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Page 10 of 12 SC-407-10 Ver. B Installation and Operating Instructions
05/07/05 CP4842C
SERVICE
This unit is designed to provide years of reliable service under even the worst conditions. Many
times there may appear to be a problem with the unit when the true problem is in the speaker(s)
or improper installation. The following chart shows typical symptoms and possible causes.
A blown internal fuse doesn't necessarily mean that the unit is bad. If a speaker or speaker lead
is shorted the internal fuse will blow before the unit is damaged. Disconnect the SPKR leads and
replace the fuse. If the siren emits a sound when in the Yelp position it is OK. Check the speaker
(s) or leads for possible shorting.
PROBLEMS
Symptom Possible Cause Check
No power or siren
output
Power switch not turned on
Bad speaker(s)
Connector loose
Internal fuse blown
Loose connection at power source
Does backlighting come on?
Do you hear a "pop" when turned on?
Is an external fuse or circuit breaker used?
Are the negative leads connected to a good ground?
No siren tone -
PA works
High Voltage Protection
Mic button stuck
Cutout activated
Cutout Polarity Option set wrong
The input voltage must be less than highest rated voltage.
Does mic button release properly?
Does the siren work when Cutout input is disconnected?
Is the CUT P option properly configured?
No PA PA volume not set properly
Selector in Radio position
Have you tried turning the PA volume control?
PA is not available in the Radio position
Distorted siren
sound
Speaker assembly loose
Intermittent Aux Input connection
Low vehicle voltage
Is the speaker bell or tip loose?
Is the Aux Input used and wired properly?
Input voltage must be greater than lowest rated voltage.
Intermittent siren
tone
High Voltage Protection
Connector loose
Bad power connection
Mic button activation
Circuit breaker in supply connection
Is the vehicle voltage regulator working properly?
Is the connector tight on the back of the unit?
Is there a loose connection on a power lead?
Is something lying on the microphone?
Is a circuit breaker used with at least a 50A rating?
Horn function
or
Manual or Phaser
stuck on
Horn switch stuck
Man/Phsr switch stuck
Aux Input improperly connected
Aux Input Polarity Option set wrong
Does the horn switch return fully when released?
Does the Man/Phsr switch return fully when released?
Is the Aux Input used and wired properly?
Is the AUX P option properly configured?
No Radio Unit not connected to radio
Radio volume too low
Is the radio connected properly to the unit?
Can you here the radio in the vehicle?
Have you tried turning the RAD volume control?
Wrong siren tone Two-Tone option installed
Aux Input set to wrong function
Is the T-T option jumper cut?
Is the AUX I jumper configured properly?
Phaser not work-
ing
Phaser disabled Is the PHSR option jumper cut?
Horn not working Horn disabled Is the trace cut that disables the Horn switch?
Automatic Siren
not working
Siren Control in RAD position
Automatic Siren disabled
Is the siren set to the RAD position?
Is the lead cut between the lever switch board and the
siren board?
Automatic Siren
works in all posi-
tions
No power to lever switch board Do the lever switch indicators light fully?
Do the lights work with the lever switch on?
Lever switch not
working at all
No power to lever switch board
No ground at siren connector
Do the lever switch indicators light?
Does the siren work?
Lever switch not
working in some
positions
Loose output connection on lever
switch lead
Does the lever switch indicator work in those positions?
Rocker switch not
working
No power to rocker switch
Loose rocker switch output lead
Is the corresponding fuse blown?
Does the rocker switch light when turned on?