Nelson 42 - Electrical problem advice and help needed.

[Trigg732]

Hi to you all and hope you are keeping safe and sound.

I currently own a Nelson 42, 1992 and am having a few problems with the electrics. I have not owned it long and I am just wading my way through the mix of factory and DIY wiring that seems to exist on her, well what do you expect for an old lovely boat.

So here is the problem......

The previous owner fitted a new 'Standard Horizon' VHF unit and when I picked her up it all worked fine, in that it would power on. The all of a sudden it has stopped working.....strange..... The unit is wired so it can be removed so I did some testing. I found that without the unit connected there was 13.7V at the connector. When I connected the unit that dropped to about 4.1V so somewhere on the circuit there is a resistance, so here is what I have done so far. -

1. The unit is wired so its removable from the boat, so I took it to be tested and serviced, it powers up on the bench drawing about 13.7V at 0.3amps
2. I replaced the DIY wiring directly by the unit, checked and replaced the inline fuses
3. I traced the wiring back to the switch on the panel by the helm and it all looks good but old
4. I took the switch panel off and tested at the switch, same thing 13.7V when not connected 4.1V when connected.
5. I replaced the switch thinking that may be causing the resistance but again the unit did not power on and dropped to 4.1V when tested.
6. I then traced the wiring from the switch back to a 'Bakelite' junction box, I have not managed to get to it to check inside as its really awkward to get to

I then noticed the shore line power cable had been split as the marina fuse kept tripping when I tried to plug her in. I then noticed that both socket ends were full of water so I have replaced the shore power lead and all is good. Ever hopeful I thought that may have solved the problem, but after about 3 hrs of charge same issue.

7. As far as I can tell the electronics and VHF radio run off of the battery bank under the helming position, I found this out by switching between the isolator switches and I have power to the VHF radio when the isolator on the engine battery bank is ON and the leisure side is OFF.

I was told the batteries were new 'ish', but looking at the terminals there is some greening on the outside of the battery pillars. I don't think its the batteries as all the other nav electrics work fine.

So I am a little stuck as to where to look and test next, I know its going to be something simple and I have missed it but I seem to be looking in the wrong place. So if any of you wiser and far more clervvvere people than me have any suggestions at all it would be greatly appreciated.

Kindest regards

Paul

 

[Trigg732]

Hi and hope you are all well and safe.....

I am having a few problems trying to fault find an electrical problem on my Nelson 42, she is basically made up of factory and DIY wiring so a bit of a mismatch, but the what do you expect from such a lovely old boat. So here is the problem --

The previous owner fitted a 'Standard Horizon' VHF radio, it was hard wired but also you are able to remove it when not on the boat. When I picked the boat up it all worked fine, then all of a sudden it has stopped working, in that it won't power on. Because it seemed like a DIY installation there were plenty of points I could test. When the unit is not connected I am getting 13.7V at the connectors, but when it is connected I am only getting 4.1V and it won't power up. So obviously there is some resistance in the circuit somewhere, so here is what I have done so far -

1. I have had the unit tested and serviced, it powers up on the bench pulling 13.7V and 0.3amps, so the unit is fine
2. I have sorted the wiring leading to the unit, re tested it and the same problem.
3. I have taken it all the way back to the switch on the helm panel, cleaned the connection points same problem.
4. I have replaced the switch tested it again and the same problem continues.
5. The wiring from the switch goes to a 'Bakelite' junction box which is awkward to get to, so I have not managed to test it there as of yet.

The next thing I found was the shore lead was split, both ends of the lead were water logged and the boat would not charge, so I have changed that and tested it and its all works fine. thinking this may have solved the problem after 3 hours of charging the VHF radio still had the same fault and would not power on.

I was told the batteries were new when I got her, but the battery pillars are a little green, however all of the nav electronics work from the same battery bank and they all power up fine. So I am a little stuck as to where to look next, I know its going to bed something really simple but any advice of where to look next would be greatly appreciated.

kindest ragrds

Paul

 

[jrudge]

Is it a 12 or 24 volt boat ?

if a 24 volt boat the 12v supply is provided by droppers. The droppers do play up when older and can produce similar issues.

if a 12v boat I would imagine you have a corroded earth. Run a bit is wire to the battery negative and the unit negative to proove it. I have a similar issue with my saloon tv what runs of a dropper ( it is not the dropper ) so need to resolve next time I can get to Mallorca.

 

[spannerman]

I have seen this type of fault many times on boats, the supply can show the correct battery voltage to a multimeter which doesn’t draw any current, but when a consumer is connected it falls. This is a bad connection between the battery and consumer which can’t pass the current draw required by the consumer. Easy way is to run a wire direct from battery positive to the VHF to see if it works correctly, if so work through the system or just rewire that circuit if its old.

 

[volvopaul]

Hi to you all and hope you are keeping safe and sound.

I currently own a Nelson 42, 1992 and am having a few problems with the electrics. I have not owned it long and I am just wading my way through the mix of factory and DIY wiring that seems to exist on her, well what do you expect for an old lovely boat.

So here is the problem......

The previous owner fitted a new 'Standard Horizon' VHF unit and when I picked her up it all worked fine, in that it would power on. The all of a sudden it has stopped working.....strange..... The unit is wired so it can be removed so I did some testing. I found that without the unit connected there was 13.7V at the connector. When I connected the unit that dropped to about 4.1V so somewhere on the circuit there is a resistance, so here is what I have done so far. -

1. The unit is wired so its removable from the boat, so I took it to be tested and serviced, it powers up on the bench drawing about 13.7V at 0.3amps
2. I replaced the DIY wiring directly by the unit, checked and replaced the inline fuses
3. I traced the wiring back to the switch on the panel by the helm and it all looks good but old
4. I took the switch panel off and tested at the switch, same thing 13.7V when not connected 4.1V when connected.
5. I replaced the switch thinking that may be causing the resistance but again the unit did not power on and dropped to 4.1V when tested.
6. I then traced the wiring from the switch back to a 'Bakelite' junction box, I have not managed to get to it to check inside as its really awkward to get to

I then noticed the shore line power cable had been split as the marina fuse kept tripping when I tried to plug her in. I then noticed that both socket ends were full of water so I have replaced the shore power lead and all is good. Ever hopeful I thought that may have solved the problem, but after about 3 hrs of charge same issue.

7. As far as I can tell the electronics and VHF radio run off of the battery bank under the helming position, I found this out by switching between the isolator switches and I have power to the VHF radio when the isolator on the engine battery bank is ON and the leisure side is OFF.

I was told the batteries were new 'ish', but looking at the terminals there is some greening on the outside of the battery pillars. I don't think its the batteries as all the other nav electrics work fine.

So I am a little stuck as to where to look and test next, I know its going to be something simple and I have missed it but I seem to be looking in the wrong place. So if any of you wiser and far more clervvvere people than me have any suggestions at all it would be greatly appreciated.

Kindest regards

Paul

I was always told to wife a vhf direct to a battery so in the event of a fire or high water ingress the supply would maintained should you need to turn off the main breakers , the fault of voltage drop is obviously in the supply so I’d be re wiring from source to radio via a fuse you can get to easily , the same set up should be for bilge pumps too.

I guess your boat will be old so will the wiring , I’d have it checked over .

 

[oldgit]

I was always told to wife a vhf direct to a battery so in the event of a fire or high water ingress the supply would maintained should you need to turn off the main breakers , the fault of voltage drop is obviously in the supply so I’d be re wiring from source to radio via a fuse you can get to easily , the same set up should be for bilge pumps too.

I guess your boat will be old so will the wiring , I’d have it checked over .

+1
quickest simplest and probably cheapest !


Over the years stuff gets added to circuits via chocolate blocks , Scotch locks, butt connectors etc etc
Salt and moisture cause corrosion, resistance increases.It could have umpteen connections twixt radio and battery.
Good hint, radio will will work on receive but die on Tx.
If you have the time find ALL the in line fuses and all the connections and check for good clean connections.
Sometimes opening plastic fuse holders or pulling out fuses in blade fuse holders reveals a green corroding powdery mess.
In some extreme cases the blades on alloy fuses can vanish completely.
Another tip, to do it properly ,spray stuff with proper switch cleaner not WD40.
Radio will need 10Amps...so some nice thick cable please, be nice if you used red and black for the sanity of any future owner.
We frequently used to get "faulty" marine radios in our workshop at least half went back with NFF. Its the wiring mate !
The other frequent problem was owners reversing the polarity.
On older radios simple cheap fix, change the diode. On new stuff it was frequently good bye radio as BER.

 

[Trigg732]

All thank you all so very much for your tips and advice, some really good things for me to try next time I am at the boat. You are all spot on with the green connectors, I have found lots on so many of the add on circuits with connectors that are not marine proof.

The boat runs off 24v, so droppers are on her, I have made up a long piece of cable that I can start to bypass various parts of the circuit to see where the fast exists, worst comes to the worst I will re-wire the circuit from a good 12v circuit that I know that works because I recently added a dropper to re wire the old wheel house lighting that was all corroded.

Thank you all again, I will update this thread when I find the problem and the solution so it may help others with a similar problem.

Thanks again and stay safe.