Fan Replacement - Northern Telecom DMS-100 Series Maintenance Manual

7-8 Routine maintenance
The Cooling Fans at the rear
Lubricating the fans
Since the fans have permanently lubricated bearings, they never need
lubricating or oil servicing.
Replacing the fans
Use Procedure 7-3 when replacing the cooling fans at the rear of the DPP
chassis.
Before replacing the fans
Before replacement, make sure the following conditions are met:
•
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The following are available from NT: replacement foam filters, part no.
680-7859, replacement Fan Filter PCA fuses, 1/4 amp 8AG, part no.
680-9176-001, replacement Fan Bracket Assemblies, part no. NT6M55DA
or NT6M55DD and, replacement Fan Filter PCAs, part no. NT6M56AB
(may be NT6M56AD in some units. For the Filter PCA behind the Rover
Interface Panel, use part no. NT6M56AB.
297-1001-537 Standard 01.02 December 1993
The processor with the operational fan is in the ONLY mode of
operation.
A polling session has been completed; if possible, wait for a slow traffic
period before fan replacement.
Note: 2 Fuse operation (a blown fuse) usually indicates a failure. Check the
fan and associated cabling for shorts before replacing the fuse.