PS-AN
There are five LED’s on the power supply unit to indicate whether any of the power supplies are
faulty. They are (from left to right):
3 o v
Station Logic Supply
2 o v
Relays and Station A-pair Supply
Crosspoint and Amplifier Supply
Amplifier Bias Supply
5 v
Main Equipment Logic Supply.
3.2.3
Stations
Station A and B pairs are accessed at the 605 plug pins. The voltages measured on each pin should be
within limits shown on table 3.2.3.
Station Voltages: A-PAIR
B-PAIR
Standard Telephone Stations
(On Hook): Without
With
WIRE COLOUR
605 PLUG PIN
W T
2
BL
6
1
BK
5
W T
2
BL
6
W T
2
BL
6
VOLTAGES
REF A
REF B
32
8V
REF
+ 50 6V
REF
Table 3.2.3
STATION VOLTAGES
3.3 MAINTENANCE PROCEDURES
3.3.1
General
Due to the sensitivity of some of the components (especially MOS components) and their susceptibility to
damage by static discharge, maintenance will be limited to changeover in the case of PBA’s and
replacement of telephone parts in the case of stations. To protect faulty assemblies and items such as the
power supply, stations and the main equipment, all transports must take place in the protective containers
supplied with the new item. For return of faulty PBA’s and other items of equipment, refer to Section
3.6 (Repair Procedures).
3.3.2
Main Equipment
Any fault in the PBA’s will require replacement of the faulty PBA with a new one. No repair of the PBA is to
be carried out on site or in field depots. Any attempt to repair the PBA in the field may result in further
damage to the PBA.
Main equipment PBA’s, except the SLB-AN and
must NOT be removed from the cabinet unless
the mains power is turned OFF.
3.3.3
Power Supply
When the power supply is diagnosed as being faulty, it is to be changed over completely by disconnecting
it from the backplane and removing the unit from the main equipment cabinet.
To remove the power supply:
Disconnect the mains cord from the power socket.
Remove all boards from the main equipment cabinet (refer to section 2.5 for board handling
instructions).
Disconnect the power supply connector from the backplane.
Remove the four front panel screws fastening the power supply to the main equipment.
Slide out the power supply unit as far as it can go.
Unclip the grommet holding the mains cord to the bottom guide plate.
Pull the mains cord through the hole in the bottom guide plate and remove the power supply unit.
To install the power supply unit simply follow the reverse of the procedure set out above.
81
AN-616
ISSUE
