How to tell if a lamp is bad? - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 17 Old 04-07-12, 06:01 PM
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Re: How to tell if a lamp is bad?

I have an Optoma EP708 with a lamp that has been run for 7,000+ hours well over 5,000 hours passed the 2,000 hour rating and it still works well.
Should I replace it?

It has been a few years but I am nearly certain it was far more visible in a lit room during the day when it was first purchased. It is around 4 years old.
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post #12 of 17 Old 04-08-12, 06:51 AM
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It depends on what you consider bad. It surely has much lower output than new and worse color. There is no good/bad test other than whether it lights up and comparing the spectrum to a new lamp.




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post #13 of 17 Old 04-08-12, 10:08 PM
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At that point, I'd start thinking about replacement. No huge rush, but you definitely got your money's worth out of that bulb. Save it though until you have about 100 hours on the new bulb in case it fails early (a common time to fail if the new one is bad)
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post #14 of 17 Old 04-14-12, 07:16 PM
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Re: How to tell if a lamp is bad?

I notice sometimes after about 20 minutes the color starts to wash out and I have to adjust some settings. Sometimes it can take a couple hours and sometimes it doesn't happen at all. I suspected new bulbs run a risk of early burn out which is one of the main reasons I want to replace this one while it still works.

I think 3,000 hours is the sensible time for replacement.
I am currently at 7,040 hours and will replace it when I can.
I bought this model because multiple reviewers with much more expensive projectors who had this as a backup said it was the only unit under 2 grand that could compete with theirs.
Something to think about for anyone deciding on an older, used model.

Hopefully someone starts producing SMD's that can match a 200 watt halogen. I have a couple automotive SMD bulbs that match a 50+ watt halogen and work regularly with LED's as I earn my electronic engineering degree so I know it is possible
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post #15 of 17 Old 04-15-12, 05:32 AM
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Re: How to tell if a lamp is bad?

Color washing out generally has little to do with a lamp, other than the brightness increases as the lamp warms. In your case, if you have exceeded the expected life of the lamp so much, it may be that the brightness is actually dropping after warmup.

More likely you are seeing thermal effects on the light path or on other parts in the system. Can you describe what you are seeing that you call washing out the color?




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post #16 of 17 Old 04-15-12, 06:44 AM
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Re: How to tell if a lamp is bad?

Let me clarify my comments above.

Washed out color is usually meaning a lack of saturation. In this case, it may mean a lack of contrast, which certainly could be a weakening lamp. The normal output trend is for a lamp to actually increase in output, resulting in greater contrast, as it warms up. Aged lamps can often take a while to reach peak output. A very old lamp like this one may behave differently.

So it would be unusual for a projector to actually lose saturation as it warms up. This would not be a typical symptom of a bad lamp. What does happen often is that filters in the light path begin to break down, or oils and dust tend to bake due to heat, causing optical properties to change, or electronics heat up and misbehave. Since I now see that this is a DLP, the light path issues are far less common than with LCD projectors (where they are VERY common), and the higher probablility for a true lack of saturation or loss of blacks is with something getting hot, such as the DMD board, or a problem in a power supply such as the very pervasive problems with bad capacitors.

Bottom line here is that the lamp in this latest discussion is far beyond its expected life and may not behave typically. If the problem is that it is getting dimmer after running a while and that is what is meant by colors washing out, changing the lamp is a likely solution. A better description of the symptom would be useful in troubleshooting, however.




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post #17 of 17 Old 11-04-15, 03:29 PM
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Re: How to tell if a lamp is bad?

There is no light

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