Fans; Cleaning - Northern Telecom DMS-100 Series Maintenance Manual

7-6 Routine maintenance

Fans

There are three ventilation fans in the DPP . Two are on the rear of the A and B chassis. The third
fan is inside the DPP in the B chassis behind the Rover Interface Panel.
Cleaning the Fan foam filter
The two fans on the rear have a foam filter under the metallic screen. Clean this foam filter at
least monthly, or as conditions warrant, using Procedure 7-2. The fan blades must still rotate
during cleaning.
Procedure 7-2
Cleaning the Fan Foam Filter
Step Description
1 On the outside of the rear panel, insert a
small, flat blade screwdriver between the lip
of the filter and the rear panel sheet metal;
pry up. See Figure 7-3.
2 Remove the foam filter and gently wash in
warm water.
3 Brush off any dust from the fan enclosure
area.
4 Clean the fan filter screen with compressed
air.
5 Make sure the foam filter is completely dry
before reinstalling.
Go to step 4.
6 Place the foam filter and screen assembly
over the fan opening.
7 Repeat steps 1 - 6 for the other filter.
297-1001-537 Standard 01.02 December 1993
Notes
There are four slots on the screen
framework.
Let the filter dry.
Air flows to the interior of the DPP.
Press into place.
CAUTION
The fan must operate during filter cleaning or replacement. Do
not touch the rotating fan blades with the filter or your fingers !