Tektronix CSA7404B, Service Manual

Page: 198 / 348

Performance Tests
4- 122
CSA7404B, TDS7704B, TDS7404B, TDS7254B & TDS7154B Service Manual
H
Adjust the sine-wave generator output for 8 divisions of amplitude.
H
From the button bar, touch Trig and select the A Event tab.
H
Touch the Select button.
H
Touch the Comm button. Set Source to Ch1, Type to R Clk, and
Coding
to NRZ.
2. Verify the clock recovery at frequency:
a. From the button bar, touch Trig and select the A Event tab.
b. Set the sine-wave generator to output one of the input frequencies in
Table 4--12 (on page 4--123) that is not yet checked. (Start with the first
setting listed.)
c. Set the instrument Bit Rate to the Recovered clock Baud rate listed in
the table for the current input frequency.
NOTE
. The instrument will attempt to acquire lock once. If the input data is
disrupted, removed, or heavily distorted, the instrument may not acquire lock or
may loose lock. If the recovered clock is not locked to the incoming data, the
waveform display will not be stable (see Figure 4--40). Once the input data is
available, press the PUSH SET TO 50% knob to force the instrument to acquire
lock again.
d. Press PUSH TO SET 50% .
NOTE
. As the input frequency is lowered, adjust the Horizontal SCALE to
maintain about 3 to 5 eyes across the display.
e. Verify that lock is acquired as in Figure 4--40.
f. Repeat substeps b through d for each input frequency and Baud rate
listed in Table 4--12 (on page 4--123).
g. If all tests pass, enter passed in the test record.
3. Disconnect the hookup: Disconnect the cables and adapters from the inputs
and outputs.