User's Manual

ADCP-75-130 • Issue 3C • August 2006

Page 48

6.3 Fault Isolation and Troubleshooting

Fault isolation and troubleshooting guidelines are provided in Tables 11, 12, 13, and 14. When an

alarm is reported, determine the type of alarm generated (minor or major) and then check the LED

indicators on the DHU and note any that are red, yellow, or off. If any of the Port 1–6 OK/NOK LED

indicators on the DHU are red or yellow, also check the LED indicators on the connected DEU’s

and/or DRU’s and note if any are red or yellow. Start the troubleshooting process at the DHU and then

work toward the unit where the alarm originated. The troubleshooting tables are organized according

to unit type. Locate the problem in the appropriate table, check out the suggested possible causes, and

take corrective action as required.

Figure 24 shows two basic ICS system configurations. The troubleshooting tables list possible causes

for various problems. If the cause of a particular problem is specific to either of the two system

configurations shown in Figure 24, the type of system configuration (1 or 2) will be referenced in the

table.

17962-A

FWD

REV

DRU

FWD

REV

DRU

FWD

REV

DIGITAL EXPANSION UNITDIGITAL HOST UNIT

DIGITAL HOST UNIT

(2)

(1)

Figure 24. ICS System Basic Configurations

Table 11. DHU Fault Isolation and Troubleshooting Guidelines

Alarm Type LED LED COLOR

Minor UNIT Yellow

Problem : The DHU is overheating.

POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS

1. Air intake or exhaust openings to DHU

chassis blocked.

2. Ambient temperature > 50º C/122º F.

3. Faulty fan.

1. Remove cause of air-flow blockage.

2. Reduce ambient temperature.

3. Replace fan (see Subsection 6.5).

Alarm Type LED LED COLOR

Major UNIT Red

Problem : The DHU detects an internal circuitry fault.

POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS

1. Faulty DHU. 1. Replace DHU.

(Continued)