Journal of the Royal Naval Scientific Service. Volume 29, Number 6 ...

270 J.R.N.S.S., Vol. 29, No. 6
FIG. 4. The Automated Microform Terminal.
test-points on the equipment but it may be
necessary to give practice at this. The BLLT
was designed to meet these possible limitations.
Basically, the BLLT is a photographic model
of an equipment (in this case the JDA radar
display). Each tray of components (i.e. each
equipment unit) was photographed, along with
the display and front controls and these were
then mounted in metal trays which were
screwed to a frame to provide a full-scale mockup
of the set. Tag-strip pins were simulated by
small metal pins driven into the tag-strips on
the photographs (there are over 500 such pins
on the mock-up). Where a particular pin functions
as a test-point, a wire was attached to the
underside of the pin and this was taken to a
diode-board which provides the test-point code
to the Automated Microform Terminal. Thus,
when the test-point is located and touched
with a probe, the appropriate waveform photograph
will be displayed on the AMT.
Fault-Finding at Component Level:
The Component Level Location Trainer
This device is at the design stage: it is
essentially an extension of the BLLT in that it
would be based on a photographic equipment
mock-up. Each and every component on the
photograph would be provided with a test-point
so that all tag-strip pins would be wired. As
with the BLLT, touching a test-point with the
probe would access data stored in the Automated
Microform Terminal, in this case voltage
or resistance readings.
FIG. 5. The Block Level Location Trainer.
Student Response Recording Facilities
A complete punched paper-tape record of
trainee activities will be taken. A sequential
log will be kept of all test-points probed during
check-out on both the Flow-Diagram Trainer
and the Block Level Location Trainer. In addition,
the trainee has an Identifier Keyboard
on which to record his diagnosis. This consists
of an array of keys each labelled with the
name of a main equipment unit (such as
' Calibrator') and a set of keys numbered one
to nine, These are used by the trainee to
indicate where he has decided the fault lies;
for example, he might punch in ' Timing Unit'
and ' 4', indicating his belief that the fault
lies in sub-unit 4 of the Timing Unit.
Future Research
There are a number of ways in which the
devices could be improved and developed but,
in the immediate future, work will concentrate
on experiments in which the devices will function
as research tools.
Performance Testing and Measurement
The devices can be used as performance
tests to define and measure those aspects of
the maintainer's task which give difficulty and
in which mistakes are common or methods inefficient.
The most valuable data here may be
gathered by studying the performance of relatively
inexperienced fault-finders who are new
to the equipment and by measuring rate of
improvement as a function of training and