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STROBE SYSTEM TROUBLE-SHOOTING
TROUBLE-SHOOTING PROCEDURES FOR AVIATION
ANTI-COLLISION STROBE LIGHT SYSTEMS
WHEN REPAIRING WHELEN ANTI-COLLISION STROBE LIGHT
SYSTEMS, USE ONLY WHELEN FAA APPROVED HARDWARE. BE
CAREFUL OF STROBE LIGHT PARTS THAT ARE SIMILAR IN
APPEARANCE!
The Whelen Aviation Strobe Light is a condenser discharge strobe light
system. A condenser is charged to approximately 450 volts DC, then
discharged across a xenon flash tube at controlled intervals. The con-
denser is parallel across the xenon flash tube that is designed to hold
off the 450 volts DC applied, until the flash tube is triggered by an
external pulse. This pulse is generated by a solid-state timing circuit in
the power supply.
When trouble-shooting a strobe light system, first determine if the
trouble is with the flash tube or the power supply. This can be accom-
plished by replacing the flash tube assembly with a good operating
flash tube, or with the use of a Whelen Strobe Check unit.
Whelen's power supplies are protected against a short or open circuit
on the output. In either case, the power supplies will effectively turn
themselves off when subjected to a shorted output of a xenon flash
tube that refuses to flash.
WARNING: Strobe light power supplies are meant to be used, not to
remain in an inactive state. Use them at all times, this will improve their
proper functioning. Any strobe light power supply that has been out of
service for a long period of time is subject to failure because the elec-
trolytic condenser loses the polarity formation. A strobe light power
supply not having been used for one year or longer is vulnerable to
failure, applies to
1993 & older
If this is the case, it is recommended to start operating the system on
a voltage that is reduced by 25 percent for 10 to 15 minutes before
putting the power supply into normal service. This will prevent over-
heating of the condenser while they reform. If the power supply, after
a long period of non use, is operated at full voltage immediately, there
is an excellent possibility that the condenser will become overheated.
POWER SUPPLY TEST PROCEDURES
THE POWER SUPPLY IS A HIGH VOLTAGE DEVICE. LET THE
POWER SUPPLY BLEED DOWN FOR 10 MINUTES AFTER
TURNING OFF POWER BEFORE HANDLING.
WARNING: Reverse polarity of the input power, for just an
instant, will permanently damage the power supply. This dam-
age is sometimes not immediately apparent, but will cause
failure later on.
External trigger switching is not provided on the A413A, HDA-
DF Strobe Light Power Supply (Reference A413,T3-DF old style
strobe light power supply, outlet #1). Do not short out high
voltage for extended length of time; it will cause overheating of
the output diodes and cause possible failure.
A normal operating power supply emits an audible tone. If there is no
sound emitted, investigate.
1. Determine that there is a proper input voltage at the power supply.
If this test is positive go to step 2.
2. Clear all possible shorts at the power supply, by disconnecting the
output cables from the power supply outlets, and connect an oper-
ating strobe lighthead assembly or a strobe check unit directly to
the power supply outlet, then apply the required voltage to the
power supply input. If this application proves positive the power
supply is in working condition, and the problem may be with the
interconnecting cables.
© 2019 Whelen Aerospace Technologies
units.
CABLE CONTINUITY CHECK PROCEDURES
If pins 1 and 3 are reversed, or if there is a short between pins 1 and 2
of the interconnecting cable, the power supply will be rendered non-
operable until the short is cleared. A short of this type will not cause
any permanent damage to the power supply. However a discharge of
the condenser across pin 1 and pin 3 will destroy the trigger circuit in
the power supply.
1. Check for continuity between the connectors of each interconnect-
ing cable:
Pin 1 to pin 1 (red wire = anode +).
Pin 2 to pin 2 (black wire = flash tube ground -).
Pin 3 to pin 3 (white wire = trigger).
2. Check for shorts between pins 1 and 2, pins 1 and 3, and pins 2
and 3 of the interconnecting cable.
NOTE: When pins 1 and 2, or pins 2 and 3 are reversed, the system will
appear to operate normally, but these conditions will cause early flash
tube failure, and void the flash tube warranty.
XENON FLASH TUBE PROCEDURES
1. A xenon flash tube can be very photosensitive. One will flash nor-
mally when exposed to an external light source, but may become
hard to fire when subjected to darkness.
2. They will become hard firing with age, or when exposed to a very
high temperature. A hard firing tube will sometimes operate with
the engine running, but will fail when operated on a low battery.
3. They can develop a leak through eggshelling of the glass, or a leak
can develop around the seal of the wire to the glass. This is caused
by hot and cold cycling of normal operating of the system.
4. They can go into self-ionization (continuously glow a light Blue),
thus rendering the entire system non-operational until flash tube is
replaced. This most likely occurs when the input voltage is highest.
This can be checked by turning the system off. When turning the
system back on, it generally will operate normally for a few flashes
before going back into self-ionization.
ANY OF THE ABOVE MENTIONED CONDITIONS ARE REASONS FOR
REPLACEMENT OF THE XENON FLASH TUBE.
NOTE: Installing one new flash tube in any multi-head strobe light
system, will sometimes cause the remaining old flash tube to misfire
or skip. This signifies that the old flash tube is nearing the end of it's
service life. However, to check the questionable flash tube, install it in
a system and apply a reduced voltage, approximately 20 percent, to the
input to the power supply. If the flash tube will operate at this reduced
level, it still has a great deal of service life in it.
WHELEN'S CometFlash
("CF") Strobe Light System con-
®
sists of four high energy pulses per burst of light, 45
bursts of light per light.
NOTE: Whelen Engineering does not recommend attempting to repair
their strobe light power supplies in the field. It is recommended to take
advantage of our 48-hour Repair Service.
61
Document #05131 Rev. E
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