TROUBLESHOOTING SYMPTOM INDEX

TM 11-5805-387-34-2

TEST CONDITIONS

Turn on the test equipment and allow a 5-minute warmup period.

When checking all transmit modes except VOICE, set the MODE SELECTOR switch to the desired mode of

operation, and set the TS-799AIUGM-1 controls as follows:

POWER - 115 V ON

RATE - 7.5 BAUDS

DISTORT SELECT - OFF

CURRENT SELECT - 60

MESSAGE TRANSMIT - ON

MESSAGE SELECT - DOT/CY (sets up equipment to produce an output of

alternate marks and spaces)

MESSAGE SELECT - SELECTED PULSES (sets up equipment to produce a

continuous selected character as determined by the position of the MARK -

SPACE toggle switches)

NOTE

With the AUTO MARK HOLD switch in the OFF position use the same procedures to check the

receiving modes; the transmit operation controls both transmitter output and receiver input

through test cable No. 3. Warm up the BFO oven for 5 minutes before performing tests or

adjustments in the 850-Hz mode. After the warmup period, adjust the BFO control for a

symmetrical Lissajous pattern (when keying).

2-5. TROUBLESHOOTING SYMPTOM INDEX

Use this Index to quickly find procedures in the troubleshooting chart.

TROUBLESHOOTING SYMPTOM

PROCEDURE NO.

PAGE

MODEM

Does not transmit tty

2-14

Does not transmit voice

2-15

Does not transmit voice or tty

2-13

Incorrect scope display

2-21

(all M1 Indications except DISCRIMINATOR)

ON/OFF switch continues to trip

2-8

Receive tty malfunction

2-17

Tuning malfunction (MODE SELECTOR switch at 850 Hz)

2-19

MODEM TEST METER

Low or high REGULATED DC reading

2-12

No DC LOOP current regulation

2-21

No DISCRIMINATOR reading (RCV LEVEL reading and

2-17

abnormal scope display)

No RCV LEVEL reading (receive channel malfunctioning)

2-16

No reading

2-9

No receive DC LOOP current in mark-hold position

2-18

No 60 MA LOOP current (with 20 MA LOOP current)

2-20

No +20 volt dc reading

2-11

2-7