Auto helm ST-50 depth sounder trouble shooting

[martyk]

Hello all,

New to the forum and looking for help trouble shooting my depth sounder problem. Away from the boat for two months to find my depth sounder now reading 2.2' regardless of depth. I started with cleaning the ducer face with no change. next I purchased a new 200khz? airmar transducer from local supply and made temporary connections to the two pin connector cut from the old ducer lead. With the new ducer held in the water beside the boat it still yields the 2.2' reading. The depthsounder is part of a complete multi and tri-data system the balance of which still works so I would prefer to keep it all running for as long as I can. What is my next step in the trouble shooting of this system and what repair options for the unit are still available as I am aware Raymarine bought Autohelm?

thanks for the help,

marty

[senormechanico]

Sounds like either a direct short or water leakage into the cable. What does it read with the transducer disconnected?

Steve B.

[martyk]

Steve,

Thanks for the reply, the same 2.2 is indicated when the transducer is unplugged. Some moisture was found in the instrument panel and I had similar thoughts concerning the potential of water running down the cables from the back of the unit to the plug on the pigtail. Since this plug is not potted or sealed to the cable coming from the unit my thoughts are to cut it off and install individual spade connectors on the conductors in its place that will go directly to the new ducer cable ends. Are there any downstream issues in this modification I should be aware of before I proceed?

thanks,
Marty

[Sunspot Baby]

The installation and operator manuals are available on line at the Raymarine web site. They might help in trouble shooting.

George

[senormechanico]

Marty,

As a retired electronics tech, I can not imagine any problems that would cause. Is there any moisture, salt buildup or corrosion evident in the plug socket on the head unit? What about condensation inside the display?

One thing you might try:
With the unit energized (both with and without the transducer hooked up), hold a portable AM radio (tuned off station at the bottom of the band and the volume turned rather high) against the display.
You should hear a fairly loud and regular tick tick tick about once per second in the radio along with the usual static. That will confirm the head unit is generating the pulse for the transducer.

Steve B.

Originally Posted by martyk

Steve,

Thanks for the reply, the same 2.2 is indicated when the transducer is unplugged. Some moisture was found in the instrument panel and I had similar thoughts concerning the potential of water running down the cables from the back of the unit to the plug on the pigtail. Since this plug is not potted or sealed to the cable coming from the unit my thoughts are to cut it off and install individual spade connectors on the conductors in its place that will go directly to the new ducer cable ends. Are there any downstream issues in this modification I should be aware of before I proceed?

thanks,
Marty

[martyk]

Steve,

Thanks again. No condensation noted in the display nor any salt residue on the wiring, only moisture on the cables and connectors. I'll try the AM radio test before removing the plug from the display pigtail for direct connection of the new transducer cable. When installing a new transducer is there a set up or calibration procedure that must be initiated before normal operation? I just want to be sure I am not high-centered on a set up issue.


Thanks,
Marty

[senormechanico]

As long as it's the correct transducer, it should be plug and play.
There is a setup for keel offset. It corrects for the depth of the transducer below the waterline or the depth below the keel, whichever you prefer.
You can program it with the buttons on the unit.
If you don't have the instruction manual that came with the unit, you can find it on the Raytheon website.

Steve B.

[martyk]

THANK STEVE,
I WILL GIVE IT A TRY TONIGHT AFTER WORK

MARTY

[martyk]

No Joy on the Auto helm ST-50!

The new transducer emits the audible clicking with the system on, and resetting the calibration parameters still does not yield an accurate depth reading. 200khz was the reported frequency of the transducer by the retailer though nothing in my manual confirms this. can anyone confirm the correct khz transducer for this unit, offer any alternate trouble shooting recommendations, or feedback regarding factory service?

thanks,
Marty

[senormechanico]

Marty,

Try this:

Raymarine Marine Electronics - Support Home

There are lots of questions and answers. If you don't find exactly what you're looking for, you can ask. A tech will answer you via email within a day or so.

Steve B.