Tip & How-To about Audio Players & Recorders

Kitchen Table Investigation, Projection Lamp, Course 101

Mercury Vapor lamp... how does it work? How do you know when it's bad? I'll try to shed some light on this topic. *Caution: material for the curious follows.

First, let's cover the basics: How it works.

A Mercury Vapor is a mix of electro-chemical and some mechanical ingenuity. Although some may not agree with me, I will state my case anyway. The lamp has a few basic parts. The reflector, which we all see, is used to direct the light in the intended direction... forward. Within the reflector, we have the actual bulb. The bulb contains the burner, mercury, and a fluorescent element. The width of the burner gap is critical for initial and sustained ignition of the lamp.

When your turn on your projection TV, a power supply devoted to the lamp (known as a ballast) passed about 300+ volts of high energy electricity through the lamp, but only for a few seconds. This energy arcs across the burner and vaporizes the Mercury. With the Mercury vaporized, the mercury is now free to move around within the bulb. The power supply then switches into a driving mode and begins feeding about 10,000+ volts at a lower energy. This allows the arcing between the burner gap to continue. The mercury, which is excited by all the electrical activity, begins to slam into the florescent element. In turn, the element glows brightly.

So, that's basically how it works... but what you don't see is the damage. At one time or another, we have all plugged something into the wall and POW... sparks fly. If you had looked close at the plug, you may have noticed some pitting or damage from the spark. This is an electrical arc. The same thing is happening inside your lamp, on a smaller scale. Each high energy ignition causes material to be worn away from the burner. The lost material builds up as contamination within the bulb and the loss of material causes the width of the burner gap to grow.

Some maybe wondering... "Is there a secret formula for extending my lamp's life?" The short answer is: "Stop watching it." The long answer is: Never leave your TV on when you are not watching it; Allow your lamp time to cool before turning it back on (5 minutes to be safe); Allow your lamp to reach it's optimal temperature before turning it off (20 minutes to be safe).

Now that we have that mess cleared up, on to the discovery section of this article: "How can I tell if my lamp is bad?"

Well, in most cases, there are warning signs: Picture is getting much darker; Seems fine at first, but then goes out and comes back on in a moment; Turns off after a period of time or doesn't light at all; I heard a loud pop. All of these are classic warnings or indicators that your lamp may need some attention.

You should allow your TV is cool for about 20 minutes and pull out wall plug and then remove the lamp for inspection. You will need a well lit area to get a good look at it. Do a once over: Did the bulb burst; Does it look smoked up? If it looks good, have a glance at the base of the burner:

Does it have a smokey mark on one side? This is the contamination from the burner gap. This contamination builds up throughout the life cycle of the lamp. As the burner gap grows, the lamp resists the electricity that is be pushed to it to make it burn. This resistance creates heat. Some lamps will create so much heat that the glass surrounding the burner will begin to melt and swell. You may look into your lamp and see a big silvery blob protruding from this area. These are all clear indicators of trouble in the works.

Unfortunately, some lamp show no visual signs at all... for these, you can only replace them and hold your breathe.

I hope you are able to use this information to better guide your lamp purchasing decisions. Let me know it this was helpful.

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2 Answers

I replaced the lamp. now I have discoloration, Red on top and blue on the bottom

Your TV is an LCD rear projection type which requires a Mercury Vapor lamp. Mercury Vapor lamps emit UV light which is damaging to many materials. The discoloration you are seeing on the screen is the UV damage that has resulted over time to the LCD panels within the “Optical Block” (aka projector) of the TV. This discoloration has been creeping up on you for sometime, it just wasn’t as noticeable until you changed the lamp. Once you installed the new lamp, the UV light is bad at full force and the damage progresses at a quicker pace, due to the already weakened state of the LCD panels. Additionally, the picture is now brighter, exposing the damage for you to clearly see. The only fix for this problem is to replaced the Optical Block… an expensive repair. Although this is not good news, I hope this helps you understand the cause & solution and was of some assistance.

Mar 25, 2010 | Sony Grand WEGA KDF-50WE655 50" Rear...

1 Answer

i turn the power on and it tries to come on three times in a row and then shuts off

Having in mind that a generic lamp will give you 4500 to 6500 lamp hours and the Phillips will give you 6000 to 8000 lamp hours and that you TV is 4 years old more likely you are looking to replace you lamp;The lamp itself typically uses AC current and about 15,000 volts to ignite the lamp's mercury vapor gas. The gases inside the lamp react when electricity charges up the mercury gas creating very bright light. The voltage drops to keep the flow of electricity to the lamp.
You can check DM;
RCAs are known for bad color wheels and power supplies, which power your ballast, which powers your lamp,
If you can hear your TV fan working is NOT you power supply,but if you hear a constant clicking you ballast needs to be replace,
A ballast is an electrical component used with a fluorescent bulb (or mercury vapor lamp or arc lamp) to conduct electricity at each end of the tube. It supplies the initial electricity to the bulb that creates light, and then it regulates the amount of electricity flowing through the bulb so that it emits the right amount of light.
You can find your parts at:http://www.discount-merchant.com/SearchResults.asp?Search=HD50LPW175?Click=48426
I hope this will help,please keep us posted.

Oct 01, 2009 | Televison & Video

2 Answers

Lamp resistance and voltage

1. Projector lamps use customized ballasts that ignite the lamp by charging it with a higher voltage in the ignition phase and then dropping down to a lower running voltage once the circuit is created.

2. Projector lamps CANNOT be tested with an AMP or OHM meter. Projector lamps function by igniting ultra-high pressurized mercury vapor across an ARC tube. At the point where the mercury vapor resides there is no conductive electrical material and therefore testing a projector lamp with an AMP or OHM will not work.

Jul 22, 2008 | InFocus Replacement Lamp Projector Lamp...

2 Answers

Continuity test for a projector lamp?

2. Projector lamps CANNOT be tested with an AMP or OHM meter. Projector lamps function by igniting ultra-high pressurized mercury vapor accross an ARC tube. At the point where the mercury vapor resides there is no conductive electrical material and therefore testing a projector lamp with an AMP or OHM will not work.

Jul 21, 2008 | Samsung - Projection TV replacement lamp...

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