Owner’s Manual
MD150 User Manual
Page 14
8 Troubleshooting
1. No display:
• Check DC power connections and DC polarity
with voltmeter. Voltage must be between 10.7
and 16.6 volts.
2. No speed reading:
a. Under normal operation, the life of the paddle
wheel is 2 years. Replace if worn. (See
Section 3.2 for replacement part.)
b. Remove speed impeller from thru-hull fitting,
spin paddlewheel manually and check for
reading.
c. Check for fouling on paddle and thru-hull
fitting.
d. Check for break in cable.
3. Low or high speed reading:
a. Check calibration.
b. Inspect for damage to paddlewheel or fouling
of fitting or paddle.
4. Erratic speed reading:
a. Is there clear water flow over paddlewheel?
b. Is paddlewheel aligned fore and aft correctly?
c. Is paddlewheel clean and turning freely?
d. See section 3.2 for replacement parts.
5. Erratic readings when engine is running:
To isolate problem, unplug the impeller. If the problem
goes away, reroute the cable away from the engine.
If problem persists:
a. Add feed-through filter capacitor on the
positive terminal of the ignition coil.
b. Add alternator whine filter to alternator.
c. Replace spark plug with resistive type.
6. No, or inaccurate temperature reading:
Remove, inspect and clean transducer if needed.
Measure resistance between pins 1 and 4 on
connector. Transducer is defective if shorted or open.
a. Check calibration.
b. Check for break in cable.
7. Speed cable is not long enough.
• Use EX345 optional cable. A maximum of two
cable can be connected.
8. No depth reading (- -) at all depths:
a. Check transducer for growth or multiple coats
of paint..
b. Check the transducer cable for cuts and sharp
bends.
c. Substitute the transducer with a known good
transducer hold it over the side of the boat into
the water and see if the instrument functions.
This isolates cause of problem (transducer or
cable.
9. Erratic depth readings (while moored):
• Check transducer for growth or multiple coats
of paint.
10. Erratic depth readings (while underway):
• Cavitation (air) under the face of the transducer.
Review installation and reinstall if necessary.
11. When power is applied display digit
counts up or down:
• See the section on Simulation Mode.
12. Simulation Mode:
• At power up, if all the segments display for 5
seconds then the instrument is in simulation
mode.
