SR Mariner Knot meter

[PatrickML]

My boat came with an old SR Mariner knowmeter model KM/Z series Z91.
To make a long story short it appeared it would be easy to make it work (it was defective) and I had the head repaired as the sender/Paddle wheel seemed to work.

Once repaired the next season it seems the transmitter is now defective.
I know I can order one of these but can someone tell me how to test the head again to make sure it works - its a three wire system (Black, Red, Green.

I know I may have wasted some money but I am where I am now and prefer to get it working.

PatrickM

[kilobravo]

Patric:
The three wires of the sensor hook up: Red to +12V, Black to Ground (-) and Green is the output. Inside the sensor is one Integrated Circuit Amplifier, one Transistor and some passive components.
Measuring a signal with a voltmeter on a 12V scale should show pulses when the paddle wheel is spinning. If there is no signal check if the magnet in the paddle wheel is present.
The electronics are epoxied into the plug. It seems to be impossible to get to the inside and replace them.
Chris