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ST-60 Speedlog issues
02-27-16, 11:31 AM
Post: #1
ST-60 Speedlog issues
We recently had our display returned from the maximum-flat-price repair. It appears fully renovated - without taking it apart, it appears the only original parts left were the outer shell.

That's good. But...

We have an RP-65 hand-held remote for our autopilot; it has light level selection as one of the keys. That previously translated to the speedlog. However, there is no effect on it now, and it appears that if there is any backlighting at all, it's at the minimum.

Secondly, we remove our impeller at anchor when we're not cruising (not when we're just stopped for a day or two), clean it, make sure the impeller itself moves freely, and reinstall as we're leaving. We have two adjacent to each other, the second being a Signet unit which came with the boat.

Both, for whatever reason, did not read initially. The Signet has started to register after about 40 hours of cruising time. The ST60 still shows zero.

I suppose it's possible I did not properly reattach the 5 wires, or there's some issue with SeaTalk. The SOG repeats from the GPS, which is through the C120MFD, so I expect that the SeaTalk connection works.

Ideas on either problem? How to troubleshoot the impeller without removing it?



Skip, off Green Turtle Cay, Bahamas
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03-02-16, 11:17 AM
Post: #2
RE: ST-60 Speedlog issues
If the backlight level isn't translating it is usually a Seatalk bus issue. Troubleshooting is checking the connections on Seatalk bus from RP65 to Speed display.

I have enclosed the speed transducer test. I would be recommended to test, when you can remove the transducer from the water.

Testing the Speed Sensor:

Verify that the transducer’s paddle wheel is free of marine growth and rotates freely on its shaft
Power down the instrument
Disconnect the GREEN and SHIELD transducer leads from the instrument display or instrument pod.
Connect a multimeter to the GREEN and SHIELD transducer leads and configure the multimeter to measure continuity or resistance.
Slowly rotate the transducer paddle wheel by hand. Note that as the paddlewheel is rotated, the multimeter should alternate between an open circuit and a closed circuit with each quarter turn. As such one complete revolution of the paddle wheel should open and close the circuit four times.

Should the multimeter respond as indicated above, then the speed sensor element of the transducer would be deemed functional. If not, then the transducer has failed and should be replaced.
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06-21-16, 12:56 PM
Post: #3
RE: ST-60 Speedlog issues
When I took it apart for testing continuity, one of the legs came off with no resistance.

I could not get it to measure on the leads (corrosion?) but after firmly remounting those legs, it registered the transducer speed.

It's bright out so I've not had a chance to check the seatalk bus, but the remote is 3-wire and works in every other mode, so I presume that part is proper.

The other, I traded seatalk ports and made sure it was firmly seated. That may also cure the light-adjustment from the remote.

Thanks for the method.


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06-21-16, 02:03 PM
Post: #4
RE: ST-60 Speedlog issues
You're welcome.
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