Can defective lamps produce bad colors? - AVS Forum
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post #1 of 10 Old 04-24-2012, 05:59 AM - Thread Starter
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Lamp for Samsung HL-R5667W - Defective?

I replaced a Philips lamp (BP96-01073A(P)) in my TV(purchased 2005). It was losing light output and it had to cool for 45 minutes before the TV would restart.

The color was way off with the new OSRAM bulb. On faces, most often a blotchy yellowish area was on the forehead. In darker scenes, there were severe green blotches surrounding areas and blue blotches also. Some brighter scenes looked normal.

After adjusting the set frequently for about a month, I was seriously thinking about buying a new TV! I put the old bulb back in. The color was back to normal with the old bulb.

I had stored the bulb and it was out of warranty but I contacted the retailer anyway. They are saying that 'it could not possibly be the lamp as the lamp only supplies light and does not affect the color'.

I am researching high pressure mercury lamps and have found -

I have worked with light sources and their spectral outputs although I'm not familiar with these specific lamps. Generally, a gas such as mercury is used. At low pressure the lamps produce line spectra, strong green lines, blue lines, etc. such as those shown on the following site. The lower the pressure the sharper the lines will be. Compare low and high pressure mercury spectra on this site.

http://ioannis.virtualcomposer2000.c...oscope/Hg.html

To get a very broad spectral output, blue to red, the pressure can be increased to a very high level. The lines broadens and the spectrum fills out to look more continuous, more like sunlight. I believe the quartz tube at the center of the lamp is very thick to hold the high pressure.

http://www.projectorlampexperts.com/...facturers.aspx

"Osram projector lamps

Osram's P-VIP lamps are high pressure mercury lamps for use in video projectors, rear projection televisions and other projection applications. The spectrum of mercury in these lamps is altered by the high operating pressure, resulting in a dense, multi-line spectrum which is ideal for projection purposes. Osram lamps give a high luminance, an essential prerequisite for efficient projection devices. Furthermore they excel through long operating life and a low loss of luminous flux during that life span."

If a lamp is defective and loses pressure the spectrum would tend to show more line structure and that should appear in the picture. In fact, the strongest line of the mercury spectrum is the green line as can be seen in the first link. That strong green line might account for why green seems more prevalent in my picture with only the one bulb. ?

Switching bulbs is a simple experiment. The old Phillips bulb produces good colors and the replacement OSRAM does not.

I’d like your thoughts on whether defective lamps can produce this type of color effects and, in general - what is going on?

Also, after turning the set off it requires 45 minutes to cool before it can be restarted. Is there a temperature sensor that needs to be cleaned? Where?
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post #2 of 10 Old 05-01-2012, 08:32 AM
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They are saying that 'it could not possibly be the lamp as the lamp only supplies light and does not affect the color'.

I would have to agree with that.
Overall color temperature can vary between lamps and age, but of have a lamp change a 'gray scale' within a TV image, I can't see how.

I did glance through that link, but that is a little above me.
I can see that overall color temp. could be off, but not that it could affect the low end of the TV gray scale one way and the upper end another. But, I guess stranger things have happened.

How about some screen shots of a gray scale pattern with each lamp?

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post #3 of 10 Old 05-01-2012, 08:35 AM
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As far as the cool down time, what was it when the set was newer? Air path is probably dirty.

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post #4 of 10 Old 05-01-2012, 10:44 AM - Thread Starter
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The old Phillips lamp works great. No color adjustments, just works great. The newer OSRAM lamp is way off in 90% of the sceens. Blotchy areas of green especially in darker parts of darker scenes.

I don't agree. Any light source has a light intensity and spectral output. If the lamp was not properly made or has lost pressure - I stored it for over a year - and if it will still conduct current then it seems likely that the lamp's output intensity and spectrum would change.

""The spectrum of mercury in these lamps is altered by the high operating pressure, resulting in a dense, multi-line spectrum which is ideal for projection purposes." "

I thought that this problem would have been seen before. I am certain the $87 bulb would do the same in another similar Samsung set.

I have read about counterfeit bulbs in the market place - do they just fail and not put out any light?

I wish I had taken a screen shot when the bad bulb was in.
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post #5 of 10 Old 05-01-2012, 10:49 AM - Thread Starter
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Originally Posted by videobruce View Post

As far as the cool down time, what was it when the set was newer? Air path is probably dirty.

Where is the air path and how can I clean it without stirring up dust that would get onto the optics? At least I could remove the lamp which is very open.
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post #6 of 10 Old 05-02-2012, 08:08 AM
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I has a Sammy, but not long. I never had to do any maintenance. Take a look at my "what's inside" thread. (link in my sticky at the top of the forums page)

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post #7 of 10 Old 05-25-2012, 10:03 AM - Thread Starter
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I contacted OSRAM. Got a standard reply with no real interest in addressing my issue.

I put the old Phillips bulb back in the set and it has worked great perhaps a little dark during the day. I learned that Phillips and Texas Instruments originally designed this projection technology together.

(I believe that I had requested a Phillips bulb from River Valley Electronics but they sent the Osram.)

I am wondering if there is a paper trail for orders of TV bulbs that might verify that it was a genuine Osram lamp.

With any bulb it still takes 45 minutes or more if the set is turned off for it to start up again. That is a major inconvenience so we just leave the set on when we are at home. It seems reasonable that dust from fan air over 6 years, as mentioned, is on a temperature sensor. I don't know where to vaccuum and am afraid that dust will get on any open optics, not sure what is open and what is in a sealed assembly.

Anyone know where to vaccuum to clear the temperature sensor?

Anyone know if general vaccuuming will put dust on the optics?
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post #8 of 10 Old 05-25-2012, 11:17 AM
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With any bulb it still takes 45 minutes or more if the set is turned off for it to start up again. That is a major inconvenience so we just leave the set on when we are at home.

It just won't start, or it will take 45 min. to boot back up?
Not a very 'green' situation.

It isn't the vacuuming itself, it's the brushing off of the dust that makes it travel.

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post #9 of 10 Old 05-25-2012, 11:35 AM - Thread Starter
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Quote:
Originally Posted by videobruce View Post

It just won't start, or it will take 45 min. to boot back up?
......................................................

If you turn off the set then it will not turn on again for, say, 45 minutes. Makes a funny escalating pitch noise for a few seconds, stops the sound, then repeats the sound again and again. Once that sound has started the set has to be unplugged or it will continue despite any ON-OFF controls, etc. I don't trust leaving the house with it making the sound and plugged in.

You are suggesting to brush off the dust instead of vaccuuming it?
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post #10 of 10 Old 05-25-2012, 11:50 AM
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That's the ballast, it's bad. Probably after it cools down, the ballast will fire correctly. It should make three tries then quit if the lamp doesn't fire..

You have to brush something off to loosen any dirt/dust attached to it. It how much 'dusting' is dome vs the suction power of the nozzle that matters as to how much flies around.

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