Model 2302-V001
RESISTOMAT
®
Page 25
Brief guide
Operation
Calibration
Test and offset
instructions
RS232 data
output
Introduction &
applications
Description of functions
Accessories and Circuit diagram
Test and offset
instructions
14.
Switch over to 2
Ω
/100 mA. Using P 2, set the same display value as
previously (individual correction of the 100 mA current). If this value
cannot be attained, replace the resistance R 14/120 K .
15.
The ranges 200 m
Ω
/100 mA, 200 m
Ω
/1 mA, 20
Ω
/10 mA, 20
Ω
/1 mA
must now be accurate within
±
0.05 % .
16.
Set a range of 2 k
Ω
, connect an appropriate calibration resistance and
obtain the correct display using P 3.
(Individual correction 100
µ
A).
17.
Do the same in the 20 k
Ω
range using P 4 (10
µ
A).
18.
Set a range of 200 m
Ω
/1 A, connect an appropriate calibration resistance
and obtain the correct display using trimmer P 6.
If required, change R 22. ( P 6 and R 22 on the switch board).
19.
The 20 m
Ω
/ 1 A and 2 m
Ω
/3 A ranges must now be accurate within 0.05 %.
20.
If 2 m
Ω
/3 A exhibits deviations > 0.05 %, R 27 can be corrected (on the
switch board).
21.
20 m
Ω
/3 A must now also be accurate within 0.05 %.
22.
Testing the temperature compensation:
Select any range and connect a calibration resistance.
Turn the "Compensation" on.
Connect the Cu sensor model 2391 to the round socket. As the sensor heats
up, the display (calibration resistance) should drop. At a sensor temperature
of 20
°
C, the correct value of the calibration resistance should appear.
If sensor operation is interrupted (e.g. through unplugging) a 0 is displayed
(no measurement current flows).
23.
In the case of inexplicable errors or compensation errors on the oscilloscope,
test the current for oscillations with the resistance connected.
In the case of devices with serial numbers lower than 9577 680, a pF
capacitor might need to be soldered between the collector and the base of T1
(current generation board).
A zero offset as described in item 12 is required subsequently.
24.
Overload protection of the voltage section:
Voltage at C 6 on the amplifier board max. 700 mV in the case of certain 10-volt
input voltages at the U terminals.