Section II. OA-3633(*)/GRC, TROUBLESHOOTING PROCEDURES

TM 11-5820-498-35

Figure 3-3. Connecting power to OA-3633/GRC using PP-2953(*)/U and TF-523/U.

CX-4720/VRC to the male receptacle on the power

distribution box may be connected to another

distribution box (D, fig. 8-4).

piece of equipment using the CX-4721/VRC.

(b) Connect the elliptical receptacle on the

(d) Turn on and adjust the output of the dc

power distribution box to POWER INPUT recep-

power supply to 25.5 volts. Set the PWR switch on

tacle on the rear of the AM-2060(*)/GRC.

the AM2060(*)/GRC to ON when desired.

Section II. OA-3633(*)/GRC, TROUBLESHOOTING PROCEDURES

than the positive battery terminal and it is con-

3-5. Troubleshooting OA-3633(*)/GRC

a. When the AM2060(*)/GRC resistors R6, R7,

nected to the vehicular chassis by a bonding strap.

and R8 (fig. 3-18) are charred, there will be no

( 2 ) Install Suppressor, Electrical MX-

audio output from the AM2060(*)/GRC tO the

7778/GRC in the battery distribution circuit

receiver-transmitter. These charred resistors usu-

of the vehicle. Installation procedures are pro-

ally indicate that the power cable in the vehicle

vided in TM 115195-223-15, which also covers

( u s u a l l y the CX-4720/VRC) in which the

maintenance o f the suppressor. T h e M X -

AM-2060(*)/GRC had been used, had been con-

7 7 7 8 / G R C protects the vehicle from circuit

nected incorrectly to the vehicular battery. That

overload (short circuit) in the radio (and inter-

is, the CX-4720/VRC negative leads (blue-green)

com) equipment and the radio (and intercom)

had been connected to the battery positive termi-

equipment from electrical transient voltages in

nal, and the positive leads (red-white) had been

the vehicle electrical system.

connected to the battery negative terminal. To

b. When trouble is suspected in the application

prevent incorrect battery connections, the follow-

of operating dc voltages to the receiver-transmit-

ing precautionary procedures are recommended:

ter that was used with the AM-2060(*)/GRC,

(1) Mark the battery terminals of the vehicu-

check the AM2060(*)/GRC output circuits by

lar battery power cable so that the person that re-

performing measurements of the output voltages

places the cable leads to the battery knows the

and resistances at connector J2 (para 38, fig.

positive power cable lead(s) and the negative

3-6).

power cable lead(s). The battery negative termi-

c. When trouble is suspected in the audio ampli-

nal can be identified by the fact that it is smaller

3-5