Here's the story...I bought a Standard Horizon GX1300E VHF radio from Whitworths. I installed it in the same place as
the original radio because of the antenna setup. After installation I switched it on and it didn't work. I pulled the connections
apart and pushed them back together and it was completley dead. OK I'd bought a dud. I demounted it and took it back to
Whitworths, they looked surprised and got a small battery put the wires on the terminals and it fired up. What the....
I took it back to the boat, hooked it up, it didn't work.
The power lead comes out of the back of the radio and at about 100 mm there's a plastic connector which attaches to
an extension lead of about 600 mm that contains the fuse, this then is connected to the power line from the control panel.
My multimeter told me I was getting 13.8 v at the plastic connector, but the radio wouldn't work. So I disconnected it
from the lead from the control box and, took it over to my house battery put the leads onto the the terminals and it fired up.
Reinstalled it in it's proper position and it didn't work although I was still getting 13.8 v at the plastic connector. So what is
going on ?. It is not logical for it to work only on the Stbd side of the boat and not the Port side. The battery voltage was
13.8 the same as the plastic connector. What difference does it make hooking it up to a battery at 13.8 v to hooking it
up to it's plastic connector 100mm from the radio at 13.8 v. I'm completely stumped.

the connectors themselves are a common source of poor connections...

Ah...good response. Thinking now maybe I should run a lead straight from the battery to the radios position. If
the radio fires up then it must be lack of current....which i must admit I hadn't given any thought to. If there is a
breakdown in connection it's more than likely between the control panel and the new power lead. Actually..now
I come to think of it, there' s a fuse still in the original power lead from the control panel, I bet that's where a bit
of corrosion has taken place.
Thanks a lot fellas....good work.

fishmonkey said..
you could also troubleshoot by testing the resistance of the wiring (disconnected from the battery of course)...

OK Fishy. How do I use the multimeter to do that ?.

samsturdy said..

fishmonkey said..
you could also troubleshoot by testing the resistance of the wiring (disconnected from the battery of course)...

OK Fishy. How do I use the multimeter to do that ?.

set your multimeter to one of the resistance (measured in Ohms) settings. when you touch the probes together, the resistance should be close to zero. each of your wire runs should also be close to zero (from end to end). test the positive and negative wires separately...

'tis the season for this sort of stuff.

I've had not one, but two devices on my boat not power up this week because each's inline fuse holder had developed corrosion that made the circuit high resistance. The corrosion was so minor, that a casual glance would miss it. If it isn't the fuse holder it will be sure to be another connection in the circuit.

Testing with a multimeter may work. The risk is that on ohms range the voltage is very low (ie 0.2V usually) and test current very low too (0.001A). You might not see a faulty corroded joint .

Silly though it sounds, in this case something like a 10W light bulb would be better to check if the 12V is there and no high resistance joints {like what Charriot said) . ie. A brake light bulb from car or similar.

Trek said..
Hi Sam, how did you go?

Hi Trek, Haven't been to the boat yet, too hot yesterday and other things are getting in the way (as usual ) but
I'm confident that you've all got it right in saying it's a bit of corrosion somewhere. I will report when I've done
the deed.

Thanks all.

samsturdy said..
Finally, I got to the boat. Re-tried the radio again to no avail so I cut the wires back past the existing fuse and
tried again, no good. It didn't matter how much I cut the wires back it was never going to work so I rewired the
the whole thing and 'Bingo' we have a working radio. So now I'm thinking perhaps the original wiring was not
tinned and had corroded right through. Anyway the upshot is that you were all right about corrosion being the
cause...and he's now fixed.

Hallelujah,, oh joy oh joy , now whats next? You do know there will be a next don't you....

samsturdy said..
If you suspect that corrosion is occurring at the back of your control panel, is there something you can
spray on it to get rid of it ?. Something like CRC or similar. I'm not saying it's happening.... but.......

Sam, I have used a product called Inox, it dries and remains there to protect, I have used it on tools and fittings and so far (touch wood) it has worked. Trek can probably supply better information re electrical protection.

samsturdy said..

Thanks Bob. I think this Summer has highlighted the vulnerability of boat electrical circuits to humidity. It would
be really good if there is a product that can help prevent this.

Any spray on substance will dry out eventually and while I am a huge fan of Inox even it will cease to protect as rigorously as what you had hoped for. WD40 is just rubbish for long term protection, CRC is marginally better
Another alternative would be dielectric grease, just slather it on whatever you want to protect and no air or moisture is getting anywhere near that sucker after that.

LooseChange said..

samsturdy said..

Thanks Bob. I think this Summer has highlighted the vulnerability of boat electrical circuits to humidity. It would
be really good if there is a product that can help prevent this.

Any spray on substance will dry out eventually and while I am a huge fan of Inox even it will cease to protect as rigorously as what you had hoped for. WD40 is just rubbish for long term protection, CRC is marginally better
Another alternative would be dielectric grease, just slather it on whatever you want to protect and no air or moisture is getting anywhere near that sucker after that.

Hey, you are correct, inox will reduce in performance but the occasional spray on a regular basis is easy. Most change the engine oil on an annual basis, a quick spray behind the panel when doing the change takes no time at all.

Inox is fantastic stuff for so many things. As well as the spray can you can buy it in a 20 ltr container, Just use a normal spray bottle. A spray can for the boat for convenience, and a 20 ltr container at home decanted into spray bottle for any planned jobs (will even unseize old outboard motors).
That and a can of silicon spray and you're boat toolbox is pretty much capable of everything!

Another vote for lanox, main ingredient is lanolin. There is other products with lanolin, cant remember the brand that i have but it leaves a thin film of grease and its recommended for circuit boards.

cisco said..
Inox is great. Lanox is better. It has sheep fat in it so the coating lasts longer.
You need to be wary of spraying electrically conductive liquid around your switchboard. You could cause a short circuit.
Just an itsy bitsy squirt from a pressure pack can with the tube in the nozzle squirted right on each connection should be enough.

Spraying it all over the back of your switchboard is probably not a good idea.

For non soldered mechanical connections a smear of Vaseline keeps the corrosion at bay. My battery connections have liberal smears on them.

I always have a jar on board. It is good for dried out lips too but it tastes horrible.

A tub of Lanotec is another good thing to have on board. www.lanotec.com.au/

I was a bit wary of spraying anything liquid onto an electrical circuit but I can isolate the switchboard so if
I give it a liberal spray and then wait for it to dry before switching back on ....that'll do , won't it ??.

shaggybaxter said..
Hi Sam,
It pretty much common sense mate. If you spray too liberally and the solution runs like water between electrical connections it will short out. If you spray and then wipe up any residue between the electrical connections so the electricity can't take a path its not supposed to you're ok.

+1 Second this, look at it like any spray painting job, light mist coat over heavy run inducing spray.