Electrical Conundrum

[NateD]

This is the strangest thing, I'm hoping someone else has seen this before and knows how to fix it. I have an Aqua Signal light at the top of the mast. The anchor light works, but the navigation light does not. When I take the light bulb out of the socket for the navigation light, and put a volt meter on the socket contacts, I get 12 volts. When I put the bulb in, it does not light up. When I put the volt meter to the back of the socket with the light bulb in, I get no voltage. When I take the bulb out and test on the back side of the socket, I get 12 volts. So, when there is no bulb in the socket I get 12 volts across the socket terminals (whether tested on the actual light bulb contacts, or on the back side of the socket). When I put a bulb in, suddenly the socket has no voltage. It's not the bulb, I tried different ones. I jiggled the wires that lead to the socket, but it made no difference. Any ideas?




This is the inside of the socket. Those contacts get pushed down when the bulb goes in.


This is the backside of the socket. When there is no light bulb in the socket I get 12 volts across the two little screws in the middle of the screen.


Now with the light bulb in, I get no voltage across those terminals and the light bulb does not light up.

[Pat McL]

Hi Nate

I have had a similar problem, albeit on a much older unit. In my case, the phenolic disc in which the two contacts are spring mounted started to slip off from center so that when the bulb was mounted, the contact(s) would slip and lose contact with the bulb. Also, when the contact was compressed, I got an infinite resistance. Easier to replace then repair --- too hot to sail today here in FL, 100.2 degrees!!  --- Pat

[Brian 1851]

Hi Nate,

     It looks like in your second picture, the one with the socket, that the one contact is pushed in relative to the other.  So your light won't light unless you have good contact with both contacts in the socket to the light bulb.  At least that's what it looks like from the picture.

[Craig Weis]

This is going to take some thinking. And I'm out of time at this moment. But I'm thinking that one or the other need to be switched on. Nav light 'on' no power possible to Anchor light.
With Anchor light 'on' no power to the Nav light.
This complies with U.S. Coast Guard lighting rules.
Separate circuits? skip.

[Brian 1851]

Nate, hi again.  To check and make sure you have good contact from your hot wire, through socket contacts, through bulb, contacts again, and back to the other hot wire you can do this.  If you have an ohm meter setting on your meter put it on that.  Then put you leads on both wires.  You should either get OL which means something between the two wires is not making good contact or something like 1 or less showing at least that you have good connections between both wires.  Do this with your power off to the light.  I hope this helps.

[Steve Ullrich]

Nate - Not sure who wired your mast head light, or how you are wired, but Skip is correct.  Your anchor light can't be on when you are under sail.  You can't be showing a white light off the bow.  Your running lights should be on a different circuit/switch.  Also true: When you are at anchor you don't want the running lights on...

[Brian 1851]

Nate,

     You might want to check your fuse for the navigation light.  If you haven't done so already.

[NateD]

Thanks everyone for your suggestions, but I still can't figure this one out.

The anchor and navigation lights are on separate circuits, and work independently (I had both of them on just to reassure myself that there was still juice in the battery and that the light bulbs work). When I have both switches on I find 12 volts on both circuits in the cabin before the wires go outside. When I test the wire connector on the outside of the cabin, I get 12 volts. When I go to the end of the mast with no light bulb in the socket, I get 12 volts on both of the sockets. Then I put the light bulb in for the anchor light, it lights up, and the navigation socket still reads 12 volts. Then I put the light bulb in for the navigation light, and it will not light up, and testing across the terminals on the back of the socket shows no voltage.

I have to believe it is something with the socket for the navigation light, because I can track the voltage all the way to the that point, then when I put the bulb in I can't even get voltage across the terminals.

Brian: I think one contact on the back of the socket looks longer because of the angle, but I'll check that. My next test will be continuity through the socket with the light bulb in, that's a good idea.

Pat: How did you figure out that the socket contact was slipping off the light bulb when pushed in?

[Steve Ullrich]

Nate,

How does it test with a meter when you have the anchor light off and the running lights on?

[Craig Weis]

Run down to AutoZone or some auto parts store and pick-up a 12 volt test light.
Has an alligator clip one end and a needle probe at the other end with a lamp in between.
Take your battery charger and fire up the system and then go fishing for electrons
running around on the wires. Make a drawing if you have to. Might have to put a small
nail on the alligator clip if power needs to be taken from a female contact down inside a
connection.
skip.

[Goodrun]

Voltage is just pressure. Pressure can build even when there are other things in the system that have a high resistance. You need amps and volts to power the bulb. No amperage = no power.  Some resistance in the circuit is using up the voltage before it gets to the bulb. You need to troubleshoot the problem using voltage drop. The theory is that the source voltage should be nearly equal to the load(bulb) voltage in a perfect circuit. In your case the bulb voltage is zero when plugged in. Assuming that your battery (source) is at 12 volts then some other resistance in the circuit such as corrosion is using up the voltage. With the bulb plugged in, check across the fuse, switch, base connection on the mast etc. When you find the culprit it will read voltage. In other words if you find 12 volts across the switch with every thing turned on then you have a bad switch. The switch should read 0 volts drop and all the volts should be dropped across the bulb. In a good circuit the bulb would read 12 volts across the backside when it is working properly.

[NateD]

Well, I found the problem today. I've been fiddling with the thing on and off since the first time I took the boat out this year. Man it feels good to finally solve it. I won't go through all of the trials and tribulations, except to say that no matter where I tested in the circuit, it read the same voltage (12.2v, my battery was a little low), but any time I put a load on it (navigation light, test bulb) the bulb would not light. The problem ended up being corrosion on the male (mast side) of the through-deck wire connection. In the picture you can see that the terminal the red wire is connected to has a lot of green junk on it compared to the black ground terminal. I pulled the wire out, cleaned up the terminal, cut back the wire a bit, fastened it down, and boom, everything works.



Now that the light works right, I thought it deserved a proper mount as well. The previous owner had used stamped steel book shelf brackets to mount the light to, then used sheet metal screws to attach it to the top of the mast. Constant bouncing while towing put a crack in the shelf bracket, which left the light barely holding on the last time we were on the water. So I got some 3' pieces of aluminum ($25, that stuff is pricey in small quantities), made a proper bracket, then riveted the bracket to the mast. Hopefully it is there for good now.

Here is a pictures of the old and new brackets.






Thanks again for everyone's suggestions.

[Steve Ullrich]

Nice job Nate.  Rember that my steaming light didnt' work when we were out on Leech?  I pulled the bulb and it is good. I tested the wiring to the plug at the base of the mast with a VOM. I have continuity, should work. I'm going to clean up all of the contacts and give it a whirl, might be the same problem.  Thanks.

[Craig Weis]

The Com-Pac 19 season starts out by using the battery charger and it's wired up to every lite that I will not be able to reach once the 'stick' goes up.

Usually I need to pull the cabin top connections apart to make contact. Like for in the picture below from the post below. Even with automotive bulb grease. Hey my 1930 Ford Model A B-40 Roadster has a much better track record in the electrical department.

The boat lamps always work "battery charger to wire", but not "battery charger into connection". Just part of fitting out I guess. The sockets 'up top' have always been good.

Additionally:

The start of this 2009 season the battery and it's complex rat's nest of wiring was cleaned up.

Looking around the junk pile in my garage and finding a bunch of wiring blocks for a typical 660 volt 3 phase motor control starting panel that I use to build, I simply snapped assembled 12 contact blocks together for the positive wires and 12 blocks for the negative wires. Each snapped together block is about 5" long and 1-1/2" wide and sticks out from the plywood less then 3/4". So there small.

These blocks were just wood screwed, one above the other, into the storage side of the quarter birth plywood bulkhead with the battery box an inch away away from the blocks when strapped down.

These blocks have pinching screws...what you do is snip off the old ring connections that use to pile up on the battery posts, shorten the wire to length, strip off the insulation about 3/8" and place into the wire pocket and screw down the tiny screw...locking that one wire into that one block.

All the terminals are festooned together with looped wiring which makes each terminal block + or - .  
A very neat set up. But does expose the wiring. A NO NO if you expect to pass a Vessel Safety Check.

But the cool thing is one stout wire from each block to each battery terminal. No rat's nest atop my battery and a very easy two un-wire battery disconnect at the end of the season. And I guess if any additional 12 volt items are to be added there are extra open screw down pockets for wires to be had. I can't find a use for all 12 but snapped in a few extra 'for the wife and kids'.

I embellished my battery box lid by mounting a ON-OFF quarter turn Farm~Fleet kill switch to it. All power off when the boat is a dock queen with one exception. With the kill switch in the OFF position the + and - wire from the solar cell still trickles into the battery.

Oh and one more thing as well. The top-o-battery box has Farm~Fleet battery charge indicator with three green LEDs for 'full'~'2/3'~'1/3'~and 'red charge' LED indicating a dead battery. So you can monitor your battery use and shut off consumables like GPS, Fish Finder, or CD/radio before running out of juice. Like if you feel that you'll be a little late returning to the dock or mooring ball at night and you feel Navigation lights are a good thing. I have LED Navigation lites as well..
skip.