Appliance Bulb Filament Continuity

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On Sat, 21 Feb 2009 15:08:42 -0500, Charlie Darwin wrote:

I just had an auto light like that. The problem was not inside the glass, but between the glass and the mount. That is quite high for a bulb.

Continuity means it should work. No continuity means it is broken. End of story.
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wrote:

If you flick the bulb with your finger, you may see the filament vibrate, usually only on one side of the break.

What happens when you touch the meter leads to each other?

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The filament is circular going around the circumference of the glass and is supported by 5-6 separate wire posts -- each topped with a loop to support/lock the filament wire.
When touching the meter leads together-- the needle deflects all the way showing continuity.
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wrote:

It still might vibrate when flicked. Depends on where it breaks.

Then your lightbulb is bad, whether the filament vibrates or not.
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Charlie Darwin wrote:

Hi, Anything is possible. Is there proper voltage across bulb socket when door is open?
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Charlie Darwin wrote:

Bulbs have a built in fusible link in the base. The filament can look fine and the bulb not work.
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Van Chocstraw
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Van Chocstraw wrote:

Could be, but I'm pretty sure that ALL bulbs don't use a fusable link in the base.
Sometimes the filament will open right where it's welded to a feed wire and stay in position so it looks like it's continuous. Giving the bulb a flick with your finger while observing the filament will let you see it it jump away from the feed wire momentarily.
BTW, the fusable link was/is placed in some bulbs to avoid popping a breaker or fuse if the bulb goes into a "tungsten arc" mode when the filament opens. That arc can cause the bulb to draw MUCH more than it's rated current. If you've ever flicked on a light switch and had the bulb give one VERY bright flash and then go dark, you've witnessed a tungsten arc.
As you've been told already, try a new bulb.
Jeff
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Jeffry Wisnia
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