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.
Receive audio module Al
Regulated voltage adjustment;
BFO frequency limits adjustment
Scope module A2
Loop battery module A5
Loop current adjustment
Preregulator board A9
Regulated voltage adjustment
· 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
AUTO MARK HOLD
DC LOOP NO. 1
DC LOOP NO. 2
· Set A3S1 NORM/REV switch to NORM.
· Set A5S1 INT-EXT switch to LOOP 1 and 2-INT.