Depth Sounder Troubleshooting

[exposure]

On my new boat the depthsounder was acting up during the sea trial. The display was erratic and not making sense at times. All of the other instruments were just fine.

Now I am quite handy with things electrical and otherwise. But I am not very familiar with depthsounder issues. The boat is on the hard now and I plan to put it in the water in May. I plan to try and fix this before it goes in the water. Is there a way to test the unit, including the transducer, while it is on the hard?

If I check the wiring and find something to fix, then put the boat in the water and find it still is not functioning properly, I will have to pay to haul the boat again and swap out the system, including the transducer.

The sounder is part of a complete set of older VDO units that have repeaters at the nav station. I would like to get the unit to work both for financial reasons and to keep the set in tact. But, If I know I could not fix the unit I would rather just install a new setup prior to putting the boat in the water.

Any ideas?

Thanks, Woody

[GordMay]

There is no easy way to test a transducer. I have not found a way, even with a shop full of test equipment. You need a scope, an oscillator (and/or a Bal-un) and the knowledge to use such test equipment. A basic meter simply doesn't do it.

If the Sounder works with another transducer (hung over the side), then you know it’s a transducer (or cable) problem - and you replace the transducer & cable (as a set). Whether the problem is a broken cable or faulty transducer, you still have to
change it.

Since Airmar supplies about 90% of all transducers used by all the depth sounder companies, chances are good you can find such a version - # http://www.airmar.com/ (Gem Electronics is their US distributor and handles spare parts, accessories and aftermarket sales. They can be reached by phone or fax at the following. Phone: 843-394-3565 - Fax: 843-394-3736)

It’s not really practical to splice a transducer cable, since such splices alter the capacitance &. impedance of the transducer cable. That in turn requires making circuit tuning changes inside the head. And that is definitely a highly skilled bench job.

Take a look at some of the test equipment used to troubleshoot Depth Sounders:
http://www.dsts.com/

[delmarrey]

What I've done in the past is pull the whole unit, transducer and all. Then ship it to the manufacture and let them test the system. I ended up buying a whole new system because it cost more in repairs and trouble than what a new one was worth. Contact the manufacture first to see if they can test the unit and go from there. Also the newer units have more options like water temp. and SOG but a little more $$ as well. If a new unit is in order, be sure to check the transducer size or shape to fit the old thruhull if it's a concern. Some are flush with the hull.

One more thing! if you do pull the transducer, check that the core of the hull is sealed. That is a very common place where water enters the core.

[exposure]

I guess what I am trying to do is to find a way to test the depth system prior to putting the boat in the water. The only way I can think of is to pull the transducer out and stick it in a gargage can full of water.

I am hoping that the problem is wiring and I can fix the system. But, the price of a new sounder is not much more than the price of a haul out and I don't want to put the boat in the water then find it doesn't work and have to pay for a haul out AND a new sounder.

Also, the hull is not cored so water intrusion into the core should not be an issue. Do you mean water intrusion into the glass layers that could lead to blistering?

Woody

[BC Mike]

Gord has given you the answer here. The boat is in the water and you may know the depth. Hang the transducer over the side and see if it works. If it does not then try another transducer, if it still does not work send the unit to the fixit shop. If the hull is solid fibreglass you can shoot through it. Smear some silicone type stuff on the inside of the hull and set the transducer in it, turn it on and try it, if it does not work move the transducer until you find a spot that works. This is after you have the unit working. I have my transducer about 18 inches behind the back of the keel, used a cheap sealer and it has been there for over 20 years. BC Mike C

[delmarrey]

The core statement was just an assumption. Most boats usually have some kind of core, either foam or wood. I can't remember what boat you have.

If the unit is not too old, you could just replace the transducer for the $200 or so. And if it still doesn't work then you know it's the display.

Also, the manufacturer may be able to give you an Ohm resistance value for the transducer.

Del

One more thing do not use silicone use a 3M-5200, 4200 or even a 101 for thruhull fittings but not silicon. I can show you pictures of some thruhulls where the stuff came out all in one piece like a gasket. Silicone does not stick to fiberglass or wood underwater. That's why marine sealers are more expensive, they work.

[exposure]

From the discussion above it looks like the best option I have is to try and fix the wiring. If it looks like it might be working, I'll pull the transducer from the hull and drop it down into a garbage can full of water to test it. If that works, I'll reinstall the transducer (including rebedding it) and have the boat put in the water. Hopefully it will work at that point. If it gives me problems after it is in the water I'll buy a new depth unit with a transducer and try installing it shooting through the fiberglass hull, at least until the next time I haul the boat.

The unit is a VDO brand from around 1990, I don't think I could find another transducer to try a swap.

I really need a working unit as soon a the boat goes in the water the end of May. We will be heading down the ICW to Florida ASAP. Of course there is always a lead line if all of this fails.

Thanks,
Woody

[GordMay]

Transducers have a limited lifetime (Factory informed me 5 - 10 years, tho' I got 15 yrs).
I paid < $150 for a new Transducer in 1999.

VDO Depth Sounder Manual (See pages 13 & 14 for Troubleshooting):
http://www2.vdo.com/vdo/sycomax/file..._OLdepth_e.pdf

and
Transducer Instructions (English starts on page 4)
http://www2.vdo.com/vdo/sycomax/file..._Schwinger.pdf

and
Instrument Repair Locations:
http://www.vdona.com/Tech%20Support/repairpage.htm

In The United States Contact VDO @
Siemens VDO Automotive Corp.
North American/Trading & Aftermarket
Address:
Westfield Corporate Center
4905 Tilghman Street, Suite 120
Allentown, PA 18104
Tel: (610) 289 0488
Fax: (610) 289 1399
http://www.vdona.com
Email: rutter@siemens.com

[exposure]

Thanks for the links. Unfortunately my unit predates the model shown. The transducer looks quite different as well. I suppose it could be the age of the unit that is causing the problem. I wonder if it matters how much it was used. Mine was used very little.

Thanks, Woody

[AnchorageGuy]

exposure, The things that probably are causing the problem are these. The transducer is bad. Send it back for service now since the boat is out of the water. If it is OK you only paid shipping. Send both the head and transducer. No trash can is going to tell you this. Next, too much voltage to the 12 volt supply. Usually from the alternator not working properly. Does the problem only occur when the engine is running. And last, RF getting into the cable. Move all the wiring to eliminate the RF interference. Good luck.