Keithley 2700, Service Manual

Page: 34 / 174

1-18 Performance Verification
Model 7700 verification
Use these procedures to verify measurement accuracy through the Model 7700 20-Channel
Multiplexer Card.
NOTE Although the following tests are based on the Model 7700 20-Channel Multiplexer,
the same general procedures can be used for other plug-in modules that have similar
capabilities. Refer to the Model 2700 User’s Manual for specific information on ter-
minals and connections for other plug-in modules.
Verifying DC voltage
Check DC voltage accuracy by applying accurate voltages from the DC voltage calibrator to
the Model 7700 input terminals and verifying that the displayed readings fall within specified
limits.
CAUTION Do not exceed 300V DC between plug-in module INPUT H and L termi-
nals or between any adjacent channels.
Follow these steps to verify DC voltage accuracy:
1. Connect the Model 7700 CH1 H and L INPUT terminals to the DC voltage calibrator as
shown in
Figure 1-8 .
NOTE Use shielded, low-thermal connections when testing the 100mV and 1V ranges to
avoid errors caused by noise or thermal effects. Connect the shield to the calibra-
tor’s output LO terminal.
Figure 1-8
Connections for Model 7700 DC volts verification
H L H L
AMPS
H L H L H L H L H L H L
LO
CH21 CH22 CH11 CH12 CH13 CH14 CH15 CH16
H L H L H L H L
CH17 CH18 CH19 CH20
SENSE
(OHMS, 4 WIRE)
INPUT
(V, 2 WIRE)
H L H L H L H L
CH7 CH8 CH9 CH10
H L H L H L H L
H L H L H L H L
INPUT SENSE CH1 CH2
CH3 CH4
CH5 CH6
CH1
Output HI
Output
LO
Calibrator (Output DC Voltage)
Note: Use shielded, low-thermal cables
for 100mV and 1V ranges.
Model 7700