TM 11-7440-232-12/ NAVELEX 0967-LP-275-5010
Section IV. TROUBLESHOOTING
5-11. TROUBLESHOOTING PROCEDURES
The Digital Data Modem MD-701(*)/UY is provided with alarms and other malfunction indicators. Usually an alarm
will be the first sign of trouble. The Modem Components and Test Equipment Table 5-2 will be used in conjunction with
the troubleshooting charts.
To begin troubleshooting, you select the correct malfunction description (para. 5-17) and go directly to that chart.
You should then perform the first test or inspection step listed under the malfunction. Depending upon your results, your
next action is given in the indication column. Often you will be directed to an additional test or inspection in the remarks
column. A series of tests and inspections may be required to identify and correct the trouble.
5-12. USE OF PMCS TABLE
The PMCS Table in Section III of this chapter, may be used in troubleshooting the digital data modem, or in
reestablishing service after a shut-down.
5-13. ERRORS LIGHT
ERRORS light, will flicker intermittently in normal operation. Increased flickering over a period of time is an
indication of reduction in performance. To determine whether performance is adequate, use the PMCS table.
When the ERRORS light remains lit, the receive branch is not working and an alarm will be given.
5-14. ADDITIONAL TROUBLES
This manual cannot cover all the troubles that may occur, nor all tests or inspections and corrective actions. If a
trouble is not listed or it cannot be corrected by performing the corrective action, refer to higher level maintenance.
5-15. MODEL DIFFERENCES
Numerous differences exist between the models of the MD-701(*)/UY. Take care to observe the differences noted in
many instructions in the troubleshooting chart.
Also, sound and sight alarms and some indicators are not included in all models of the digital data modem and may
or may not be provided in peripheral components of the system in which the modem is used.
5-16. ALARM CUTOFF
This paragraph applies to models MD-701AIUY and MD-701BIUY only.