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Performance Verification
4–42
1780R-Series Service Manual
h. Select CURSOR 1 on the Waveform CRT.
i. Turn the Precision Measurement knob so that CURSOR 1 bright-up spot
overlays CURSOR 2 bright-up spot.
j. Check that the DT readout on the Waveform CRT is between 63.550 ms
and 63.560 ms. (The readout for PAL should be between 63.995 ms and
64.005 ms.)
k. Set the TIME CURSORS button to Off.
l. Disconnect the Color Bar signal from the instrument.
34. Check Sweep Rates and Timing Accuracy
Requirement: See Table 4–4.
Table 4–4: Sweep Timing and Linearity
Line Magnifier
Sweep Rate
Readout
Time Cursors
DT Readout
Check Timing*
Accuracy
Check Linearity*
ONE–LINE OFF (X1) 5.0 ms/DIV 50.0 ms ±1 ms ±0.5 ms
TWO–LINE OFF (X1) 10 ms/DIV 100.0 ms ±2 ms ±1.0 ms
THREE–LINE OFF (X1) 15.0 ms/DIV 135.0 ms** ±2.7 ms ±1.35 ms
ONE–LINE ON (X5) 1.0 ms/DIV 10.000 ms ±0.2 ms ±1 minor div.
ONE–LINE ON (X10) .50 ms/DIV 5.000 ms ±0.1 ms ±1 minor div.
ONE–LINE ON (X20) .25 ms/DIV 2. 500 ms ±0.075 ms ±1 minor div.
ONE–LINE ON (X25) .20 ms/DIV 2.00 0 ms ±0.06 ms ±1 minor div.
ONE–LINE ON (X50) .10 ms/DIV 1.000 ms ±0.03 ms ±1 minor div.
ONE–LINE ON (X100) .05 ms/DIV 0.500 ms ±0.025 ms ±1 minor div.
* Applies to the center 10 divisions of the sweep. Exceptions: Applies to center 9 divisions for THREE–LINE sweep when
using TIME CURSORS for measurement. For magnified sweep measurement, exclude the first 2 divisions.
** When going from THREE–LINE back to ONE–LINE, turn the Precision Measurement knob counterclockwise until the TIME
CURSORS 2 DT readout is 50.0 ms. By doing this, the correct CURSOR 2 bright-up dot will appear in the viewing area.
Continue checking the remaining sweep rates by using the information provided in Table 4–4 and the detailed procedure
as a guide.
a. Check that no signal is applied to the CH A INPUT. Check that Black
Burst is applied to the EXT REF connector and this loop-through is
terminated into 75 W.
b. Check and/or set the 1780R-Series controls as follows: RIGHT
DISPLAY–WFM, INPUT–CH A, REF–EXT, WFM HORIZONTAL–
ONE–LINE and MAGNIFIER–OFF.