I read up on this test. Would be very interested to know the results. Neither my electrician nor mechanic have the tool. What should I expect to spend on one that would do the job? I see cheap ones on Amazon but figure this is probably not the ones I want.
Dff3d Interference From Alternator - *UPDATE #4* Filter Capacitor Fixed It!
- Thread starter ToddF
- Start date
How important is keeping the foil on the individual wires for the 1.5" it looks like in the pic? Mine are trimmed back to the black wire sheathing, in other words, no foil stands out beyond the black cable insulation. Other than that, I think I did it as pictured.
jp498
Furuno Super Fan
For these purposes a cheap ipod style o-scope would be fine. More money gets higher frequencies, more channels, etc...
It's been a while but figured I'd update this thread.
Did a lot of reading up on marine grounds, analysis, and eventually rework on critical parts of my ground, supply, charging and bonding systems. This meant shortening unnecessarily complicated wiring paths, separating the bonding system from the DC negative side (except in 1 spot) , replacing corroded or overused busses, upping wire sizes, lots of new terminals, and double checking my NMEA 2k wiring and drain wires according to Furuno S-1 schematics. Worthwhile work but it didn't fix my dff3d issue.
I've isolated the problem to the engine alternator. I replaced the old alternator with a brand new one, since the other was old and the windings were looking a little rough, and yet the problem remains even with the new unit. I then upgraded the size of the alternator output wiring and added an equal sized ground wire (to main DC neg bus) running together (via cable ties) for as much of the run as possible.
Here's why I'm convinced it's the alternator:
-With DFF3d in Triple beam and Cross Section and depth set very deep, I'm getting the searchlight cone (Cross Section) and hash (Triple Beam) in direct proportion to the RPM on the Yanmar. This happens in neutral as well as in gear so I think I can rule out the spinning shaft.
-When I disconnect the excitation wire form the back of the alternator, the interference goes away! Hooray!
-If I add an 8 AWG wire from the black box (instead of 12 AWG I have) and run it to the engine block or to the common ground bus (running gear, thru hulls, zincs etc) then the problem remains as long as that alternator is producing current. Booo!
So now I can either:
A) Put the excitation wire on a switch where I can deactivate the alternator when using the Dff3d or preferably
B) Add some sort of filtration to the alternator output. I read on here about Filter Capacitors being used for similar motors and other black box sounders. Also, I've also seen a similar product Newmar sells called an Alternator Noise Filter 150A. The Newmar wires up in line to the output, while the Filter Cap seems to wire parallel to the output wire so I'm guessing they work differently
Curious if anybody has any experience with filter capacitors or the Newmar Alternator noise filter. As always, if I'm missing something or on the wrong path please advise.
Did a lot of reading up on marine grounds, analysis, and eventually rework on critical parts of my ground, supply, charging and bonding systems. This meant shortening unnecessarily complicated wiring paths, separating the bonding system from the DC negative side (except in 1 spot) , replacing corroded or overused busses, upping wire sizes, lots of new terminals, and double checking my NMEA 2k wiring and drain wires according to Furuno S-1 schematics. Worthwhile work but it didn't fix my dff3d issue.
I've isolated the problem to the engine alternator. I replaced the old alternator with a brand new one, since the other was old and the windings were looking a little rough, and yet the problem remains even with the new unit. I then upgraded the size of the alternator output wiring and added an equal sized ground wire (to main DC neg bus) running together (via cable ties) for as much of the run as possible.
Here's why I'm convinced it's the alternator:
-With DFF3d in Triple beam and Cross Section and depth set very deep, I'm getting the searchlight cone (Cross Section) and hash (Triple Beam) in direct proportion to the RPM on the Yanmar. This happens in neutral as well as in gear so I think I can rule out the spinning shaft.
-When I disconnect the excitation wire form the back of the alternator, the interference goes away! Hooray!
-If I add an 8 AWG wire from the black box (instead of 12 AWG I have) and run it to the engine block or to the common ground bus (running gear, thru hulls, zincs etc) then the problem remains as long as that alternator is producing current. Booo!
So now I can either:
A) Put the excitation wire on a switch where I can deactivate the alternator when using the Dff3d or preferably
B) Add some sort of filtration to the alternator output. I read on here about Filter Capacitors being used for similar motors and other black box sounders. Also, I've also seen a similar product Newmar sells called an Alternator Noise Filter 150A. The Newmar wires up in line to the output, while the Filter Cap seems to wire parallel to the output wire so I'm guessing they work differently
Curious if anybody has any experience with filter capacitors or the Newmar Alternator noise filter. As always, if I'm missing something or on the wrong path please advise.
Last edited:
jp498
Furuno Super Fan
Next step might be to get some ferrite chokes such as https://www.ebay.com/itm/356643154708
or https://www.ebay.com/itm/196336379408
Zip ties these around wires from the alternator, wires going into the dff3d, LED lights, go crazy with them.
Before you touch a thing, listen to how many VHF weather channels you can get, then do the work and check again.
or https://www.ebay.com/itm/196336379408
Zip ties these around wires from the alternator, wires going into the dff3d, LED lights, go crazy with them.
Before you touch a thing, listen to how many VHF weather channels you can get, then do the work and check again.
I added a capacitor to my alternator (pos to alternator output post with charge wire, neg to engine block) and it appears to have fixed the problem! No signs of the dreaded torchlight at the dock! This was at all RPM's and the dff3d range at 600-800ft in cross section view. I was able to double the amount of gain I can use with the dff3d and even by b175HW seems like a cleaner image. This took me 10 months but I think we finally got it.
This was a thread I found on here that introduced the idea of a capacitor:
https://furunousaforum.com/threads/295-with-r99-engine-interference-and-troubleshooting-steps.6469/
This is what worked:
Mallory CG153U050W4C 15000 MFD 50vdc 85° CG Series Capacitor
And this is where I got it:
www.ebay.com
Thanks to all. Hopefully things stay clutter free.
This was a thread I found on here that introduced the idea of a capacitor:
https://furunousaforum.com/threads/295-with-r99-engine-interference-and-troubleshooting-steps.6469/
This is what worked:
Mallory CG153U050W4C 15000 MFD 50vdc 85° CG Series Capacitor
And this is where I got it:
Mallory CG153U050W4C 15000 MFD 50vdc 85° CG Series Capacitor for sale online | eBay
Find many great new & used options and get the best deals for Mallory CG153U050W4C 15000 MFD 50vdc 85° CG Series Capacitor at the best online prices at eBay! Free shipping for many products!
Thanks to all. Hopefully things stay clutter free.
Great job and thanks for sharing your solution to cleaning the boat noise. Well done!
