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The calibration kit option (two precision resistors) is required to perform re-calibration. No additional instruments are required since the DP97 self-calibrates as follows:

Caution: Do not proceed unless specified resistors are available. Failure to do so may invalidate the warranty.

a)With the supply disconnected, remove the instrument case cover by removing the two screws on the rear panel and sliding the cover off the rear of the instrument.

b)Insert the jumper JP1 (shorting connector) – this places the DP97 into self-calibrating mode.

Connect the supply and switch on*. Calibration is simply a matter of connecting the precision resistors in sequence. The necessary value of the resistor, together with the input to which it has to be applied is indicated on the display. The steps are as follows:

*At this point, the existing calibration has now been over-written by default values. The procedure should therefore now be completed.

i)Connect 100 Ohm calibration resistor to PRT INPUT a.

ii)Press “SPAN s ” and display will show a value close to 100 Ohms. If the value shown is wrong by more than 1.00 Ohms, a fault exists and the Instrument must be returned for rectification.

iii)Press “SPAN s ” again and the instrument will compute the average value of 16 readings of the resistor value.

iv)When the display reads “A = 250”, connect the 250 Ohm calibration resistor to input A.

v)Press “SPAN s ” and display will show a value close to 250 Ohms. If the value shown is wrong by more than 1.00 Ohms, a fault exists and the instrument must be returned for rectification.

vi)Press “SPAN s ” again and the instrument will compute the average value of 16 readings of the resistor value.

vii)Repeat steps (I) to (vi) for input B.

The DP97 then returns to a normal power-up state, PRT A, degrees C.