Repairing An Ntbx63Aa Cooling Unit On The Bench Top - Nortel North American DMS-100 Instruction Manual

1-46 Trouble locating and clearing procedures (continued)

Repairing an NTBX63AA cooling unit on the bench top

Application
Use this procedure to repair an NTBX63AA cooling unit on the bench top.
Check for a fault with any of the front three fans. Do the check while the unit
remains in the ISDN line concentrating equipment (LCEI) frame. If a fault
exists, you can repair the unit while the unit remains in the frame. Check the
air flow sensors on the front three fans while the unit remains in the frame.
A fault in a NTBX63AA cooling unit results from one of the following:
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Definition
The cooling unit provides forced air to cool the cards in the line card drawer.
Common procedures
There are no common procedures.
Action
This procedure contains a summary flowchart and a list of steps. Use the
flowchart to review the procedure. Follow the steps to perform the procedure.
297-8021-544 Standard 14.02 May 2001
a loose or broken wiring harness
a fan motor has faults
a switch of the air flow sensor has faults