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Thread: Two F4T5/CW bulbs failed

  1. #1
    Computer Programmer Bill Arden's Avatar
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    Default Two F4T5/CW bulbs failed

    I bought three of these small 4W "under cabinet lights" (W-mart, Lights Of Am...) Model 7104

    I am annoyed to say that one bulb failed after a month and another after two months.

    The filament is open on one side with a dark color on the bulb.

    Replacing the bulb fixed the light.

    I am trying to figure out why the filament would fail as I had these lights are on all the time (24/7 path lights to let me leave off the main shop lights)

    I am tempted to take one of the lights apart to see if they used a "continuous run" capacitor type circuit to heat the filament using the main Square wave output.

    Edit: Yes it does use a "continuous run" filament circuit just like the cheep CF bulbs.
    I'll hook it up to the scope to see if I can add a Neon bulb starter to it.

    Edit again: Nope. The light needs the filament to be hot in order to keep it light.
    Last edited by Bill Arden; 01-19-2008 at 01:33 PM.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  2. #2
    Like an engineer alternety's Avatar
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    Default

    Think LED.

    I am not fond of LOA either.
    Last edited by alternety; 01-20-2008 at 11:04 AM. Reason: add LOA

  3. #3
    Plumber jimbo's Avatar
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    Default

    Philips rates an F4T5 at 6000 hours life, about 6 to 8 months@ 24/7. Rated life is the hours that ONE HALF of the population of bubs is expected to achieve. Half will be less, half more.

    LOA makes crap, so I would not expect any of their bulbs to last all that long. They do also warrant their bulbs and fixtures, so you might give them a call.

  4. #4
    Computer Programmer Bill Arden's Avatar
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    Default

    The start cap in the unit was 3.3nF.

    This seems high since the start cap for a 13W CF is around 2.2nF

    Testing shows that 1nF is enough to start even the older (darkened) bulb.

    I wonder if they used the wrong capacitor ?
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  5. #5

    Default Buy a new fixture

    Lights of America are crap fixtures, yes they are cheap but you get what you pay for. I would buy a new fixture.

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