NO CURRENT IN RECEIVE DC LOOP MODEM IN MARK-HOLD CONDITION.

TM 11-5805-387-34-2

MALFUNCTION/SYMPTOM

PROBABLE CAUSE

TEST PROCEDURE

INDICATION

YES

4. With receiver module A4 removed (para

Continuity

Go to 5.

Replace

2-8), check continuity of relay K1 with

defective

MODE SELECTOR switch at positions

relay K1

850 HZ and 85 HZ (fig. FO-8).

(para 3-9).

5. Replace module A4, set MODE SELECTOR

Input signal

Go to 6.

Replace

switch at 85 HZ DIVERSITY. Check for

present on

defective

signal continuity across terminal 1 of filter

ANIUSM-281A

filter FL6

FL6 (fig. FO-8).

(para 3-9).

6. Set MODE SELECTOR switch at 850 HZ.

Input signal

Replace

Check for signal continuity across terminal

present on

defective

3 of filter FL7 (fig. FO-8).

ANIUSM-281A

module A4

filter FL7

(para 2-8).

(para 3-9).

(11) NO CURRENT IN RECEIVE DC LOOP

Defective: Meter function switch S3. Receiver

MODEM IN MARK-HOLD CONDITION.

Module A4. Loop battery module A5.

Do all continuity and resistance checks with all power removed.

1. Check continuity of METER FUNCTION

Continuity

Go to 2.

Replace

switch S3 (fig. FO-8).

defective

switch S3

(para 3-8).

2-18