6.3 Remove and Insert Line Unit (LU) Circuit Packs
OVERVIEW
This procedure provides the proper sequence(s) for removal (or unseating) and
insertion (or reseating) of Line Unit (LU) circuit packs. Unseating of all grid and
Gated Diode Crosspoints Access (GDXACC) packs is required before -48 V DC is
restored if the LU is not equipped for Line Unit Auto Power Recovery (LUARP).
Unseating and reseating in the proper sequence(s) is/are required to avoid potential
damage to certain packs that can occur when other packs are missing or not powered
up. For this reason, the following Cautions should be observed. Also, for personal
safety, observe the following DANGER.
Caution 1: Do not remove any -48 V DC fuse at the LU cabinet or at the
Power Distribution Frame (PDF) or in any other way interrupt the -48VDC
power to the LU packs as a troubleshooting technique.
Caution 2: Removal of an entire LU from service should only be done when
necessary (rarely). Once power is lost, the system may remove working lines,
marking them "OOS, MAN." These lines must be restored via Step 9 to
complete this procedure and minimize the interruption of service on those
lines connected to the LU.
Danger: Hazardous voltages are present on LU packs (even shortly after they
are removed from the cabinet). Do not touch exposed components or wiring
paths on the pack. When removing or inserting a pack, use the latch and hold
the pack at its edges without touching components or paths.
PROCEDURE
1. For LU Model 3 (J5D004AD):
a. For the entire LU, perform Step 3.
b. For a TN832(B) pack only, remove the GDXACC circuit in the SG from
service with the appropriate RMV input messages and unseat the TN831(B)
(first) and then the TN832(B) pack.
c. STOP. YOU HAVE COMPLETED THE PACK REMOVAL PORTION OF THIS
PROCEDURE.
2. For insertion or reseating of LU packs:
a. For LU Model 3 (J5D004AD):
1. For the entire LU, perform Step 3.
2. For a TN832(B) pack only, insert and latch the TN832(B) pack and (last)
the TN831(B) pack. Unconditionally restore the packs with the
appropriate RST input messages.
3. STOP. YOU HAVE COMPLETED THIS PROCEDURE.
3. Before removing/unseating any LU packs, verify that the LU’s equipment groups
(Service Group SG 0 and SG 1) and GRIDs (0-7/9) are out of service (OOS). Use
of the appropriate RMV input messages with the unconditional (UCL) option may
be required to remove the entire LU from service.
235-200-150
January 2003
CORRECTIVE MAINTENANCE
Procedure 6.3
Issue 3.00 Page 6.3-1
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