Pool light not working. not typical.

[mbc2237]

Hello everyone,

My pool light is not working. I am not the original owner of the house and it wasn't working when i moved in. I am attempting to fix it. Here is what i have done:

1) checked the transformer voltage...good
2) verify 12V at the light socket...good
3) replace bulb with new.

Bulb will not light when turned on momentarily. Thought it might be a bad bulb so i connected it briefly to a 12V lantern battery. works great. plug it back into the socket...nothing...check voltage again with a meter...good 12 V. plug back in the light...nothing.

Sprayed a bit CRC dialectic into the socket and let dry...repeat...nothing.

I am at a loss. i even had the power on and moved the bulb around in the socket thinking that the socket prongs may be loose. nothing.

More info is that the bulb is a plug in style 12V 75W halogen. If i am leaving anything out, please let me know. and please help! i really don't want to replace the fixture cause they aren't cheap as everyone knows.

thanks in advance!

 

[gwegan]

Welcome to TFP!!!

Do you know the brand and model of your light? Preferably model number.

 

[mbc2237]

Negative on the brand and/or model. It isn't identifiable on the casing anymore. It uses a 75 watt - 12 volt - MR16 - Bi-Pin (GU5.3) Base. It is the underwater niche style housing. From the post above it is a low voltage source. I took a picture of it and attempted to post it. The only reason i believe it is a 75W bulb is because that is what was already in it. The bulbs aren't cheap so i havent tried a lower wattage but from the searches i have done it seems that 75W is pretty standard for the underwater niche lights (at least the older style.) BUT, even if the wattage of the bulb is too high, the transformer is more than capable of pushing that current. It just wouldn't be great for the socket, wiring, etc. So it may be a factor down the road but it wouldn't keep it from lighting.

Sorry...Not saying that anyone said something to contrary...just thinking through the possibilities.

 

[mbc2237]

update...
I tested with some alligator clips at the transformer...bulb lit
test at the junction box where the niche connects...bulb lit
tested again in the fixture...nothing

So obviously it is the actual fixture or the wiring to the fixture. I am not an expert but i did connect my multimeter in parallel with the bulb at the fixture and saw that when i put the load (light) on the circuit, my voltage dropped to almost zero. i am not sure exactly what to expect if there was a rupture in the water resistant cable and i know the conduit is water filled soooo if there was a small leak to ground, would i get the voltage drop i saw?

replacing the fixture isnt the end of the world as far as time is concerned but i am not sure how the conduit is run to know if i would need a 50' cable or longer. AND how many 90's are in the run. it may not be very easy to fish the new cable through. all that AND new light fixtures are sooooo expensive. If anyone can think of something else to try or possible explanations that would keep me from replacing the whole fixture, it would be much appreciated.

 

[lanshark]

I, too, have a flaky pool light, mbc2237. This is the light I have: http://www.poolpartsonline.com/p-288-sta-rite-sunbrite-large-light-parts.aspx

Mine has twice now refused to work for a couple of weeks at a time, then it's OK for months.

I have checked out all of the components from the bulbs to the wall switch in the house and found no problem. The weather doesn't seem to be a factor. All of the electrical connections are tight, and all of the voltages are as expected.

However, there is one variable in my equation, and that's the 120v/12v transformer. I don't know if its characteristics can change, but that's what it looks like to me. If it happens again, I'll replace it.

 

[gtemkin]

It sounds like your socket is the problem. Multimeters probes can touch portions of the socket that the bulb leads don't normally touch and although the multimeter shows voltage the bulb can't see it 'cause it doesn't contact the same portions of the socket. Those style sockets are notorious for oxidizing their contacts from the high heat of the halogen bulbs and therefor making poor connections. The contacts also lose their spring temper from the heat so they don't grip the bulb pins as well. Leads to a death spiral where eventually nothing works. Suggest you get a replacement socket assembly available at most lighting fixture stores. They're pretty inexpensive - about $3 - $5.

 

[mbc2237]

I'll take another look at the socket tomorrow but i don't know how easy it will be to replace because the bottom is full of the epoxy or whatever waterproofing material is used. I think i may be able just remove the socket part as you suggested. Do you know if the big box home improvement stores have them as well? I have a lighting place nearby but when i was in there last, they only had lights...maybe they just dont have them out and i need to ask for a socket specifically? Thanks for the nudge in the right direction though. I'll post back with what i find.

One of the interesting things though is that i took the prongs out of the old bulb and stuck those into the socket and then tested with the multimeter on just the exposed prongs and had voltage just fine. it didnt get flaky when i moved the leads around either. When i used the alligator clips to connect the bulb in that configuration, i still had nothing. i figured that would have worked for sure. i should have snapped a pic to show that setup.

 

[gwegan]

If you can get it out take the socket to the lighting store.

 

[gtemkin]

Many lighting stores have parts in back cause they mostly use them to fix lamps that are brought in for repair. I'd go ahead and ask.

 

[mbc2237]

so it seems that the socket is riveted to a plate behind the socket. you can make out the rivets in the pic. there seem to be 4 rivets. If i pop them off, is there an easy way to mount a new one back in provided i can get one at a lighting store?

 

[gtemkin]

Very good hardware store may have small (#2) stainless steel nuts and bolts which could take the place of rivets.