Keithley 2520, Service Manual, Page: 22 / 137

1-10 Performance Verification Model 2520 Pulsed Laser Diode Test System Service Manual
Figure 1-2
Connections for voltage measurement verification tests
CURRENT
OUTPUT
VOLTAGE
SENSE
CAT I
DETECTOR 1 DETECTOR 2
BIAS
CURRENT
INPUT
ISOLATION FROM EARTH: 10V MAX.
HI
HI
LO
LO
!
!
Model 2520 Testhead
BNC Cables
Output HI
Calibrator (Output DC Voltage)
VOLTAGE
SENSE HI VOLTAGE
SENSE LO
Output LO
Shield
Current source accuracy
Follow the steps below to verify that Model 2520 current source accuracy is within
specified limits. This test involves setting the output current to a specific value and
measuring the current with a digital multimeter.
1. With the power off, connect the digital multimeter and characterized 10
Ω
to 15
Ω
resistor to the testhead CURRENT OUTPUT jacks, as shown in Figure 1-3 .
NOTE See Figure 1-4 and Figure 1-5 for mounting and connections of parallel
resistors.
2. Turn on the Model 2520 and DMM, and allow them to warm up for a minimum of
one hour.
3. Restore front panel (BENCH) defaults as outlined previously in “Restoring factory
defaults” on page 1-6 .
4. Select the DC mode as follows:
a. Press CONFIG then LASER I
L
.
b. Select SHAPE, then press ENTER.
c. Select DC, then press ENTER.
d. Press EXIT to return to normal display.
5. Press the LASER I
L
key, then the EDIT key, and select the Model 2520 500mA
source range with the RANGE key.
6. Select the DMM DC voltage function, and enable auto-range.
7. Press the EDIT key to enter the EDIT mode. Using the EDIT and or numeric
keys, set the Model 2520 current source output to 500.00mA, then turn on the
outputs by pressing the ON/OFF OUTPUT key.
8. Note the DMM voltage reading, then turn off the output by pressing the ON/OFF
OUTPUT key.