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Model 2750 Multimeter/Switch System Service Manual Performance Verification 1-21
770
0 V
eri
fication
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 the 7700 plug-in module INPUT H and
L terminals 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 calibra-
tor as shown in
Figure 1-9 .
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 cal-
ibrator’s output LO terminal.
Figure 1-9
Connections for Model 7700 DC volts verification
2. Install the Model 7700 in Slot 1 of the Model 2750, then turn on the power and
allow the unit to warm up for two hours before proceeding. Be sure the front panel
INPUTS switch is set to the REAR position.
3. Select the DC volts function by pressing the DCV key, and set the Model 2750 to
the 100mV range. Close Channel 1 by pressing the CLOSE key, then ENTER for
“SINGLE” channel, and then keying in 101.
4. Set the calibrator output to 0.00000mV DC, and allow the reading to settle.
5. Enable the Model 2750 REL mode. Leave REL enabled for the remainder of the
DC volts verification test.
6. Source positive and negative and full-scale voltages for each of the ranges listed in
Table 1-10 . For each voltage setting, be sure that the reading is within stated limits.
7. Press the OPEN key to open Channel 1.
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