Voltage for ST60 knot meter?

[dstrout]

My ST60 Tri-data's speed display has slowly stopped working, as in worked intermittently to now never shows anything but 0.0 .

I read GordMay's thread:

http://www.cruisersforum.com/forums/...ing-67899.html

In it, he mentions that if you move the sensor wheel slowly, the signal line should flip from 0 to about 8V as the magnets pass the hall effect sensor.

My question is how much voltage should be going to the sensor? If I put a meter between power and ground of the speed meter port on the back of the Tri-data, I see 4 -5V.

What should it read? My instinct is whatever boat supply voltage is (~12.7). IS that correct?

I tried his test of powering the sensor and putting a meter between signal and ground, then turning the wheel slowly. I don't see anything, but I don't know if that is because the supply voltage is low or because the sensor is broken.

thanks,
Dave.