Replace a Timing Distribution unit (TDU1)

Electrostatic Discharge (ESD)

Observe and follow all ESD instructions while handling Tellabs plug-in equipment.

Caution! The Tellabs plug-in equipment uses semiconductor devices that can be damaged by electrostatic discharge (ESD). Do not remove a plug-in from a protective packing box or equipment rack until the time of installation or replacement. To equalize the static charge on the plug-in, establish a body path to the ground using an ESD wrist strap connected to an ESD ground. [If storing or shipping the plug-in becomes necessary, place the plug-in in a conductive shipping box to prevent static buildup.]

Apply the following precautions:

• Use grounded wrist straps, table mats, floor mats
• Handle static-sensitive devices in the nonconductive areas
• Place static-sensitive cards into an antistatic plastic bag    
• Use protective ESD-sensitive packing and shipping bags when returning repairable components

Procedure

To replace Timing Distribution Units (TDU1s):

1. If not already open, open the cover of the Tellabs 1150 MDS5 OLT (see Figure 17).

Figure 1: Tellabs 1150 MDS5

2. Locate the failed TDU (TDU A or TDU B) in the MDS5 shelf.
3. If composite clock inputs are installed, use a small flat-bladed screwdriver and carefully loosen the captive connector mounting screws and remove the composite clock (CC A, CC B, and/or CC O) connectors that have wiring attached from the TDU faceplate (see Figure 2).
    

   Note: Remove only those connectors that have composite clock wiring connected.

Figure 2: TDU Composite Clock Connector

4. Rotate the connectors, with wiring, out of the way to allow access to the TDU.
5. Rotate the upper and lower card ejectors to eject the TDU from the backplane connector.
6. Remove the TDU and place it in an approved ESD protective package.
7. Unpack and inspect the replacement TDU card for any apparent damage (see Figure 3).

Figure 3: Timing Distribution Unit (TDU1)
 

8. Using a small flat-bladed screwdriver, remove the CC A, CC B, and/or CC O connectors from the replacement TDU faceplate.

   Note: From the replacement TDU, remove only those connectors that were removed in Step 3.

9. Install the connectors removed in Step 8 on the TDU removed in Step 6.
10. Carefully insert the card into the upper and lower card guides until the card contacts the backplane connector. Then apply equal pressure on both upper and lower ejectors.
11. Using a small flat-bladed screwdriver, carefully tighten the two captive screws on each connector to secure the connector to the TDU faceplate (see Fig. 18).
12. Upon insertion, the STAT LED illuminates RED while performing internal power-up diagnostics. Upon successful completion of the power-up diagnostics, the STAT LED blinks GREEN at a 0.5-second interval while initializing. Upon completion of initialization, the STAT LED illuminates solid GREEN.

13. Did the STAT LED sequence described in Step 12?
    • If YES, go to Step 14.
    • If NO, remove the card and replace it with a known good unit.
14. Reconnect the composite clock connectors removed in Step 3 to the replacement TDU.
15. When the composite clock connectors are reinstalled, the EXT TIM LED illuminates GREEN, indicating that timing synchronization has been achieved.
16. Did the EXT TIM LEDs illuminate as described in Step 15?

• If YES, STOP. YOU HAVE COMPLETED THIS PROCEDURE.
• If NO, check the polarity of the composite clock connections. Go to Step 17.

17. Were the composite clock connections incorrect?

• If YES, STOP. YOU HAVE COMPLETED THIS PROCEDURE.
• If NO, replace the TDU that is not operating correctly with a known good unit.