 2306 read back. 
What I did was ignore the procedure value and use the arrows on the front panel to set the 2306 read back to match the DMM reading (only off by a couple of low digits).
The next step "READ2 14.0000 V"  both DMM and 2306 read-back where very close to the stated value  (13.9998 on the DMM) so I matched the 2306 read-back to the DMM value.

I saw similar behavior on channel 2 calibration and did the same as channel 1.

After I finished I went back through the performance verification (page 222) and everything looked good. 

I don't know why there is a difference between the calibration procedure and the actual behavior of the system but apparently it did not impact the final result.

-rastro

[TiN]

Could be just a typo. 2304 manual has typo as well, asking for 4k resistor, while actually need have 4 ohm in place.

If it works good, I'd take it from there

[rastro]

That's good to know.
-rastro