Publication Number 53719. Issue 3, April 2012
SERVICE MANUAL FOR THE 13754 TGX150 INTERNAL RLAN TYPE A/B SC ETM
Page 63
8
FAULT FINDING AND TESTING
8.1
GENERAL INFORMATION
Although the ETM is designed to be both extremely reliable in operation and virtually
maintenance-free, it is inevitable that the occasional fault may occur. This chapter explains how
to diagnose and rectify some of the more likely problems that may occur. In addition, sufficient
information is given to help the user to trace any faults that are not mentioned. It must be
emphasised that the instructions given here are intended solely for personnel working at Levels
2 and 3, as defined in Paragraph 5.2.
When diagnosing faults, begin by referring to Table 4 and then turn to the reference quoted for
the fault in question. This reference will give one or more possible causes for the condition,
beginning with the most likely or simplest one. It is assumed that the faults are genuine and do
not arise from incorrect installation or operation. If in doubt, check the operating instructions.
A number of fault conditions may be caused by defective connecting wires and cables, and
Paragraph 8.3 explains how to test cable assemblies as part of the fault-finding process. No
repair instructions are given for the printed circuit boards because attributable faults can be
cured simply by replacing the board and returning the old unit for repair.
Some failure conditions may be signalled to the operator by a message on the machine's display.
Since the exact nature of these messages will depend on the machine's programming, they are
only mentioned in this chapter in the most general terms.
The removal, disassembly and refitting of components are dealt with in detail in Section 7, and
the following paragraphs make frequent reference to the appropriate parts of that section. This
is done to avoid the needless repetition in these instructions of a set of basic procedures.
Note: Plugs, sockets, and other components on the circuit boards may be identified by
referring to Figure 28.
