Tektronix Option 10 Service Manual page 91

HDTV Option-Performance Check and Adjustment Procedures
f. Set TRIGGER COUPLING to LINES.
g. Use the Horizontal POSITION control to align the
positive edge of the first pulse with the A REF OR DLY POS
cursor.
h. Set CH 2 VOLTSIDIV to 100 mV. Use the A control to
produce a At reading of 13 ps.
i.
Reduce the generator period to the point at which the
display is stably triggered, but any further reduction would result
in an unstable display.
j.
CHECK-That the positive edge of the second pulse is
located in the area between the two cursors.
k. Set:
CH 2 INVERT On
TRIGGER SLOPE
+
I. Adjust the pulse width so that the negative edge of the
second pulse is aligned with the second cursor.
m. Reduce the generator period to the point at which the
display is stably triggered, but any further reduction would result
in an unstable display.
n. CHECK-That the negative edge of the second pulse is
located in the area between the two cursors.
Remove the XI 0 attenuator from the input signal path.
Set:
CH 2 INVERT OFF
TRIGGER SLOPE
-
(minus)
CH 2 VOLTSIDIV 1 V
Repeat parts i through n.
Disconnect the test equipment from the instrument.
6. Check Trigger Modes
a. Set:
CH 2 INVERT Off
CH 2 VOLTSIDIV 500 mV
AV and A t Off
A SEClDlV 100 p s
TRIGGER SLOPE
-
(minus)
TRIGGER COUPLING FLD 1
24x5~124678 Options Service
b. Connect the composite sync output from the TV
mainframe linearity generator via a
75-Cl
cable and a 75-52
termination to the CH 2 input connector.
c. Rotate the A control until the readout indicates that the
first line of the video signal is displayed ("F1 : I ").
d. CHECK-That the oscilloscope is triggered on the first
line of Field 1.
e. CHECK-That a slight counterclockwise rotation of the
A control changes the readout to indicate the highest line
number in the previous field for a multifield input signal. For
example, using an NTSC signal, the readout would be "F2:262";
and using a 1050 HDTV signal, the readout would be "F2:I 050".
f. CHECK-That the oscilloscope is triggered on the last
line of Field 2.
g. CHECK -That rotating the A control counterclockwise
backward through the second field of the signal eventually
changes the readout to indicate the highest line number in the
previous field for a multifield input signal. For example, using an
NTSC signal, the readout would change to "F1:263"; and using a
1050 HDTV signal, the readout would be "F2:525".
h. CHECK-That the osciIloscope is triggered on the last
line of Field 1.
i. Set TRIGGER COUPLING to ALT.
j.
Rotate the A control until the readout indicates that the
first lines of the two frames are displayed (66ALT1").
k. CHECK-That the oscilloscope is triggered on the
correct lines of the two fields.
I.
CHECK-That a slight counterclockwise rotation of the
A control changes the readout to indicate the highest line
number common to both fields for a multifield input signal. For
example, using an NTSC signal, the readout would be
"ALT262"; and using a 1050 HDTV signal, the readout would be
"F2:525".
m. CHECK-That the oscilloscope is triggered on the
correct lines of the two fields.
n. Disconnect the test equipment from the instrument.