b. Adjustments
(3) Set HORIZONTAL DISPLAY control on
waveform monitor (A7) to 2 FIELD and MAGNIFIER to
(1) Adjust R678 (fig. 6) until start of O-carrier
X25.
reference pulse is 12 microseconds from leading edge of
(4) Adjust waveform monitor controls to display 0-
horizontal sync pulse.
carrier reference pulse. If start of 0-carrier reference
(2) Adjust R687 (fig. 6) for 0 volt dc indication on
pulse is not 12 +1 microseconds from leading edge of
oscilloscope.
horizontal sync pulse, perform b(1) below.
(3) Adjust R688 (fig. 6) for 0-volt dc indication on
(5) Adjust gain of station demodulator (fig. 7) for 0-
oscilloscope.
carrier reference pulse amplitude of 120 IRE (857
millivolts).
13. Power Supply.
(6) Connect oscilloscope (A4) to P679-5 (fig. 6),
using probe (B2).
NOTE
Do not perform power supply checks if all
volt, perform b(2) below.
other parameters are within tolerance.
pulse amplitude of 100 IRE (7.14 millivolts). Verify that
a. Performance Check
VIR signal 50 IRE level to O-carrier reference pulse ratio
(1) Connect dc voltmeter (A3) to -15 volt test point
is correct.
(fig. 6) and chassis ground. If dc
voltmeter does not
indicate between -14.85 and -15.15 volts, perform b(1)
and R5606 (fig. 4). If oscilloscope does not indicate
below.
approximately 0 volt, perform b(3) below.
125 volts ac then back to 115 volts. DC voltmeter
indication will remain between -14.85 and -15.15 volts.
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