Section IV. ADJUSTMENT PROCEDURES

TM 11-5805-387-34-2

Section IV. ADJUSTMENT PROCEDURES

2-13. GENERAL INSTRUCTIONS

Make adjustments after performing maintenance. These tests determine if the modem has been

properly repaired and can be returned to use. Adjustments are necessary after replacing modules A1,

A2, A5, and board A9. The chart below lists the specific adjustments for each.

ASSEMBLY REPLACED

ADJUSTMENT PROCEDURE

PARAGRAPH

Receive audio module Al

Regulated voltage adjustment;

2-14

BFO frequency limits adjustment

2-16

Scope module A2

Centering;

2-17

Alignment

2-18

Loop battery module A5

Loop current adjustment

2-15

Preregulator board A9

Regulated voltage adjustment

2-14

Tools and test equipment: See paragraph 2-2.

Bench test setup: See paragraph 2-4 for test equipment setup.

Modem settings: Before starting each adjustment procedure, preset the modem's front panel controls and

switches this way:

CONTROL OR SWITCH

SETTING

AUTO MARK HOLD

OFF

RECEIVE

NORM

DC LOOP NO. 1

DC LOOP NO. 2

SQUELCH SENS

MIDRANGE

SCOPE INTENSITY

MIDRANGE

METER FUNCTION

REGULATED DC

MODE SELECTOR

850 HZ

RCV/SEND

SEND

BFO

MIDRANGE

ONE WAY/DUPLEX

DUPLEX

AUDIO GAIN

MIDRANGE

ON/OFF

OFF

Internal switches:

Set A3S1 NORM/REV switch to NORM.

Set A5S1 INT-EXT switch to LOOP 1 and 2-INT.

2-33