Yamaha security system

[BarryBid]

Does any one know why the 6Y8-02 unit has to be mounted vertically?

Just a query as the one in my Merry Fisher is on its side and the instruction moulded into the cover has been ignored.

[boscoe99]

Only the manufacturer of the unit knows for sure, but they aren't talking.

All of the Y-COP images in Yamaha documentation are clearly marked to show the device being mounted with the arrow pointed up. I suspect that the device has a sensor inside, such as an orientation sensor that is used a smart phone, a Kindle tablet, etc.. But it might have something to do with moisture protection., so that all of the wires are on the bottom of the device.

Maybe the installer was laying on his side when the installation was done. I have had to install stuff in the bilge while being completely upside down. If I were you I would simply remount the sensor assembly with the arrow pointing up.