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Performance Verification
4–46
1780R-Series Service Manual
h. Connect the output of the function generator to the test oscilloscope
vertical amplifier input. Set the generator controls for 0 V to +10 V
square waves as displayed on the test oscilloscope CRT.
i. Disconnect the function generator output signal from the test oscillo-
scope. Connect the generator output square wave signal to the RGB
Parade Display Test Connector input BNC connector.
j. Check that the first or left-hand waveform ends 6.7 major divisions ±0.7
major division to the left of the location noted in part g. of this step.
k. Disconnect the generator square wave signal and RGB Parade Display
Test Connector from the REMOTE connector. Disconnect the Color Bar
signal from the CH A INPUT connector.
38. Check External Horizontal Input Sensitivity
Supplemental: Sawtooth input of up to 5 V is nominally a 10-division
horizontal sweep.
a. Connect the VAC output to the 1780R-Series EXT HORIZ input
connector.
b. Set the VAC to 999.9 mV.
c. Press the MEASURE button to On and select the ICPM mode on the
menu. (The instrument will automatically select X25 sweep magnifica-
tion.) Set the MAGNIFIER to X5.
d. Use the HORIZ POS control to center the trace (two dots) on the
Waveform CRT.
e. Check that the horizontal sweep length is 9 to 11 major divisions.
f. Set the MEASURE button to Off to exit the ICPM mode of operation.
g. Disconnect the VAC signal from the EXT HORIZ input connector.
39. Check Differential Gain
Requirement: Deflection Factor: 5% dG deflects the trace 50 IRE (NTSC) or
500 mV (PAL) within a tolerance of ±5%. Residual dG: ≤0.2%, last 90% of
trace. Calibrated dG Resolution: 0.1%; Accuracy: 0.1% ±10% of reading;
Range: ±5%.
a. Connect a 40 IRE (280 mV for PAL) Modulated 5-Step Staircase signal
from the television test signal generator to the 1780R-Series CH A
INPUT connector. Terminate this loop-through connector into 75 W.
b. Set the generator 5-Steps button to Off. (Leave the subcarrier modulation
On.)