6.7 Removing and Replacing the Lightpipe PCB
6.7 Removing and Replacing the Lightpipe PCB
The DECmpp 12000 and DECmpp 12000–LC DPUs use identical lightpipe PCBs.
However, the bracketing and mounting locations are different and the method to
access them differs somewhat.
6.7.1 DECmpp 12000/Sx Lightpipe
In the DECmpp 12000 DPU, the lightpipe is mounted to the inside surface of the
front door. Follow these steps to remove and replace the lightpipe.
1.
Turn the DPU circuit breaker OFF.
2.
Open the DPU front door. The lightpipe PCB is mounted to the inside surface
of the front door.
3.
Disconnect the lightpipe 50-pin ribbon signal cable, control panel cable, and
power cable.
4.
Loosen but do not remove the four screws that secure the lightpipe PCB
bracket to the door.
5.
Lift the lightpipe PCB bracket up and off the mounting studs and screws.
6.
Put the replacement lightpipe PCB into position over the mounting studs and
screws, checking the alignment of the lightpipe and the lightpipe cutouts in
the door.
7.
Secure the bracket of the replacement PCB to the door by turning the four
screws. Do not tighten; the PCB should be able to be moved slightly.
8.
Connect the lightpipe power supply cable, control panel cable, and the 50-pin
ribbon signal cable to the lightpipe PCB.
9.
Turn the PDA circuit breaker ON.
10. Place the lightpipe LED test switch in the TEST position.
11. Fine tune the alignment of the lightpipe and the cutouts in the door to ensure
maximum light transmission through the cutouts.
12. Tighten the four screws securing the PCB bracket to the door.
13. Place the lightpipe LED test switch in the NORMAL position.
14. Close the DPU front door.
6–20 Removal and Replacement Procedures
