Replacing Hardware Components
8. Remove the rearlower impeller assembly by loosening the thumbscrew at
each corner and pulling the impellerassembly straight out of the chassis. For
complete instructions,see “Removing the Rear Lower Impeller Assembly”
on page 155.
9. Using a Phillips screwdriver, loosen and remove the screwat each corner of
the circuit breakerbox. Loosen the thumbscrews at the top and bottom
edge of the box.
10. Pull the circuit breaker box straight out of the chassis.
Figure 99: Removing the Circuit Breaker Box
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Installing the Circuit Breaker Box
To installthe circuit breaker box, follow thisprocedure (see Figure 100):
1. Verify that there is no power flowing from either external power source, so that
the voltage acrossthe leads of the power cables is 0 V. Ensurethat there is no
chance that the cable leadsmight become active during the procedure.
2. For each power supply,verify that the power switch on the circuit breaker box
is in the OFF (O) position.
3. Attach an electrostatic discharge (ESD) grounding strap to your bare wris t and
connect the strap toone of the ESD points on the chassis. Make sure the router
is attached to a proper earth ground. For more information about ESD, see
“Preventing ElectrostaticDischarge Damage” on page 226.
4. Align the guide pin on the back of the circu it breaker box with the opening in
the chassis, thenpush the circuit breaker box straight in.
5. Tighten the thumbscrews at the top and bottom edge of the circuit breaker
box. Using a Phillips screwdriver, tighten the screw at each corner of the box.
6. Slide the power cablelugs for both power sources onto the terminal studs
on the circuit breaker box:
Replacing Power System Components 195