Chapter 12 - Fault Finding; 12-L; Fault Clearing Procedures - Toshiba Strata DK 280 Installation Manual

Fault Finding
This chapter describes the procedures to diagnose
faults in the Strata DK280 digital key telephone
system. Faults are classified and then cleared by
replacing the malfunctioning unit and by performing
operational tests in the sequences by prescribed by
the fault clearing flowcharts in Section 12.7.
12.1 Fault Classification
A Fault Classification Flowchart is provided to ensure
that fault clearing is pursued in a logical sequence
(Flowchart 12-l).
The flowcharts assume that the fault was discovered
and reported by a digital or electronic telephone user.
All faults, therefore, are classified according to the way
they would appear at the digital or electronic
telephone.
12.2 Fault Clearing Procedures
Before attempting to clear any fault, ensure that it is in
the system and not caused by associated external
equipment, such as wiring, MOH source, etc.
IMPORTANT!
Many system features are assigned, enabled
or disabled using software entries as
described in the Programming Part of this
manual. It is very important to verify that the
system programming is correct and functional
before troubleshooting the hardware.
Initialize the system (Programs 91-9 and 03) before
testing new systems or when changing the RCTU
PCB.
Faults in the DK280 are cleared by replacing PCBs,
telephones (digital or electronic) or the power supply,
as instructed in the flowcharts.
Five symbols are used in the flowcharts, which are
identified in Figure 12-l.
Marking points of a
flowchart sequence.
Important notes affecting the
---- fault clearing procedure.
Question to be answered
YES or NO.
0
Progression TO or FROM
another flowchart location.
Letters and numbers denote
the exact entrance or exit
0
I
points.
Statement of a required
action.
/
Figure 12-I
Flowchart Symbols
The flowcharts are sequentially arranged to permit
rapid fault localization within the system. All fault
clearing must begin with the Fault Classification
Flowchart, which is arranged in the correct fault
locating sequence.
Observe the following precautions when handling
PCBs:
January 1996 12-l