User's Manual

ADCP-75-130 • Issue 3C • August 2006

Page 57

3. Connect the DC power cable to the RJ-45 circuit access tool (see Figure 28).

4. Using a DC voltmeter, verify that the DC voltage level is between 34 and 48 VDC

between any set of positive and negative (+/-) terminals at the RJ-45 circuit access tool

as shown in Figure 29. Due to source current limiting at the DHU or DEU, low voltage

can mean excess wire resistance, low source voltage, or excess remote current.

Warning: The DRU uses 48 VDC power. To avoid electric shock or burns, use extreme care

when working near exposed terminals or uninsulated cables. Be careful not to touch exposed

terminals or to cause a short between terminals when checking voltage levels.

16206-B

POSITIVE (+)

TEST POINTS

1, 3, 5, AND 7

NEGATIVE (-)

TEST POINTS

2, 4, 6, AND 8

Figure 29. RJ-45 Circuit Access Tool Pin/Wire Designations

5. Disconnect RJ-45 circuit access tool from the DRU.

6. Use the DC voltmeter to check for open pin connections by checking for voltage

between the +/– pairs on the RJ-45 circuit access tool (see Figure 29).

7. Disconnect the DC power cable from the RJ-45 circuit access tool.

8. Re-connect DC power cable to the DRU.

6.5 DHU or DEU Fan Replacement Procedure

It is recommended that the fans (catalog # DGVI-100000FAN) be replaced every five years.

Replacement of a fan requires that the DHU or DEU be turned off for a short period of time. This

will drop all existing calls, cause a temporary loss of service, and generate a major alarm. Use the

following procedure to replace the cooling fans within the DHU or the DEU:

1. Before touching the DHU or DEU or handling a fan, slip on an Electro-Static Discharge

(ESD) wrist strap and connect the ground wire to an earth ground source. Wear the ESD

wrist strap while completing each section of the fan installation procedure.

Warning: Electronic components can be damaged by static electrical discharge. To prevent

ESD damage, always wear an ESD wrist strap when working on the DHU or DEU and when

handling electronic components.

2. Observe the fans (located on right side of enclosure) to determine which fan requires

replacement. The faulty fan may be stopped, running at a reduced speed, or the fan

bearing may be noisy.

Note: Because the Mean Time Between Failures (MBTF) is the same for both fans, it may be

more efficient to replace both fans at the same time.