C H A P T E R  12

Accessing the System

This chapter states the antistatic precautions that must be taken before working on the Netra 20 system.

The chapter contains the following sections:

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Caution - The plug at the end of the AC power cord is the primary means of disconnection for the Netra 20 AC system.

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Caution - To isolate the Netra 20 DC system, open all external circuit breakers.


To perform the removal and fitting procedures described in this part of the manual, you will need the following tools:


The following components can be accessed while the system is in the rack:

Access to all other components requires removal of the top cover. This is a service operation and is covered in the Netra 20 Service and System Reference Manual

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Caution - Owing to the weight of the unit, two persons are required to remove the unit from and replace it in the rack.

Antistatic Precautions

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Caution - Wear an antistatic wrist strap and use an ESD-protected mat when handling components. When servicing or removing system unit components, use an antistatic wrist strap with a 10 mm press stud connection and attach the antistatic wrist strap to the press stud at the rear or front of the chassis before removing the top access cover.


Attaching the Antistatic Wrist Strap

single-step bulletTo attach the antistatic wrist strap to the chassis, connect the strap as shown in FIGURE 12-1 or FIGURE 12-2.

 FIGURE 12-1 Attaching the Antistatic Wrist Strap to the Rear of the Chassis

 FIGURE 12-2 Attaching the Antistatic Wrist Strap to the Front of the Chassis

Front Fascia

The detachable front fascia houses the optional air filter and is fastened to the system chassis at the bottom edge by two plastic tethers. You need to detach the fascia completely only to change the filter (to avoid dust from the filter being sucked back into the system); you can carry out all other procedures by lowering the fascia and leaving the tethers attached.

 FIGURE 12-3 Front Fascia and Filter

Removing the Front Fascia

Caution - Exercise care when opening the fascia. You must detach the plastic locating pegs on the bottom edge of the fascia before lowering it.

1. Pull the fascia away from the top of the chassis not more than 2.5 cm (1 in.) using the finger hold in the middle of the fascia.

2. Lift the fascia forward and off the locating pegs on the bottom edge of the fascia.

3. Swing the fascia forward and down so that it hangs on the two plastic tethers.

Detaching the Fascia Tethers

4. Squeeze together the sides of each plastic tether and pull it from the system chassis.

5. Similarly, squeeze together the sides of the tether to detach each locating pin in turn from the retainers on the fascia.

Fitting the Front Fascia

Follow Step 1 through Step 5 if you are refitting the tethers to the fascia, otherwise start at Step 6.

1. Insert one side of the locating pin on the tether in the retainer on the fascia.

2. Squeeze the sides of the tether together to insert the other locating pin.

3. Repeat Step 1 and Step 2 for the other tether.

4. Insert the other end of one of the tether in the corresponding slot in system chassis.

If the tether is a tight fit, squeeze the sides of the tether together.

5. Repeat Step 4 for the other tether.

6. Swing the fascia up until it is nearly vertical and insert the locating pegs on the bottom of the fascia in the slots on the system chassis.

Caution - Do not swing the fascia forward once you have inserted the locating pegs or they may break.

7. Press the top of the fascia forward until the catch on the fascia clicks into place on the system chassis.

Air Filter

If required, you can replace the black mesh screen located behind the front fascia with the optional foam air filter and metal retainer supplied with the system (see FIGURE 12-3). Clean or replace the filter regularly to maintain the airflow through the system.

Caution - To ensure that dust is not sucked into the system when you replace the filter, remove the fascia completely from the system before proceeding.

Removing and Fitting the Mesh Screen

1. Detach the front fascia and place it on a workbench away from the immediate vicinity of the system.

See Removing the Front Fascia.

2. Press the two catches on the mesh screen and lift that side away from the fascia.

3. Carefully disengage the two tabs at the other side from the fascia and lift out the screen.

Take care that you do not damage the plastic locating lugs when you detach the screen.

4. Continue with Step a or Step b, as required.

a. Replace with a foam filter and retainer as described in Step 4 through Step 6 in Replacing the Filter.

b. Continue from the following step to replace the screen.

5. Insert the locating tabs one side of the mesh screen into the corresponding slots on the fascia.

6. Carefully swing the other side down until the catches on the screen engage with the fascia.

7. Re-attach the fascia to the system chassis.

See Fitting the Front Fascia.

Replacing the Filter

1. If you have not already removed the front fascia, detach it and place it on a workbench away from the immediate vicinity of the system.

See Removing the Front Fascia.

2. Release the two clips securing the filter retainer and lift it from the fascia.

3. Remove the filter and carefully dispose of it.

4. Clean the fascia to remove any remaining dust.

5. Insert a new filter and secure it with the retainer.

6. Re-attach the fascia to the system chassis.

See Fitting the Front Fascia.