Lake Shore Model 234/234D User’s Manual
5-8
Service
1.
Output Calibration.
a.
Use a shorting wire to connect SENSOR I+ to SENSOR I–. This is a
short circuit for the sensor.
b. Make sure that the
T/R
switch closed (
R
position), and the
I/V
switch
in the
V
position (closed).
c.
Connect the DVM negative lead to OUT–, and positive lead to OUT+.
Make sure that the 500
Ω
load resistor is also connected to OUT+
and OUT– terminals.
d. Adjust trimpot R38, OUTPUT OFFSET, until the DVM reads zero
±0.05 mV.
e.
Remove the shorting wire from Step a., above.
f. Adjust trimpot R40, OUTPUT GAIN, until the DVM reads 10.0000V
±0.05 mV. Output calibration is complete.
2.
Input Calibration.
a. Make sure that the
T/R
switch
R
position (closed), and the
I/V
switch
V
position (closed).
b. Connect the DVM negative lead to OUT–, and positive lead to OUT+.
Make sure that the 500
Ω
load resistor is also connected to OUT+
and OUT– terminals.
c. Connect the 1 k
Ω
calibration resistor to the screw terminal SENSOR
I+ and SENSOR I– to simulate a sensor load to the Model 234. Use a
shorting wire to connect SENSOR I+ to SENSOR V+, and another
shorting wire to connect SENSOR I– to SENSOR V–.
d. Switch all of the
RANGE
to
OPEN
except
RANGE 4
which is open to
calibrate the input with the 1 k
Ω
calibration resistor.
e. Press the
S2
pushbutton. Wait 5 seconds. The output should read
10 × log(1000) / 6 = 5.0000 volts. If it does not read 5.0000 ±1 mV
then press the
S2
button again.
Summary of Contents for 234
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