Vista 20P slight buzzing on siren after installing AD2PI

[dyong]

I'd appreciate your collective wisdom in helping me diagnose and solve this problem:

After connecting my AD2PI device to my Vista 20P system, I noticed that the siren for the alarm now emits a faint buzzing sound all the time. And even more, if you listen carefully, you can hear some radio station in the buzzing. I believe it must be due to some line noise, but the strange thing is that it didn't occur until after the AD2PI was installed.

Terminals 3/4 on the Vista 20P go to the siren and terminals 4/5 are the aux power that go to the AD2PI and other devices. I wonder if the additional current draw or resistance created by the AD2PI did something to cause the buzzing for the siren.

Any thoughts or suggestions on how to get rid of the buzzing?

Thanks!

[trialnerror]

Don't know if this will help or not. The AC power terminals (1,2), alarm sounder terminals (3,4), and keypad terminals (4,5,6,7) where alarmdecoder connects may have some cross-connections with terminals 3 & 4? Make sure all wires are on appropriate terminals and not touching adjacent wiring.

My monitored panel was recently updated (no alarmdecoder installed yet) and when all was said and done there was a slight buzzing coming from my sounder too. The install tech didn't know what the cause was and elected to install a new sounder (only touching wiring on sounder end). That fixed the problem. No idea why.

[kevin]

You can try moving the alarmdecoder to a different location (daisy chain off an existing keypad is a good choice)

Sounds like some sort of ground loop issue or something not wired fully (loose wire or something)