Adapting CanDooPro digital GPS speedometer for NGI display on Polaris MSX hulls

[K447]

I have a 2003 Polaris MSX140 whose speedo doesn't work. All other gauges appear OK and the ski is otherwise in good condition.

I have performed the test on the paddlewheel as set out on page 7.7 of the MSX140 Service Manual. At rest, my ohm-meter shows an open circuit and when I spin the paddle wheel (by hand and with compressed air) the reading doesn't change.

I have a spare paddle wheel which was removed from a ski in which the speedo worked just prior to de-commissioning the ski 3 years ago. Bench-testing that paddlewheel yielded the same result as above.

I wonder whether these units lose their efficacy through non-use. Some paddles on the de-commissioned paddlewheel show signs of retained magnetism; however, I'm not sure how relevant that is to the component's operability.

...

The paddle wheel sensor is a Hall Effect sensor. It is powered by a low current voltage source from the display. As the magnetized paddles pass the sensor the sensor changes resistance, creating a pulse that the dash senses. Pulse counting creates a speed reading.

The polarity of the test voltage applied to the sensor wires matters. If your ohm meter has opposite polarity at the probes or the voltage is out of range for the sensor then the sensor will not work.

[bspanovic]

Hi Swan, I have a msx140 speedo that I don't need. I think it works but I have never tested it as I don't have MSX. Yours for aussie $30 if you like.

[swan]

Thank you bspanovic, I will PM you.

[swan]

Thanks, K447.

When I tested the de-commissioned paddlewheel in a ski (today), it appeared to work alright. Not sure what I did wrong with my multi-meter test of the paddlewheel alone!