Nasa Target Echo electrical interference

[greggron]

My Nasa Target echo sounder goes berserk when my engine (9.9AE Yamaha inc. alternator) is on, otherwise depth readings are fine. The transducer is fitted as far away from the engine as it can be on a 22 footer and has not been cut. I realise that the oil around the tranducer head might need topping up/changing as the effect might be caused by vibration.

How do I do that (does it just pull out - I have no manual)?
What oil should I be using?

If that doesn't work, I have heard that you can fix a capacitor between the connections on the back of the display unit which will cut out electrical interference.

What specification should I use?
How do I do it?

Possibly naive questions I know but any help appreciated.

Greg

 

[crossbones]

Targer sounder.

You can get the instructions here:-

http://www.nasamarine.com/pdfs/Target 2 Log, Depth + Wind.pdf

Use ordinary vegetable cooking oil in the transducer mount. It's best to clean the old stuff out first. A good transducer mounting will ensure the best possible echo. If you still get interference (which isn't caused by turbulance under the transducer) then you need to suppress it as close to the source as possible. This usually means a capacitor across the terminals of the alternator.

 

[VicS]

I'd expect the transducer to simply pull out. My seafarer one does. It is fitted through the cap on the mounting tube and the cap lifts off complete with transducer. I suggest though you don't put it by the transducer stem. Ease the cap off. I'd be surprised if it is screwed on but worth bearing mind that it might be.

The oil. Seafarer recommended castor oil. Nasa don't say what the oil is that they supply. You, need to top up with the same...perhaps Nasa will tell you what oil you should use, otherwise I think I'd clean out all the old oil and put in fresh.

BUT if there is no sign of the oil leaking it is probably still OK

The interference. Funny this my Seafarer runs happily on the ships supply even when the engine (Evinrude outboard) is running. My friend could not use an identical Seafarer on the ships supply with his diesel engine running! He had to use an internal battery! Illogical!

Curing the interference may be a big trial and error exercise with capacitors and or ferrite beads on the supply wires.

 

[greggron]

Thanks for the advice. It's not a sounder oil thing, I have checked that.

So it seems that I shall have to play around with capacitors etc. What is a real shame is that Yamaha themselves seem to offer little/no advice on this anywhere I can find.

1. Does anyone have any info?
   
2. What capacitor I would need?
   
3. Where/how would I fit it?

I am reasonably competent but outboard electrics are a mystery to me.

 

[Alex_Blackwood]

My Nasa Target echo sounder goes berserk when my engine (9.9AE Yamaha inc. alternator) is on, otherwise depth readings are fine. The transducer is fitted as far away from the engine as it can be on a 22 footer and has not been cut. I realise that the oil around the tranducer head might need topping up/changing as the effect might be caused by vibration.

How do I do that (does it just pull out - I have no manual)?
What oil should I be using?

If that doesn't work, I have heard that you can fix a capacitor between the connections on the back of the display unit which will cut out electrical interference.

What specification should I use?
How do I do it?

Possibly naive questions I know but any help appreciated.

Greg

First of all Check your cable runs. If the cable from the transducer is running alonside other cables try seperating them if you can get a couple of inches so much the better. If the cables are crossing try and cross at right angles. Worth trying before fiddleing with capacitors etc.

 

[cimo]

My Nasa Target echo sounder goes berserk when my engine (9.9AE Yamaha inc. alternator) is on, otherwise depth readings are fine. The transducer is fitted as far away from the engine as it can be on a 22 footer and has not been cut.

Greg

hello greg. what do you mean by berserk?
does the display act up to the point you can't read it
or is it the readings jumping all over the place
or just incorrect steady readings?
rgds
c

 

[AngusMcDoon]

My Nasa Target echo sounder goes berserk when my engine (9.9AE Yamaha inc. alternator) is on, otherwise depth readings are fine.

Unortunately they have a reputation for doing that. When I had a Nasa/outboard combination it did exactly the same. There was no fix that I could find. Others have reported the same problem.

The easiest solution is replacement with better quality kit.

 

[jjulysses]

Looks like a Radio Frequencies Interference problem.

General:
- Rout all wiring as far away from noise sources (alternators, fluorescent lights, electrical motors, TV, and video screens).
- The boat should be properly bonded (i.e. metal objects, shielding of wiring, electrical equipment connected to the common ground of the boat.
- The electrical wiring of the instrument should be shielded, the shield connected to the common (electrical) ground of the boat in several places.
- Bond in the rigging and chain plates, tighten rigging screws properly, bypass rigging screws and shackles electrically; do the same to guard wires.

RFI should be eliminated at the source and not the instrument giving erroneous results!

- Supposing you have a diesel engine:
On the alternator:
Fit a separate ground strap from the alternator to the engine block, or better to the boats common ground.
Connect a 1 µF capacitor between the output terminal of the alternator and the ground.
Connect a 1 µF capacitor from the voltage regulator‘s batterie connection to the ground.

On all electrical motors:
Connect the input and output leads with a 1 µF capacitor as close to the motor as possible.
Connect the brush leads with 1 µF capacitors to the ground.
Clean brushes and commutator.

On a gasoline engine, additional work has to be done: exchanging spark-plugs, capacitor on ignition coil if present, HT cables, wiring of tachometer. Ask an automobile mechanic familiar with proper radio installation.

All capacitor connections should be as short as possible (clip long stubs).

<ulysses>

 

[cimo]

Looks like a Radio Frequencies Interference problem.

General:
- Rout all wiring as far away from noise sources (alternators, fluorescent lights, electrical motors, TV, and video screens).
- The boat should be properly bonded (i.e. metal objects, shielding of wiring, electrical equipment connected to the common ground of the boat.
- The electrical wiring of the instrument should be shielded, the shield connected to the common (electrical) ground of the boat in several places.
- Bond in the rigging and chain plates, tighten rigging screws properly, bypass rigging screws and shackles electrically; do the same to guard wires.

RFI should be eliminated at the source and not the instrument giving erroneous results!

- Supposing you have a diesel engine:
On the alternator:
Fit a separate ground strap from the alternator to the engine block, or better to the boats common ground.
Connect a 1 µF capacitor between the output terminal of the alternator and the ground.
Connect a 1 µF capacitor from the voltage regulator‘s batterie connection to the ground.

On all electrical motors:
Connect the input and output leads with a 1 µF capacitor as close to the motor as possible.
Connect the brush leads with 1 µF capacitors to the ground.
Clean brushes and commutator.

On a gasoline engine, additional work has to be done: exchanging spark-plugs, capacitor on ignition coil if present, HT cables, wiring of tachometer. Ask an automobile mechanic familiar with proper radio installation.

All capacitor connections should be as short as possible (clip long stubs).

<ulysses>

You're setting the OP up for a busy time jjulysses. 1uf caps? - very specific. what RF range are are you assigning as root cause? are you so sure 5uF would not be better? Multi-point shield connections - ground loops to be avoided I would have thought? If this is an alternator whine issue (could be), perhaps cleaning the electrical connections starting at the battery terminals would be a good start?
rgds
c

 

[Seanblower]

Seanblower

Years ago I had a NASA Target sounder which was unreliable and gave false readings. I swapped it for a NASA Clipper using the same transducer. Problem solved ! I have since installed the Clipper on two other boats with no problems ever.

 

[BruceDanforth]

It may not be RF from the engine as suspected. I have one of these units doing the same and thought the cause was the outboard but the boat needs to be underway under engine. If I run the engine full throttle with the boat tied in her moorings I get no interference. Underway then the display goes crazy. Sailing at the same sort of speed it works fine.

 

[dmayes]

Capacitors

Go to an older car spares shop. Some time ago you could buy suppressor capacitors to install on car engines/electrics. Your outboard charger will be AC and then go through a diode bridge to become ripple DC. Make sure that you don't put the capacitor on the AC side or it wall act as a short circuit, they are supposed to suppress/short out radio interference superimposed on the DC.

 

[pampas]

Also the Target range does not have the averaging function fitted as opposed to the Cruiser and above Mk`s, therefore jumping displays you will have to live with. suppression and ferrite beads will help.

 

[VicS]

It might be worth trying the ES on an independent power supply. Another small 12 volt battery or a couple of lantern batteries in series perhaps.

If it works Ok on that it is worth pursuing the idea of adding capacitors etc to the normal supply, trying both suppressing at the engine output and at the ES power input.

Also look at the way things are wired, a "clean" supply direct from the battery may help if the charging wiring from the engine and the power supply to the ES are common at any point .

 

[machurley22]

I had the same problem with the same Nasa unit and an old Yamaha 8CM with a charging coil rather than an alternator. My particular set-up gave reliable readings at tickover (and so you could always knock the engine back for a few seconds when required) but random readings otherwise. A couple of ferrites on the lead from o/b to battery helped and a couple more cured the problem.

Obviously there's no guarantee that this will also work for you but as the easiest and cheapest potential fix it's definitely worth a try first IMO.

 

[greggron]

Thanks for all the input. Lots to think about!!

I also spoke to a pretty helpful guy at Nasa Marine and he recommended I pop down my local auto shop for an alternator suppressor for a few quid. So I did and he's waiting to get some in. I'll try that first.

The thing was working fine until the beginning of last season with the wiring in the current tracks. I haven't changed anything of the layout at all so I'll start with the suppressor and work my way through the options.

Greg

 

[cimo]

hello greg
if it was working fine before and you haven't changed anything - something changed of its own accord.

Perhaps you have some loose or corroded electrical connections.
Check & clean the alternator and battery connections. Provided they are clean and well made, the battery will in effect act as a low impedance load (or short circuit) for conducted noise - the connections must be low impedance though - hense the cleaning.

An alternator faulty diode will produce noise also - any near misses with your alternator lately?

try the supressor by all means - but you are not getting to the root of the problem by the sounds of it.

If its radiated noise, you can try separating power cables from your signal cables as already suggested.

Could assist some if you were to describe what the display is doing when it goes "beserk"?

happy hunting

 

[VicS]

The thing was working fine until the beginning of last season with the wiring in the current tracks. I haven't changed anything of the layout at all so I'll start with the suppressor and work my way through the options.

Start by cleaning all connections. From the coils in the engine (I guess we are taking charging coil under the flywheel) the rectifier all the connections between engine and battery. Then all the connections from battery to sounder.

Dont forget that incldes the negatives as well as the positives.

No chance I suppose that you have run the sounder direct from the engine without the battery connected. The output from the engine may not be regulated so could have put a big voltage into the sounder and may have blown something in there (I did it with my Autohelm )

 

[BruceDanforth]

What did you do to the autohelm? I just repaired mine by replacing the output transistors. The motor in mine is driven in such a way that a back emf is always going to act to shorten the life of the output stage and I can't see a way to protect as the current goes both ways. The symptoms for this are that it beeps just doesn't move.

 

[VicS]

I sent if off for repair ... it may have been for an unconnected problem ... but they found that the voltage stabilising circuit had burnt out ... it was such an unusual fault that they actually managed to get a message to me at work to contact them.

As soon as they told me I knew what I had done. I'd forgotten to connect the battery and as a result it had run off the unregulated output from the outboard.

Long time ago, late 1980s when Autohelm was still Autohelm and the service was second to none.