Northern Telecom DMS-100 Series Maintenance Manual page 46

4-12 Disk drive procedures
Procedure 4-8
Disk drive replacement procedure - removing the faulty disk drive
Step Description
1 Remove the front panel of the DPP. See
Figure 7-2. Once removed, put the front
panel in a safe place to avoid damage;
bending and scratching.
2 Make sure that the other processor and disk
drive are in the ONLY mode of operation.
The other processor is defined as that
processor that does not have the failing disk
drive in the same chassis.
Enter: (at the terminal)
>DISK MODE (cr)
If the disk mode is AP or BP,
Enter: (at the terminal)
>DISK MODE AO (cr)
>DISK MODE BO (cr)
3 Power down the processor side with the
faulty disk drive. Note: Leave disk drives
untouched for at least 30 seconds after
power down. Vibration during power down
may damage the disk drive.
4 Remove -48 V dc C.O. power.
5 Disconnect disk power by removing
connector plug P8 from the power supply.
297-1001-537 Standard 01.02 December 1993
CAUTION
Since all circuit assemblies in the DPP system are static
sensitive, be careful handling them.
or
Notes
Loosen the four screws located on the left
and right hand sides of the front panel;
carefully remove the front panel.
See Switch and Status Panel Operation,
Figure 7-1.
Determine the current disk operating mode:
Response = AO = A ONLY
Make the disk in the A chassis ONLY mode
if the B21 disk is suspect.
Make the disk in the B chassis ONLY mode
if the A21 disk is suspect.
Depress the O portion of the red rocker
switch in the upper left corner of the Power
Supply until it clicks into place.
Remove the -48 V dc source for the
chassis at the DMS-100 fuse panel; disk
drive in this chassis is now disabled.
Pull down gently; fold the cable back out of
the way.
(continued)
BO = B ONLY
AP = A PRIME
BP = B PRIME