Power Supply.

Figure 7. Demodulator control - equipment setup.

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

(7) If oscilloscope does not indicate approximately 0

Do not perform power supply checks if all

volt, perform b(2) below.

other parameters are within tolerance.

(8) Adjust demodulator gain for 0-carrier reference

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

(9) Connect oscilloscope probe to junction of R5307

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.

(2) Adjust output of autotransformer (Al) from 105 to

125 volts ac then back to 115 volts. DC voltmeter

indication will remain between -14.85 and -15.15 volts.