Performance Tests
CSA7404B, TDS7704B, TDS7404B, TDS7254B & TDS7154B Service Manual
4-91
Instrument under test
50 Ω Coaxial cable
Digital
multimeter
Input
Figure 4- 20: Initial test hookup
1. Install the test hookup and preset the instrument controls:
a. Initialize the instrument: Press the DEFAULT SETUP button.
b. Hook up the test-signal source: Connect, through a 50 Ω precision
coaxial cable, the input of the multimeter to CH 1 through adapters (see
Figure 4--20).
c. Set the Vertical SCALE to 10 mV per division
2. Check input impedance against limits:
a. Measure the impedance:Read and record the measured impedance.
b. Remove the dual banana connector from the digital multimeter (DMM),
turn it 180 degrees and reinsert it in the DMM input.
c. Measure the impedance:Read and record the measured impedance.
d. Add the two measurements and divide the result by 2.
e. Check — Average of the two measurements is ≥48.75 Ω and
≤51.25 Ω. Enter average on the test record.
3. Set the Vertical SCAL E to 100 mV per division and repeat step 2.
4. Repeat steps 2 through 3 for the remaining input channels:
a. Move the test setup to an unchecked input channel.
b. Set the Vertical SCALE of the channel to 10 mV per division.
c. Repeat steps 2 through 3.
5. Disconnect the hookup: Disconnect the equipment from the instrument.
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