Troubleshoot Eagle Ultra Classic Speed sender

[foxden]

I have an older Eagle Classic Ultra Fish finder that has been very reliable for years. Recently the speed sensor no longer appears to work. The display reads 0 MPH. The sender spins freely but does not indicate a speed. The temperature sensor on the same sensor and cable does work fine.

I do not know how to determine if it is the spinning pinwheel sensor or the unit itself. I can purchase a new sensor but that would be a waste if mine is not faulty.

Any ideas?

 

[foxden]

I posted this last year. Never heard from anyone. I never replaced sensor but would if I could somehow test it. Any ideas this year?

 

[gm280]

I have absolutely no knowledge of how those things are setup on your boat so I looked up your Eagle Classic unit and read some of the owners manual to see if I could help out. Seems the temp sensor and the speed sensor are together in one unit and the actual transducer is separate. However, the wiring that comes from the temp/speed sensor plugs into a "Y" connection with the transducer to go into the back of the head unit. If the cabling looks real good at the actual speed wheel unit and you see no cuts or abrasions or even pinched wires, I would look closely at where the plug goes into the mating plug on the cable harness for any possible corrosion or possible wire issues (again pinches, abrasions, cuts etc.). And it that inter wire connection looked good, I'd ohm out the connector to the plug at the head unit to verify the wire is good. If those wires test good, then I'd remove and see if you can open up the speed wheel unit to read from there to the inter cable plug again looking for possible corrosion, cuts, abrasions etc. If all that checks out good, it has to be in the head unit itself. You could even have somebody spray either water or air on the speed wheel to verify the wires at the head unit are changing as well. But rule out everything else before buying anything. Throwing parts at a problem is the worst troubleshooting method ever devised... Verifying your true problem is the cheapest method yet! I also see you have both the speed and distance from your starting point displayed. I'm assuming neither of those are displayed properly. What does your voltage read on the unit? if it is less then 11 volts, you have a voltage problem that can make everything suspect and that needs to be fixed first per the owners manual... Hope this helps a little...

 

[dingbat]

Speed sensors are far from robust. My money is on the sensor being bad.

The speed sensor is as simple Hall effect sensor. Testing it is as simple spinning the sensor and looking for the output to "pulse". Just need to determine which two pins to check between.

 

[dingbat]

I can't find a schematic for your transducer but all I've found have spd outputs on pin 2 and 7, powered by pin 3.

 

[foxden]

The wiring is sound and corrosion free. I have disconnected the plug that goes to the sensor (temp and speed) but didn't,t know what to measure. Would I see some voltage from two of the four pins when it is spinning? I read about the Hall effect of the magnet but did not truly understand what I would see if the speed sensor was good or not. I agree that swapping parts isn't the best way to go do I am hesitant to buy another sensor. It is more of a desire to have things working properly. I actually can read speed (over land) on the gps.

 

[foxden]

Voltage is 12.3 so it's strong and as mentioned distance travelled remains at zero since the speed is zero, too. The temperature part works fine though.
Thanks for the advice. I do appreciate it.

 

[gm280]

If you know how to use a DVM or any other type voltage or ohm meter, go to the pug connection and read on the two pins 2 and 7 like dingbat suggested. Connect the meter and try the voltage scale first and have somebody speed the wheel while you look at the meter and see if it makes any voltage. It will probably be in the millivolt or even microvolt range. If that does seem to work, try the ohms scale and repeat the spinning of the wheel to see if anything changes. If there is no change or even some type resistance reading, I would suspect the speed unit. If you do read any type change on the meter, your head unit is the problem... JMHO!

Even a hall effect setup has to have a coil of wire to read the spinning wheel to transfer the voltage/frequency to the head unit to change/ decoded to speed and distance. So if there is no change or even a resistance of the coil reading in ohms, it has to be open... I highly doubt it being shorted, being there is really not any serious voltages involved...

 

[foxden]

Thanks, that's what I sort of did. I unplugged,the sensor from the y where it joins the transducer. It has 4 prongs. I read a resistance across two of them. Likely the thermistor that does work and gives the temperature. No other readings could be had. Interestingly enough when I just touched the leads going into the depth sounder with my finger, I would get mph readings, so somehow the head unit is,processing information, or at least that's my theory. Also, there is an output voltage coming from the head unit which is supposed to power the Hall Effect chip which leads me to think the head is working ok.

I just ordered a new sensor(old stock) and should have it next week. If that doesn't do it, I will quit obsessing and just use the gps for speed. There is just that little something in me that wants things running correctly.

Thanks everyone. I will post the results next weekend when I install it.

 

[ondarvr]

I wouldn't put any money into a unit more than a year or two old, marine electronics don't tend to age well and can die at anytime, so the money is waisted.

New and better units get cheaper all the time.

 

[foxden]

The sensor was $20, and it will avoid my having to dismount a remount a new unit. I basically use it to keep track of the depth in my flats boat. So, for me, fixing it is my first choice.

 

[gm280]

foxden, it sounds like you made a wise decision. Please take the time and update us so others with similar issues can see the outcome. That IS what these forums are really all about... I'll be watching for certain... I'm just that way!

 

[foxden]

The part is in Wisconsin on its way to me in Florida. I will post my success or failure late next week. Thanks for all the advice.

 

[foxden]

Here is the update as promised. New Speed/Temperature Sensor arrived last night, way earlier than I expected. Tested it out this morning and it works Great! The Hall Effect Chip in the old one must have gone bad or there is corrosion somewhere I couldn't detect. Anyway, I am happy.

 

[gm280]

Here is the update as promised. New Speed/Temperature Sensor arrived last night, way earlier than I expected. Tested it out this morning and it works Great! The Hall Effect Chip in the old one must have gone bad or there is corrosion somewhere I couldn't detect. Anyway, I am happy.

Glad to hear that and equally glad you took your time to report what your results were too. That makes for other to read and learn from... Happy boating! :thumb: :thumb:


After thought: You can now take apart the old speed sensor and see what really happened with it. That would be interesting to me...

 

[foxden]

It doesn't come apart, the chip is epoxied into the unit keeping it, theoretically, water tight. I might fool with it, though.

 

[gm280]

It doesn't come apart, the chip is epoxied into the unit keeping it, theoretically, water tight. I might fool with it, though.

Maybe you don't understand correctly. It DOES come apart. I mean it is toast and I'd take a very fine Dremel blade hand saw and carefully cut it open to see what was the real problem. If it is merely some corroded connections, fix it and it could come in handy later on... I always have to take things apart to understand what is inside of them. Just the way I work... :facepalm: