One day when I was making some audio recordings of some of my alarms (more on this will be for a different topic) then, I’ve noticed that my U-MMT was making some strange rattling noises. For some odd reason, this only happens when I hook it up to my BG-10 pull station when it’s not pulled. I’ve tried hooking up the light switch I have and two of my Simplex T-Bars (4251-20 and 2099-9754) to the U-MMT, and it didn’t seem to make that “rattling noise”. I’ve hooked up different alarms (34T, MT, etc.) to the BG-10 and they didn’t make any noise whatsoever.
Here is a video of an audio file (apparently since I can’t simply attach an audio file to this post for some reason) of what the rattling noise sounded like (when set to Code-3):
http://www.youtube.com/watch?v=WaevvlI3IRk
For the record, only the horn was wired up.
Does anyone know why this is happening?