Specifications

FTB 312-4 Revision 4 – 1-8-2008 23
The sync signal is a pulse and difficult to
evaluate with a meter. You can detect the
sync pulse as an instantaneous movement
of the meter indicator. A digital meter with
a max-min function may capture part of
the pulse. This is generally a sufficient
indication of a pulse being present. (A
24V pulse of 16 ms. width might read 12V
on a 100 ms. capture time of max-min
function.)
RFI Problems
The presence of radio frequency
interference (RFI) can burn out
components; cause a light to flash
intermittently, at the wrong rate, or at the
wrong intensity. RFI can enter the light by
any wire to or from the unit. The circuits
reject or bypass RFI, but Flash
Technology cannot guarantee complete
immunity beforehand. After installation,
you may find it necessary to add external
filters or use other methods to reduce RFI
entering the equipment. To minimize
interference, ensure proper installation in
accordance with AC 70-7460, Appendix 1,
Figure 2.
Component Testing
The following procedures describe how to
check most of the unit's major electrical
components. Always make resistance
measurements with the primary power
turned off. However, you must make
voltage measurements with power applied.
Thus, for your safety, carry out all
preliminary steps such as connecting test
leads or circuit jumpers, or disconnecting
existing circuit connections with the power
off.
Capacitors
Evaluate the condition of a capacitor with
an analog volt-ohmmeter operating in the
resistance mode. The following method
assumes an instrument with a X100
resistance scale.
Place the meter leads across the terminals
of an isolated (no electrical connections to
other circuits) and fully discharged
capacitor. Observe the subsequent needle
movement.
If the capacitor is functional, the needle
initially indicates zero ohms, but soon
begins to rise to higher indicated values. A
capacitor that is disconnected from other
circuitry is defective if it does not exhibit
this behavior. The length of time it takes
the needle to reach the 1-megohm reading
(about 65% full-scale) is a measure of the
capacitance. For example, the time is
about 5 seconds for a 10-mfd. capacitor, or
10 seconds for a 20-mfd. capacitor, and so
forth.
Manually discharge the capacitor before
repeating this measurement. This test may
not detect a malfunction that occurs only
at high voltage.
A bank of capacitors connected in parallel
may be checked as a single unit. If the test
indicates a short circuit, the individual
capacitors have to be disconnected and
checked separately. A shorted capacitor is
indicated if the resistance does not rise
above zero after several seconds of
measurement.
Wiring and Cabling
Wires or cables that move repeatedly will
ultimately break. Ensure that all cables
(the flashhead cable in particular) are
securely fastened at short intervals to the
structure or other supports.
Inspection
Closely inspect the units and check the
connections against the installation
instructions. Also, a close inspection may
reveal insulation breakdown, an
overheated component, corrosion, loose
connections, faulty relays, incorrect
hookup, and so forth.