Whelen 295HFSA1 siren problem

[dpd4703]

Just got around to replacing a PA300 in our mobile CP (old DFR 1997 Wheeled Coach Type I) with a Whelen 295HFSA1 that I purchased on ELB a good while back. When switched "on" the sci-test does not light up, but the PA and radio rebroadcast work fine. When the airhorn or siren tones are activated I get a slow but steady "popping" sound through the speaker and the spkeaker 1 light flashes as the popping sounds.


Any ideas where I went wrong installing or do I have a bad siren? I used the existing wiring from the PA300 install. I am unsure if the siren brake or aux enable wires were capped and will check that when I go back in tomorrow. Thanks for any help...

 

[js_installs]

Are you running 100 watt or 200 watt ? If im not mistaking if the speaker light is flashing


that indicates an electrical shortage in the speaker wiring .

 

[acousticman]

it is possible that the voice coil is partially shorted. With a slight misalignment, the coil rubs the magnet and turns short. This will work somewhat with the PA300, but the Whelen looks at the current drawn by the speaker and indicates a short. I think this is your problem as you say it "pops" and flashes, a full short there would be no sound. You might be able to determine this with an ohm meter, a good voice coil will read about 5 ohms, d.c. any lower and there are shorted turns. A visual inspection of the coil will verify this. In my previous life as a communications maintenance tech, I saw this type of failure. Got pretty good at field repair of siren drivers.


Now, I am not sure if the Whelen will show a short for one side of the speaker wire insulation being cut and shorted to the vehicle frame, they came out after I stopped doing that type of work.