Northern Telecom DMS-100 Series Maintenance Manual page 223

Procedure 7-3
Replacing the Cooling fans
Step Description
1 Request a polling session from Collector
personnel.
2 Remove the front panel on the A chassis.
See Figure 7-2.
3 At the Switch and Status Panel:
a. Press the A/B processor. Select
Switch to show the same as the
processor with the operational fan.
b. Make the P/O processor Mode
Select Switch O.
c. Turn the Mode Switch to the right.
4 Remove the rear panel of the chassis to be
worked on.
5 Remove the 2 screws securing the fan
mounting bracket in the chassis. See
Figure 7-4. Support the fan assembly with
your hand while removing the two screws.
Since all circuit assemblies, disk drives, and other
hardware in the DPP are static sensitive, be cautious.
Wear a wrist grounding strap when working with the
DPP. Jacks at the lower right of the Rover Interface
panel (B chassis) and the lower right of the Switch and
Status Panel (A chassis) are provided to accept the
banana plug connection on the end of a grounding strap.
WARNING
Since the DPP is powered up during this procedure,
observe all safety procedures for operations on live
equipment.
(continued)
DPP Recovery and Routine Maintenance Guide BCS35 and up
Routine maintenance 7-9
Notes
Explain that maintenance activity is
scheduled at the DPP as a precaution.
Loosen the four captive screws on the left
and right of the front panel and carefully
remove it. Put it in a safe place to avoid
damage.
Make the processor with the operational fan
the ONLY processor if it isn't already.
See Figure 7-1.
Turn it 45 degrees to the right and release.
Figure 7-4 shows the eight screws to
remove. Save the screws.
These 2 screws are on the outside of the
chassis, in the upper left corner of the right
hand panel, as from the rear.