Mast lights not working

[yerffoeg]

Last year I rewired my mast and put on new lights. Last weekend got everything rigged up. The tricolour on the masthead worked fine but the combi steaming/decklight is not working. The three lights have a positive feed each, but use a common ground. I have a multimeter, but seek your advice on the most logical way to track down the fault.

 

[Norman_E]

If the masthead light works and the combi light has two bulbs (neither of which light) and therefore two switched positive wires the fault is most likely in the connection of that unit to the common ground wire. The latter must be OK if the masthead light works. The multimeter will tell you little from deck level, and it looks as if a trip up to look at the combi light unit is called for. Before going up however it might pay to check the power supply to the switches.

 

[pvb]

Disconnect the ground. Then check for continuity between the two positive feeds to the steaming/decklight - if there's continuity, you'll know that (a) the bulbs are OK and (b) the positive wires are OK, and therefore that (c) there's a fault with the connection to the common ground. If on the other hand there's an open circuit, it could be bulbs or wiring.

 

[VicS]

If they are plugged into deck sockets suspect them to start with, in any case check the supplies there to decide if the trouble is inside or outside.

OTOH if the wiring comes through glands to an inside junction box check the supplies there.

The trouble with using a digital multimeter is that it take so very little current that you can get a normal reading through a very poor connection. IMHO a small bulb in a holder with a pair of leads can at times be much more useful.

 

[Spyro]

On the multimeter set it to volts scale. Connect the black or negative lead to good know earth which you should be able to find somewhere at the mast as you say it's common and your masthead is ok. Now with the lights switched on tap the red or positive lead onto the switched side of the bulb holder connection. you should get a 12v reading. If you don't start working your way back along the path to the switch. until you get 12v.
If you do get 12v at the bulb holder you have a duff bulb or a fault on the earth side of the light. You can then use the multimeter on the ohms scale and check for continuity between your good known earth and the one on the light.

Hope this makes sense. It does to me.

 

[purplerobbie]

I fitted a new tricolour to my albin vega.
The mast was going up later that day and a friend came to give me a hand. I had left the tricolour till last so it couldnt get damaged in the yard.
Trying to get it right in the middle of the mast while the mast was on its side on the ground was not easy and what made it worse was i had someone saying in my ear all the time "the crane is here to put the mast up hurry up"
Got it on safe and sound then put the mast back on and sat back to admire my handy work only to notice i had put it on back to front!!!


Rob

 

[yerffoeg]

Thanks for the excellent replies. My sympathies Rob - I've been there.