16 NAVMAN M100 User Manual
Troubleshooting Chart
No display:
Check DC power connections and DC polarity with voltmeter. Voltage must be
between 10.7 and 16.6 volts.
No speed reading:
1. Remove speed impellor from skin fitting, spin paddlewheel manually and check
for reading.
2. Check for fouling on paddle and skin fitting.
3. Check for break in cable.
Low or high speed reading:
1. Check calibration.
2. Inspect for damage to paddlewheel or fouling of fitting or paddle.
Erratic speed reading:
1. Is there clear water flow over paddlewheel ?
2. Is paddlewheel aligned fore and aft correctly ?
No, or inaccurate temperature reading:
1. Check calibration
2. Check for break in cable.
No depth reading (--) at all depths:
1. Check transducer for growth or multiple coats of paint.
2. Check the transducer cable for cuts and sharp bends.
3. Substitute the transducer with a known good transducer hold it over the side of
the boat into the water and see if instrument functions. This isolates cause of
problem (transducer or instrument).
Erratic depth readings (while moored):
Check transducer for growth or multiple coats of paint.
Erratic depth readings (while underway):
Cavitation (air) under the face of the transducer. Review installation and reinstall
if necessary.
When power is applied display digit counts up or down:
See the section on Simulation Mode.
Erratic readings when engine is running:
1. Reroute power and transducer cables away from ignition wires and battery
cables.
2. Add feed-through filter capacitor on the positive terminal of the ignition coil.
3. Add alternator whine filter to alternator.
4. Replace spark plug wire with resistive type.
Simulation Mode
If the speed is not changing and reading around 10kts regardless of boat speed
then the instrument is in simulation mode.
