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Odd Black Spot On GE F40T12 Plant Light

Odd Black Spot On GE F40T12 Plant Light


Check out the weird black spot that formed on this GE F40T12 Aquarium/Plant bulb LOL

This lamp is wired in series with a F40T12 Daylight lamp, and they're ran on a F96T12 Instant Start Electronic ballast (wired for overdrive)...

The Daylight lamp reached EOL (and probably gave a good EOL show which i wasn't around to see) and the single dark spot you see in the pic showed up on this lamp...it still works just fine though :)

E32_C50.jpg 48B_T6.jpg GPL_SPOT.jpg v40_55k.jpg

Light Information

Light Information

Manufacturer:General Electric
Model Reference:F40PL/AQ Wide Spectrum
Lamp
Lamp Type:Linear Fluorescent
Base:Medium Bi-Pin
Shape/Finish:T12
Service Life:-unknown-
Fixture
Fixture Type:modified LOL
Ballast Type:Electronic Instant Start
Socket Type:Medium Bi-Pin
Electrical
Wattage:40 (but ran at something higher)
Current:430ma (but ran at something higher)
Optical
Lumen Output:-unknown-
Color Temperature:-unknown-
Color Rendering Index:n/a
Physical/Production
Dimensions:48"
Factory Location:USA
Fabrication Date:-unknown-
Application/Use:Growing Plants

File information

File information

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Filename:GPL_SPOT.jpg
Album name:xmaslightguy / Fluorescent Bulbs - 48"
Keywords:Lamps
File Size:31 KB
Date added:Aug 30, 2010
Dimensions:600 x 275 pixels
Displayed:324 times
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Comments
rjluna2
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Robert


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Aug 31, 2010 at 06:57 AM Author: rjluna2
The black spot could be the cathode emission coming out of the the filament. I think the theory goes out when you have coiled coil that you can see through the coiled coil filament, there is magentic field form a loop around the coil. When it does, the emission coating gets knocked loose and the field carried through the magentic field until it hit the glass wall.

Comments?

Pretty, please no more Chinese failure.

suzukir122
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suzukir123
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Aug 31, 2010 at 07:23 AM Author: suzukir122
I have a GE watt miser that did this EXACTLY before it
started reaching EOL. The black spot just grew and grew
until it covered all of the bulb ending. That's when the
bulb did it's EOL. I'm trying to upload the pictures of
it... this could be a small sign of EOL for your bulb...
maybe.

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DieselNut
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John


jonathon.graves johng917 GeorgiaJohn
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Aug 31, 2010 at 12:25 PM Author: DieselNut
I bet that thing caught HELL while the other one in series was flashing/arcing @EOL. Too bad you missed the show! I have seen many times with series ballasts where one lamp reaches EOL and severely shortens the life of the "surviving" lamp. That is an interesting spot though. I have not seen one so small and round. LOL

Preheat Fluorescents forever!
I love diesel engines, rural/farm life and vintage lighting!

xmaslightguy
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^homebuilt fixture


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Aug 31, 2010 at 05:16 PM Author: xmaslightguy
@DieselNut LOL i'm sure it did ... just knowing what a good bright light this is compared to normal (and ofcourse how Electronic IS ballasts finish off lamps (a overdriven lamp @ EOL would probably make for a good video LOL))

@suzukir122 I've seen what you describe where a small spot appears then grows & grows til the whole end is blackened ... so far this one is just staying the same (the other lamp died last week)

@rjluna2 You're probably thinking along the right line there the spot would be lined up about with the filament end ... i'm guessing there was some sorta weird field that built up and caused it to sputter/shoot something through the end of the coiled filament

Colored Fluorescent's such as F40T12 Red or  Green or Blue are awesome...

Alights
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USA (120V 60HZ)


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Aug 31, 2010 at 07:51 PM Author: Alights
that must be hard on the ballast
xmaslightguy
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Aug 31, 2010 at 08:36 PM Author: xmaslightguy
@Alights EOL probably is somewhat hard on ballasts...Just because of where this light is, if i'd realized how close to EOL the lamp that went out was i woulda changed it out it before it died (knew it was getting old, but thought it had more life left)
From what i've read overdriving (with ballasts that can do it) won't hurt...the ballast will a bit cooler than normal because its actually got less current running through it

Colored Fluorescent's such as F40T12 Red or  Green or Blue are awesome...

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