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Performance Verification
4–36
1780R-Series Service Manual
e. Set the 1780R-Series controls as follows: INPUT to AB1 and WAVE-
FORM GAIN to X5.
f. Check that the amplitude is 3.5 IRE or less for NTSC (25 mV for NTSC
or PAL) as displayed on the Waveform CRT.
g. Set the sine wave oscillator frequency to 15 kHz. Select INPUT–CH A
and set the WAVEFORM GAIN–X5 to Off. Repeat parts d. and e.
h. Check that the amplitude is 3.5 IRE or less for NTSC (25 mV for NTSC
or PAL) as displayed on the Waveform CRT.
i. Disconnect the sine wave oscillator from the instrument. In its place,
connect a leveled sine wave generator signal through a 50 W-to-75 W
minimum loss attenuator and a 75 W feed-through terminator to the
dual-input coupler.
j. Select INPUT–CH A and set the WAVEFORM GAIN–X5 to Off.
k. Set the generator output frequency to 1 MHz.
l. Set the leveled sine wave generator output amplitude control so that the
display on the Waveform CRT is 140 IRE for NTSC (1 V for NTSC or
PAL).
m. Set the the INPUT selection to AB1. Set the WAVEFORM GAIN to X5.
n. Check that the amplitude is 7 IRE or less for NTSC (50 mV for NTSC
or PAL) as displayed on the Waveform CRT.
o. Set the generator output frequency to 3.58 MHz for NTSC (4.43 MHz
for PAL). Repeat parts l. and m.
p. Check that the amplitude is 14 IRE or less for NTSC (100 mV for NTSC
or PAL) as displayed on the Waveform CRT.
q. Move the dual-input coupler from CH A INPUT to CH B2 INPUT.
r. Check common mode rejection. Use parts a. through p. in reverse order
as a guide for checking common mode rejection. The amplitudes for
3.58 or 4.43 MHz, 1 MHz, 15 kHz, and 60 Hz are 14 IRE or less for
NTSC; 100 mV or less for PAL. (Set the appropriate INPUT button to
CH B1 when setting the display reference amplitude and then select
INPUT B1B2 to check common mode rejection).
s. Move the dual-input coupler from CH B2 INPUT to CH B3 INPUT.
t. Check common mode rejection. Use parts a. through p. in the normal
order as a guide for checking common mode rejection. The amplitudes
for 60 Hz, 15 kHz, 1 MHz, and 3.58 or 4.43 MHz are as follows: 14 IRE
or less for NTSC; 100 mV or less for PAL. (Set the appropriate INPUT