12vdc Nav Lights

[ksmith]

I have rather old perko nav lights. Starboard runs forward then runs across to port. Starboard lights just fine. Port test between points at 12.78 however when the bulb is installed no light. These are festoon type bulbs, 10 watts, .8 amps and 12 volts.

Any ideas. Feel like I am missing something but not sure what.

[David M]

I'm not sure I understand about "Starboard runs forward then runs across to port"

Are they combined or separate sidelights? Your starboard sidelight works but your port does not? What is the voltage across the pos and neg terminals at the light bulb?

Are the contacts clean and making good contact?

Did you check the bulbs resistance?

[ksmith]

David.

The main wire runs from the panel to the starboard nav light then a set of wires runs under the deck to the port nav light. The voltage across the pos and neg of the port light is aprox 12.78. Will double check some more things. Seems like it should be pretty straight forward. Always worry I have overlooked something obivous

[s/v Jedi]

It's a bad contact either with the wire between the two lights or within the post light itself (like wire to fitting or bulb to fitting). This is assuming that the bulb is good and you measured that voltage at the fitting and not at a terminal block further away.

Just clean the contacts. The reason you measure the voltage is that the meter uses very little (or no) current, which can be supplied through the bad contact. The light bulb however, uses much more and the voltage collapses.

cheers,
Nick.

[Captain Bill]

I'm not sure about your Perko lights but in some sockets the contacts are on a small spring loaded piece of phenolic. If that spring is shot, you'll still read 12v at the contacts but those contacts will never make a connection with the bulb. The easy way to tell is to take the bulb out of the working light and using a small piece of plastic or wood press down on the contacts. If they're spring loaded it will be obvious. If it is spring loaded do the same to the non-working light and see if the spring reacts the same way. I haven't had this problem in a while, but I have had it.

[Randy]

I had those old Perkos and it was tough having the bulbs maintain good electrical contact because the units weren't water tight and the contacts would oxidize.

[Northeaster]

I have the same setup, and had one out the other day. Had 12 v at the connections, so I cleaned the socket and bulb connnection points - still nothing. Bulb looked fine. Changed bulb and worked fine. Tried old bulb - still nothing - shot inside I guess.

Try the bulb from the other side, or a new bulb.

[Ex-Calif]

We have a deck fitting with female and male pin connections. Steaming light was intermittent. Pull the deck fitting, clean the pins, measure the plug voltage ok. Put the plug together. Measure votage at the masthead fitting - OK. Two days later - fail.

Long story short the female sockets were worn out and making intermittent contact. I have temporarily jury rigged by shredding up some tin foil and filling the female sockets. New connectors some day...

I am with Jedi -

- Remove and clean all the contacts at both ends between the starboard and port lights.
- Remove the wire connection from the port fitting - flash the wires manually against a bulb - if the bulb lights the nav light fitting is faulty in some way
- clean the fitting connections - check the fitting to bulb contacts for corrosion and tension against the bulb

- Don't rule out dirty connections, wiring, nav light fitting.
If that doesn't do it you have an open in the wire somewhere and need to run new wires.

[pasogrande]

Throw out the Perkos and get Innovative Lighting; they are LED with two mile visibility.

[David M]

For now you can put a little silicon grease over the electrical contacts to slow down the corrosion.