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Performance Verification
4–64
1780R-Series Service Manual
Check that the generator is internally connected so that the SCH can be
varied. (Refer to P339 on the generator A21 Sync Lock board.)
l. Check that by turning the generator Subcarrier Phase control clockwise,
the SCH dot “flips” between 80_ and 115_ (typical range). SCH phase
can be varied ±70_ from 0_ without changing fields. If this performance
requirement and the one described in part e. of this step are met, the
360_ requirement will also be met.
m. Leave the Color Bar signal connected to the CH A INPUT. Disconnect
the coaxial cable from the other CH A INPUT connector; terminate this
loop-through connector into 75 W. Connect Black Burst from the
generator to the EXT REF connector; check that this loop-through
connector is terminated into 75 W.
n. Press the generator Horiz Unlock button.
o. Check that the SCH dot locks into a stable position within ≥1 second
when the generator Horiz Unlock button is released.
p. Remove the 75 W termination from the EXT REF connector.
q. Check that the SCH dot locks.
r. Connect two 75 W terminations to the EXT REF connector.
s. Check that the SCH dot locks.
t. Remove one of the terminators from the EXT REF connector.
u. Leave the Color Bar signal connected to the instrument.
57. Check WFM Trace Rotation and Orthogonality
Requirement: Trace Rotation Range: ≥±1_ from horizontal. Orthogonal-
ity: ±1_.
a. Check that a 75% Amplitude Color Bar signal is applied from the
television test signal generator to the CH A INPUT connector.
b. Adjust the VER POS control so that the waveform blanking level is
positioned to the graticule baseline (0 IRE for NTSC; 0.3 V for PAL) as
displayed on the Waveform CRT.
c. Press the CALIBRATE button and select TRACE ROTATION on the
Vectorscope CRT menu.
d. Check that the electronic graticule horizontal lines, displayed on the
Waveform CRT, are parallel to the nearest graticule lines within ±1_.
Check that the electronic graticule vertical lines are perpendicular to the
electronic graticule horizontal lines within ±1_.