How to interpret fluor. tube colors?

The fluorescent lamp on a Kenmore Model 250 stove (now 20 years old) has started wrecking new fluor. tubes (Sylvania, 22-inch, 18 watts). Symptoms are: 1. Dark grey bars appear at both ends of the new tube within 5 min. use. 2. Tube lights only at the two ends (dark in the middle for 18 inches.) One end shows white light, the other pink light.
What does this mean?
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Don Phillipson
Carlsbad Springs
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Don Phillipson wrote:

The tube is worn out.
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No - New tubes don't go bad that quickly. Sounds like the starter contacts are shorted closed and not openiing after a few seconds like they are supposed to. The warm glow seen by the OP is the heaters staying on because the starter contacts are staying closed more than a few seconds. The blackening is due to the filament material being burned off by the filament staying on. Normally, only a little bit of material gets burned off each time the light is started. When the filament stays on ther material gets rapidly burned off and deposits on the cooler glass where is turns dark. I'd bet a lot of $$ on a stuck starter.
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If the tubes grey-end in five minutes, that's my diagnosis also. Starter stuck.
Christopher A. Young Learn more about Jesus www.lds.org .
No - New tubes don't go bad that quickly. Sounds like the starter contacts are shorted closed and not openiing after a few seconds like they are supposed to. The warm glow seen by the OP is the heaters staying on because the starter contacts are staying closed more than a few seconds. The blackening is due to the filament material being burned off by the filament staying on. Normally, only a little bit of material gets burned off each time the light is started. When the filament stays on ther material gets rapidly burned off and deposits on the cooler glass where is turns dark. I'd bet a lot of $$ on a stuck starter.
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On 11/24/2012 1:18 PM, Don Phillipson wrote:

Starter/ballast gone...
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Don:
I'd phone Sylvania's 1-800 customer service phone number to see if they've had a problem with their small fluorescent range tubes and see what they say. Maybe talk to their tech support people and tell them about the dark grey bands.
Any leakage of oil from the ballast is a sure sign that it's kaput.
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Do I read that you put a NEW tube in, which gets grey ends in a couple minutes of being new?
That's a new one, to me, if so.
Christopher A. Young Learn more about Jesus www.lds.org .
The fluorescent lamp on a Kenmore Model 250 stove (now 20 years old) has started wrecking new fluor. tubes (Sylvania, 22-inch, 18 watts). Symptoms are: 1. Dark grey bars appear at both ends of the new tube within 5 min. use. 2. Tube lights only at the two ends (dark in the middle for 18 inches.) One end shows white light, the other pink light.
What does this mean?
--
Don Phillipson
Carlsbad Springs
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"Don Phillipson" wrote in message
The fluorescent lamp on a Kenmore Model 250 stove (now 20 years old) has started wrecking new fluor. tubes (Sylvania, 22-inch, 18 watts). Symptoms are: 1. Dark grey bars appear at both ends of the new tube within 5 min. use. 2. Tube lights only at the two ends (dark in the middle for 18 inches.) One end shows white light, the other pink light.
What does this mean?
--
Don Phillipson
Carlsbad Springs
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Something here on the topic of fluorescent tube failure. http://en.wikipedia.org/wiki/Fluorescent_light#End_of_life
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On 11/24/2012 1:18 PM, Don Phillipson wrote:

If you there is a starter and if it is stuck both ends should be kinda pink from the filaments. You might evaporate the filament to blacken the ends.
For ballasts that power the filament, if a filament opens (or bad contact to ballast) you can get end blackening at that end. The tube would light, and 5 minutes sounds real fast.
My guess would be starter (if there is one), contacts from ballast wires to socket and socket to tube, then ballast.
You could try sci.engr.lightning. Some real smart people. It is pretty dead now, but some of the regulars seem to still be around.
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