Component Interface Output Logic Discrete Signals Test (CRC)

TM 55-4920-430-13

(10) Disconnect the positive lead of the multimeter from receptacle pin J1-FF. Connect at recep-

tacle pin J1-BB.

(11) Set the YAW switch to OPERATE. Monitor the Feedback No. 2 output on the digital mul-

timeter. Within 1.6 to 2.4 seconds, the multimeter shall indicate 1.5 volt ac in-phase. The indication

shall rise to 2.18 to 2.58 volt ac, in-phase.

(12) Set the YAW switch to RESET. The multimeter shall indicate less than 0.03 volt ac.

(13) Disconnect the positive lead of the digital multimeter from receptacle pin J1-BB. Connect it

to receptacle pin J1-LL.

(14) Set the YAW switch to OPERATE. Monitor the Feedback No. 3 output on the digital mul-

timeter. Within 1.6 to 2.4 seconds, the multimeter shall indicate 1.5 volt ac. The indication shall rise to

2,18 to 2.58 volts ac, in-phase.

(15) Set the YAW switch to RESET. The multimeter shall indicate less than 0.03 volt ac.

(16) Reduce the output of both power supplies to O.

(17) Disconnect the multimeter.

(18) Disconnect No. 2 power supply.

(19) Disconnect No. 1 power supply and decade box.

4-57. Component Interface Output Logic Discrete Signals Test (CRC). The output logic discrete

signals, simulate the aircraft components that interface with the AFCS computer. The two-position tog-

gle switches on the test set simulate the logic discrete input signals to the AFCS computer. The toggle

switches apply a voltage, an open circuit, or a ground as required for the following discrete outputs.

Check the following logic discrete signals by operating the switches and measuring output signals at

the receptacle pins listed below. Use a digital multimeter, set appropriate range and function.

NOTE

q When a test includes a requirement that an ac voltage be in-phase

or out-of-phase, oscilloscope channel A must be connected across

the digital multimeter. Oscilloscope channel B must be connected

to the ac source and the oscilloscope externally triggered from the

ac source.

q The minus sign (-) before an ac voltage indicates out-of-phase.