Unitrol TM4 No Siren Audio? [SOLVED]

d119

Member
May 26, 2010
291
CA - Land of Steady Red
Hey all.

Was given (yep!) a Unitrol TM4 today. Just checked it out. It has the Wail/Man/Hi-Lo selector switch on the front as well as the "BYPASS/HORN" and "SWEEP/LOCK" switches on the front.

Relays all seem to work, the air horn works nice and loud, full volume. The "ALARM" input on the back works fine, nice loud 2kHz tone as it should be. The horn ring terminal will generate a peak & hold wail as it should.

But I don't have any wail or yelp using the slide switch.

I looked at the boards (I'm an electronics tech) and can't find any evidence of damage or modification. Is there something I am missing? There is an additional wire added to an "IGN" pad on the relay (top) board. that doesn't seem to do anything.

The KILL terminal has nothing connected to it.

Any thoughts here?
 
Last edited:

d119

Member
May 26, 2010
291
CA - Land of Steady Red
Leaving this for anyone else that might encounter this. I found pin 7 of IC U2 had been cut, this basically ends up being the center pole of the Wail/Hi-Lo switch. Crafty.
 
Last edited:

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