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CAUTION
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The power supply is powered from a 240V mains supply and hazardous
voltages are present within. Ensure that the mains cord is disconnected from
the mains before removing the power supply unit. Do not attempt to repair
these units.
3.3.4
Stations
Maintenance of the stations will be confined to the replacement of transmitter and receiver inserts, cords,
plugs, power-fail dial boards, Headset interface and sockets. Faults in the
within the station or with
the pushbutton assemblies will be rectified by replacement of the station completely.
3.4 FAULTFINDING PROCEDURES
3.4.1
Board Swapping
Board swapping can be used to confirm a faulty board diagnosis when the suspect board is duplicated in
the system. This applies in particular to the line/station interface and two-wire internal extension boards.
Take the suspect board and swap it with an identical board. If the fault follows the suspect board then it is
faulty, otherwise the fault is located somewhere else.
3.4.2
Flow Chart Symbols
The diagnostic flow charts may be used whenever failure occurs. They are a means of
a fault
occurrence in one of the printed board assemblies
in an established working system.
Always commence at the “Start” block.
Flow Chart Symbols:
Decision Function:
This block contains a question which may be answered only by a “YES” or a “NO”. ONE ONLY of its two
outward paths may be taken, depending upon the answer.
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YES
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NO
Action/Operation:
This block contains instructions defining an action to be taken (e.g. board replacement) or a test to be made
(this will precede a decision function). It is essential to comply exactly with the instructions.
ACTION
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AN-61 6
ISSUE
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