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Performance Verification
4–32
1780R-Series Service Manual
k. Check that the signal blanking level moves less than 3 IRE for NTSC
(21 mV for PAL).
l. Move the coaxial cable with its terminator from the CH A INPUT
connector to the CH B1 INPUT connector. Select INPUT–CH B1 on the
right front panel.
m. Check Repeat parts c. through k. of this step to check CH B1.
n. Move the coaxial cable with its terminator from the CH B1 INPUT
connector to the CH B2 INPUT connector. Select INPUT–CH B2 on the
right front panel.
o. Check Repeat parts c. through k. of this step to check CH B2.
p. Move the coaxial cable with its terminator from the CH B2 INPUT
connector to the CH B3 INPUT connector. Select INPUT–CH B3 on the
right front panel.
q. Check Repeat parts c. through k. of this step to check CH B3.
r. Remove the coaxial cable with its terminator from the CH B3 INPUT
connector. Connect the AC Bounce signal, through a 75 W 10X
attenuator and a 75 W feed-through terminator, to the left front panel
PROBE input connector.
s. Select INPUT–PROBE on the 1780R-Series right front panel. Check
that the CONFIGURE button is On, COUPLING–AC, and PROBE–X10
are selected. Select DC RESTORER–OFF on the menu.
t. Check Repeat parts g. through k. of this step to check the PROBE input.
u. Select COUPLING–DC and DC RESTORER–OFF on the menu. Press
the CONFIGURE button to exit the menu. Select INPUT–CH A on the
right front panel.
v. Set the television test signal generator Linearity Level control to 50%.
w. Disconnect the Linearity signal from the 1780R-Series PROBE input.
22. Check DC Restorer Hum Attenuation
Requirement: Slow Clamp Mains Hum Attenuation: Equal to or less than
0.9 dB. Fast Clamp Mains Hum Attenuation: Equal to or greater than 26 dB.
a. Connect a 60-Hz (50 Hz for PAL) hum signal from a sine wave oscillator
to the 1780R-Series CH A INPUT connector. Do not terminate.
b. Check that a Black Burst signal is applied to the 1780R-Series EXT REF
connector and REF–EXT is selected on the front panel. Check that the
internal jumpers for A2J865, A2J866, and A2J867 are all set to their
factory-set positions.