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If any unit is returned for adjustment or repair, it
can be accepted only if we are notified by letter or
phone in advance of its arrival. Such notice should
clearly indicate the service requested and give
all pertinent information regarding the nature of
malfunction and, if possible, its cause.
5-2. SIREN
A.
General
Any competent electronic technician should
have little difficulty in tracing and correcting a
malfunction, should any occur. For emergency
replacement of any of the small components, care
must be used when soldering. Heat easily impairs
transistors, capacitors and circuit boards. It is
therefore advisable to use longnose pliers or a
similar heat sink on the lead being soldered.
B.
Removal for Servicing
To remove the electronic assembly, located inside
the Amplifier chassis, for servicing; proceed as
follows :
1. Remove the two phillips head screws on the
amplifier’s side which secure the cover to the
Amplifier chassis.
2. Remove the cover by sliding it away from the
chassis.
C.
Removal of Circuit Board
The Amplifier logic circuit board (top circuit board)
is secured to the chassis by four Phillips head
screws. Unplug the eleven-position connector, the
RJ45 connector, and the red and black connectors
before removing the screws.
D.
Replacement of Output Transistors
Failure of one or both of the output transistors
(Q106, Q109) is usually the result of a defective
speaker (short circuited voice coil). Rebroadcast
of the unsquelched radio or music for long periods
will also have a detrimental effect on the output
transistors, and is therefore not recommended.
Federal recommends that both output transistors
be replaced should only one device prove to be
defective. This practice will ensure long periods of
service between failures.
When installing new output transistors, ensure that
the Sil-Pad insulators are installed between the heat
sink and transistors.
Before reinstalling the repaired PA4000, make
certain that the speaker(s) is (are) not defective.
HIGH CURRENT ARCING: Do not connect this
system to the vehicle battery until ALL other
electrical connections are made and you have
verified that no shorts exist. High current
conductors can cause hazardous sparks or burning
wire, resulting in electrical fires.
E.
Testing
All effective sirens and horns produce loud sounds
(120 dB) that may cause permanent hearing loss.
Always minimize your exposure to siren sound and
wear hearing protection. Do not sound the siren
indoors or in enclosed areas where you and others
will be exposed to the sound.
After servicing is complete, perform a test of all
functions to ensure the siren is operating properly.
