TM 55-4920-429-13
(2) Connect the variable thc power supply to receptacle pins J3-x (+) and J3-C. Connect the digital
multimeter, set to measure dc volts, across the HI (+) and LO binding posts. (See FO-8 for connector pin
patterns.)
(3) Adjust the dc power supply to each of the test voltages listed below. Pay particular attention to’
the lead digit and the location of the decimal point. X indicates that the value of a digit is not signifi-
cant.
TEST VOLTAGE (DC)
D MM
0
.XXXX
+19
+1X.XX
+25
+2X.X
+19
+1X.X
+17
+1X.XX
(4) Disconnect the dc power supply from receptacle 3. Disconnect the digital multimeter from
the binding posts.
4-31.
Discrete Signal Monitor Circuit Test. The following test ensures the correct operation of the
SEL 1/SEL 2, SIGNAL SEL 1, and SIGNAL SEL 2 switches, STATUS A and B lights, and associated
circuits.
a. Set the METER SOURCE switch to DISCRETE MON. Set the SEL 1/SEL 2 switch to SEL 1. Set
the SIGNAL SEL 1 switch to RADAR ALT ENGAGED.
b. Test the circuits of the SIGNAL SEL 1 switch as follows: Connect input signals from the dc power
supply to receptacle pins as listed below. Connect the digital multimeter across the output of the dc
power supply. STATUS lights and dmm indications shall be as listed. The VDC indicator shall be on.
The VAC and K-OHM indicators shall be out. (See FO-8 for connector pin patterns.)
C. Disconnect the dc power Supply. Set the SEL 1/SEL 2 switch to SEL 2.
INPUT
SIGNAL SELECT 1
SIGNAL
RECEPTACLE
STATUS
STATUS
SWITCH POSITION
CONDITION
PINS
ALT
BLT
D MM
RADAR ALT ENGAGED
11 Vdc
J3-j (+)
ON
OFF
+10.85 To 11.15
J3-AA
9 Vdc
Same
OFF
OFF
+ 8.87 To 9.13
3 Vdc
Same
OFF
OFF
+ 2.93 To 3.07
Open Ckt
—
OFF
ON
N/A
BARO ALT ENGAGED
11 Vdc
J3-i(+)
ON
OFF
+10.85 To 11.15
J3-AA
Change 2 4-13
