intermittent Autohelm Tridata 50

[tjr818]

A few days ago our Autohelm display decided to show all zeros instead of the speed and depth. Since that information comes from two different transducers I imagine that the problem is with the ST50 itself or with the wiring, it is getting power so I am looking for ideas, has anyone experienced this? Raymarine says that they cannot help because the ST50 predates there legacy support, they have no information on it.
The next day the plot thickens, after checking connections and wiggling every wire, we were out sailing and we motored for the first 45 minutes or so. The depth gauge and and the knotmeter were both on at the beginning, but soon went blank. We flipped the Instrument switch on the panel off and then back on, both instruments returned to working. Ten minutes later both instruments went blank. We again flipped the switch off and then back on with the same results. This went on the entire time that we motored. When we shut the engine down both gauges worked for the rest of the day.
Out sailing for a third time yesterday, we motored for 20 minutes and the instrument shut off three times, we then sailed for six hours and the instruments never faulted during the sail. Any idea as to what might be going on? I am stumped. What is going on and where do I start?

[tartansailor]

This is not an answer to your problem, but the thought came to mind
that it might be a loose connection somewhere, or a crack in it's circuit board,
or something else. Hope it's something simple.
Dick

[Jim Walsh]

I'm on a par with Ben Franklin when it comes to my knowledge of all things electronic and electrical. I did have a very recent experience with my chartplotter and radar "blinking". I was immediately advised to check the ground. I cleaned the main ground connection from the boats electrical system to the engine and the problem has disappeared.
I was advised subsequently to add that to my routine annual maintenance list.

[tjr818]

I'm on a par with Ben Franklin when it comes to my knowledge of all things electronic and electrical. I did have a very recent experience with my chartplotter and radar "blinking". I was immediately advised to check the ground. I cleaned the main ground connection from the boats electrical system to the engine and the problem has disappeared.
I was advised subsequently to add that to my routine annual maintenance list.

Thanks Jim. My experience with electronics seems to always involve a few Ben Franklin$. I will check again for poor connections and report back. It just seems so strange that the problem only happens with the engine running (so far).

[mgphl52]

Thanks Jim. My experience with electronics seems to always involve a few Ben Franklin$. I will check again for poor connections and report back. It just seems so strange that the problem only happens with the engine running (so far).

Vibration with loose ground?

[Boyd]

The bad ground is a good lead.

I would add that checking the switch you mentioned is also high on the list. Those switches go bad.

Check the alternator connections. Since the problem seems to happen when the engine runs.

The thru hull sensors do go bad and the result is all zeros. Unlikely that both are intermittent at the same time.

Does your system connect to other SeaTalkI devices? If so thats a place to look. The tiny SeaTalk connectors are fragile and the wires are tiny. Check for corrosion at the connections at the back of the gauges themselves.

Those gauges use a 4 wire SeaTalkI system. If the gauge goes blank, its the power wire thats bad.

If it does come down to the gauge has gone bad, check ebay for vendors selling those used or parts. I recently got a new display for my ST60 Tridata from a vendor in France over ebay.


Boyd
s/v Cat-A-Tonic
Prout 34
Fort Lauderdale, Fla