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Adz seajay
26-03-2012, 09:15 PM
I think i need a little assistance with this one...

A while ago i installed a Lowrance HDS7 with LSS1 Structure Scan option as well and have been chasing a ignition related noise which presents as light and thin 45 degree bands across the screen on LSS1 structure scanning which runs one direction on the left scan, and the other direction on the right hand scan view, and also has some effect on normal sounding where by the screen clutters as though the sensitivity is cranked to the max.

The boat is a Aluminium center console with a 2004 suzuki 4 stroke.(electronic ignition)
And it only occurs when the engine is running and gets worse with increasing revs.

Now this is where its at, at the moment. I have gone through the entire boats power earthing points and motor grounding cables and made sure that everything is well grounded and also added a 12volt 10amp inline power noise suppressor directly behind the sounder unit from Jaycar electronics with good results, although the issue is slightly still apparent, but has improved quite a bit.

I can eliminate this issue totally by bypassing the house battery & running it of the trolling motor battery, but i would like to put this issue to bed as i sometimes don't bring the motor and battery to reduce weight at times and the sounder is still needed.

Any other suggestions would be more than appreciated.

74fpv01
26-03-2012, 11:23 PM
Check how close the transducer wiring is to any other cables. (especially , the battery cables ). Noise can be "transferred" if they are not shielded and are too close together. Good luck.


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cgibbo308
27-03-2012, 01:07 PM
The problem is the ign on the motor or at least thats causing the noise. you have done what i was thinking so thats good.
i was thinking you maybe able to use a small gell cell battery to run it, but you would have to make sure its fully charged and or can charge it while out.

You may, be able to contact suzuki and just ask them if they have any known noise issues
with their engines. they may know or may know of a way to get rid of the noise at the engine.

Having said that, it could even be a bad connection between the engine and earth if earthed to the boat. I would suggest checking all the plugs and wiring around the engine through to the battery.

all i can come up with so far :)

Jarrah Jack
27-03-2012, 03:34 PM
When you say everything is well grounded does that mean that your boat has a neg current and everything is grounded to it?

Flex
28-03-2012, 07:33 AM
How close do your sounder cables run alongside other cables in the boat? Try and separate them as much as possible. While DC current doesnt usually cause many induction issues you never know. Make sure your sounder cables are no where near your main batters power cables and especially your rectifier cables from your outboard they are most likely to cause this type of thing.

ThePinkPanther
28-03-2012, 09:20 AM
Best way is to take the power cables direct to the battery, like hot wire them!

If possible try to keep them away from the main electrical harness!

I have half a dozen sounders over the years and this has always resolved the "noise" problem.

Adz seajay
28-03-2012, 09:37 PM
Check how close the transducer wiring is to any other cables. (especially , the battery cables ). Noise can be "transferred" if they are not shielded and are too close together.

That was the 1st thing done during the install. Transducer cables on one side of the boat and power wire loom on the other.

Adz seajay
28-03-2012, 10:04 PM
The problem is the ign on the motor or at least thats causing the noise. you have done what i was thinking so thats good.
i was thinking you maybe able to use a small gell cell battery to run it, but you would have to make sure its fully charged and or can charge it while out.

You may, be able to contact suzuki and just ask them if they have any known noise issues
with their engines. they may know or may know of a way to get rid of the noise at the engine.

Having said that, it could even be a bad connection between the engine and earth if earthed to the boat. I would suggest checking all the plugs and wiring around the engine through to the battery.

all i can come up with so far :)

I have been meaning to contact suzuki direct regarding this issue.

And as far as the earthing issue there is continuity from all points from the engine block, leg, gear casing and mount and also measures great between all engine points and the Hull at the transom. Although the hull is negative grounded, all electric supply is supplied via a from a pair heavy guage battery cables and not through the hull. I have also tethered the alluminium on the center console directly to a welded rib in the hull. And all electrical connections within the motor from the charging system to the starter and ECU have all been cleaned, tightend and refitted.

I have also directly powered the unit to the house battery with its own dedicated wires and connections with no improvements... Sorry.

Also have installed new irridium resistor spark plugs allthough i have not replaced the coil leads off the plugs but as they are around $85 bucks each it gets a little pricey once the block is filled and the problem still isn't resolved.

The only other thing that i could think is maybe a injector resitance issue.

cgibbo308
28-03-2012, 10:59 PM
since you have check a few things. then all i could come up with that is left could be..
as you said a injector.
crook lead
crook coil
bit of corrosion on any number of wires
even the charge unit.

One extra thing we can try is:
i dont know your engine so you will have to fill in the blanks so to speak, BUT.
follow the harness (or a bunch of wires with bullet connectors) from your charging unit. there should be a plug on that line, probably close to the charging unit itself. unplug it. turn everything on then start it.
as you can guess if the prob is in or being caused by the charge unit, once unplugged it should stop the noise.

if this does stop the noise, give a local auto sparky a call or go see him and just ask what can be done. I know on the 4x4 my alternator has a condenser on the back of it to help stop this sort of thing happening,
next could be the rectifier breaking down.

Try the stator first then see what happens.
Chris

Jarrah Jack
29-03-2012, 08:13 AM
Its a seperate issue I think but the hull shouldn't be neg grounded as it promotes corrosion in the alloy.

Fed
29-03-2012, 09:15 AM
seajay, seeing that you can remove the interference by using the trolling motor battery then the problem is either dirty voltage at the main battery terminals or induced interference in the route the power supply to the fishfinder takes.
Which is it? It should be easy to find out by running a temporary supply from the main battery to the fishfinder well away from other cables.

To my way of thinking, earthing of the hull... one earth only through the motor bolts via the block and main negative from the battery.

Adz seajay
29-03-2012, 09:55 PM
Its a seperate issue I think but the hull shouldn't be neg grounded as it promotes corrosion in the alloy.

I've had this same discussion with my local Suzuki service fellow. And with my own trade background in electronics we butted heads one day when I put to him that any aluminum boat with a outboard strapped to it would be negatively grounded as any main part of the engine will always be -tve with reference to the polarity of the starter battery, unless the hull could be isolated somehow,(which is virtually impossible anyway) from the engine mount bracket and mounting bolts is unavoidable. But what we did come to is that as long as the voltage supply to all electrics is supplied via direct dedicated cabling from the battery and all the engine anodes are in good health, corrosion should be minimalised throughout the hull.

With the advent on modern day ignition systems and spark leads with inbuilt charge coils whereby with older dizzy ignition systems with a external coil, in some cases there was a condenser attached to the coil supply, which from memory was grounded to reduce noise, I now am thinking the possibly of applying a similar though with some small high temp non polarised filter capacitors to the stator leads and to ground in a attempt to quell the charge noise in question.

Does anyone know the value of a normal coil condenser capacitor?

Jarrah Jack
30-03-2012, 06:31 PM
Fair enough Adz. I found out my hull was neg grounded so I put an isolator switch on the neg as well as the pos. Wish I could help you with your more advanced question but its beyond me except to say its unusual.

Adz seajay
30-03-2012, 10:08 PM
Did a fair chunk of google research late last night and found a few a aerospace related forums with light aircraft owners resolving issues presenting exactly as mine, and following the same steps with regards to improving earthing and all electrical points and aftermarket inline voltage ripple filters as I also have, and turns out it might just be a poorly designed regulator rectifier unit with inadequate or non existent filter circuitry.
I won't go into the reason behind it as it involves a lot of electronics based pshyco babble, but if I was a betting man I would bet my left nut that this is the cause.
It might be a case of hooking up a good aftermaket regulator/rectifier unit.

Adz seajay
30-03-2012, 10:11 PM
I will keep you all posted as this issue continues.
Thanks to all for all your help.

cgibbo308
31-03-2012, 12:54 AM
You mean that a full wave rectifier could have shat and become a half wave? Lol
or it wasn’t made as a full wave in the first place?

do you have a cro you could test the output of the rectifier with?

Yet considering that its injected and hence computer controlled one would assume that its full wave, or at least made as a full..

The neg grounded hull..
I think I may have sent a pm to one of you about that yesterday or last night but can’t remember lol
the hull will be neg ground in respect to the battery. But as long as it’s not part of the cct There should not be a problem i dont think.


with regards to adding a non pol cap. i think all one would have to do is
measure the output (ac v) at the stator, and or on the output of the rectifier at wot. Then pick a cap that will not go bang, then just shove it across the output of the rectifier. If you want you could add a choke inline b4 the cap for good measure i guess. As for a regulator, your on your own with that. sleepy time now.:o

fullwave choke
78466

fullwave bridge choke
78467

fullwave bridge capacitor
78468

Flex
31-03-2012, 07:03 AM
WHen you mentioned the problem gets worse with increasing Revs, I'd bet your left nut aswell its the rectifier.

Outboard Rectifier's are fairly crude things I'd imagine. I never looked at them but do they come standard with a capacitor?

Fed
31-03-2012, 09:16 AM
If it was a Suzuki design problem it would be common knowledge by now.

I'm betting Flex's left nut that it's either a connection fault or a problem with the cable routing.

Cav(J.C.)
01-04-2012, 11:32 AM
Might be a stupid question, but does this problem occur when the engine is revved out of gear?
Cav(J.C.)

Adz seajay
02-04-2012, 10:46 PM
Yep.

Next is to fit a high temp polarised cap to absorb some of the AC ripple voltage across the output of the rectifier and or to fit a shunt diode to fully block any further AC ripple voltage.

cgibbo308
03-04-2012, 12:15 PM
:2thumbsup:

keep us informed eh :)