DIFFERENTIAL PROBE SI-800(701920)
Calibration Procedure
This procedure is for use by qualified service personnel to adjust 701920 properly. The equipments required are listed in Table 1.

 

No
Item
Minimum Requirements
1
 Power Supply Yokogawa 700938
2
 DMM DC Accuracy > 0.5%
3
 Function Generator Maximum Frequency >1MHz
Sine-wave Distortion < 1%
4
 Oscilloscope Bandwidth >= 20MHz
Accuracy >= 2%

Table 1

This procedure is divided into following steps:
A. Prepare the probe for adjustment.
B. Adjust input bias voltage.
C. Adjust output offset voltage.
D. Adjust CMRR at 60Hz.
E. Adjust square-wave compensation for +input.
F. Adjust square-wave compensation for -input.
G. Adjust CMRR at 1MHz.
A. Prepare the probe for adjustment.
 ¡@A-1. Use a small flat screwdriver to peel the both panels off, referring to figure 1.

Fig. 1

 
¡@A-2. Loosen the four screws on the plastic cases.
¡@A-3. Remove the plastic cases. Figure 2 shows the location of adjustments on top side and bottom side of the metal case.
¡@A-4. Attach the Lemo connector of 701920 to Yokogawa power supply and turn on all test equipments.
¡@A-5. Allow the probe and test equipments to warm up 20 minutes at an ambient temperature of 18 degree Celsius to 28 degree Celsius.
¡@A-6. In order to make following operation easier, use one plastic case to support the metal case and the input head.
 
 

Fig. 2

 
B. Adjust Input Bias Voltage
¡@B-1. Connect the probe as shown in figure 3.
¡@B-2. The value of input bias voltage now is displayed on the digital multimeter.
¡@B-3. Adjust VR3 to make the input bias voltage as small as possible.
¡@B-4. The criterion is -3mV<=Vib<=3mV.
 

Fig. 3

 
C. Adjust output offset Voltage
¡@C-1. Connect the probe as shown in figure 4.
¡@C-2. Adjust VR2 for minimal output offset voltage.
¡@C-3. The criterion is -3mV<=Vout<=3mV.
 

Fig. 4

 
D. Adjust CMRR at 60Hz
¡@D-1. Connect the probe as shown in figure 5.
¡@D-2. Set the output of the function generator to 20Vp-p 60Hz sine-wave, and set the input impedance of the oscilloscope to 50ohm. (Add a feedthrough 50ohm terminator to the input, if the oscilloscope doesn't provide the 50ohm input impedance.)
¡@D-3. Adjust VR1 for minimum Vout displayed on the oscilloscope.
¡@D-4. The criterion is Vout<=1mVp-p.
 

Fig. 5

 
E. Adjust square-wave compensation for +input.
¡@E-1. Connect the probe as shown in figure 6.
¡@E-2. Set the output of the function generator to 10Vp-p, 100KHz square-wave.
¡@E-3. Set the input impedance of the oscilloscope to 50ohm (Add a feedthrough 50ohm terminator to the input, if the oscilloscope doesn't provide the 50ohm input impedance.)
¡@E-4. Adjust VC1 to make the front corner roll off or overshoot of the square-wave displayed on the oscilloscope less than 20mV.
 

Fig. 6

F. Adjust square-wave compensation for -input.
¡@ F-1. Connect the probe as shown in figure 7.
¡@ F-2. Set the output of the function generator to 10Vp-p, 100KHz square-wave.
¡@ F-3. Set the input impedance of the oscilloscope to 50ohm (Add a feedthrough 50ohm terminator to the input, if the oscilloscope doesn't provide the 50ohm input impedance.)
¡@ F-4. Adjust VC2 to make the front corner roll off or overshoot of the square-wave displayed on the oscilloscope less than 20mV.
 

Fig. 7

G. Adjust CMRR at 1MHz
¡@ G-1. Connect the probe as shown in figure 8.
¡@ G-2. Set the output of the function generator to be 20Vp-p, 1MHz, sine-wave, and set the input impedance of the oscilloscope to be 50ohm (Add a feedthrough 50ohm terminator to the input , if the oscilloscope doesn't provide the 50ohm input impedance.)
¡@ G-3. Adjust VC1 slightly for minimum Vout displayed on the oscilloscope.
¡@ G-4. The criterion is Vout<=2mVp-p.
 

Fig. 8

 

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