The Difference Between a Projector Bulb and a Lamp

You might think that the terms ‘projector bulb’ and ‘projector lamp’ could be used interchangeably, and you’d certainly be forgiven for thinking so. However, they’re not in fact the same, and it’s important to know the difference between a bulb and a lamp before you buy the wrong product.

Simply put, a lamp consists of a single bulb that includes a reflector and cage – also known as a lamp housing. On the other hand, a bulb is just one part of the lamp. Think of it in this way: a lamp is similar to an ink cartridge, whereas the bulb would be just the ink.

An Introduction to Relamping

You might hear other projector owners use the term ‘relamping’. This is the process of fitting a new bulb into an existing lamp housing. This can be performed by either a third party or by the end user. Some people believe that relamping can result in a lower spend compared to buying an entirely new lamp assembly. There are two relamping products available on the market: relamped lamps, and bare bulbs. This is why it’s vital to know the following difference between a bulb and a lamp:

• A relamped lamp is an old lamp housing that has been fitted with a brand new bulb. The installation process is the same as for a new projector lamp assembly – operation involves simply plugging it in.
• Installing a bare bulb (do-it-yourself relamping) involves very carefully fitting the new bulb into the housing of the old bulb. The housing is then plugged into the projector.

While relamping may sound like a great idea, there are several risks involved.Relamping can result in a negative outcome as well as a higher expenditure of both time and money when compared to purchasing a new lamp assembly.

What Makes Relamping “Bad”?

• You could cause damage to your existing projector
• You may void your manufacturer’s warranty
• There’s a higher potential for decreased lamp life
• The process is both time-consuming and involved

There are some cases where relamping is required, such as if you own a Zenith projector. The Christie brand offers relamping instructions and tools that allow customers to save money on several of their higher priced models. However, the term ‘relamping’ typically refers to using an off-brand bare bulb instead of a reputable name-brand bare bulb.

All in all, it sounds like an easy and inexpensive way to do things, but you should be aware of a few things before going the DIY relamping route.

Precautions to Consider When Relamping

1. Information that outlines which bulb is compatible with each projector isn’t always correct – nor is this information always published by reliable sources within the industry. It’s similar to researching information on the Internet – you can’t trust if the information is accurate, or if someone is making it up and just calling it factual. A good example relating to projectors is the part references between Philips/OSRAM bulbs, and name brand projector lamps. These references are known by experts within the industry as being untrustworthy.
2. Bulbs that are sold separately, without a lamp housing, can sometimes seem more costeffective. However, they’re usually sold from obscure vendors or websites who do not provide information regarding where the bulb came from or if it’s even reliable. Relamped lamps also have a higher rate of DOA (dead on arrival) and blow-up, partly due to being moved around during transport. To put it into perspective, imagine you’re holding a normal light bulb. Now, throw it up and down like a ball, shake it, and jiggle it. Now, what do you think the chances are that all the tiny parts inside the bulb are still intact or as sturdy as they previously were? Slim, of course. It’s likely that you’ll now have a bulb that either won’t work at all, or won’t last long once usage has begun.
3. When purchasing a new bulb to insert into an existing projector lamp housing, you’ll need to undertake installation yourself. By relamping yourself, you run the risk of damaging the bulb and the lamp housing, as well as voiding the warranty of your projector. If this does happen, the cost may turn out to be higher than simply buying a new lamp and housing. It’s also worth noting that re-lamped housings are old and have experienced wear and tear that can cause problems. The connectors can twist together and overlap, leading to the lamp and projector being short circuited –a massive electrical hazard. Connectors can also become worn and depreciate in quality over time. This can affect the stability of the electrical supply, causing image flickering and sometimes even permanent damage to the projector.
4. In order to remove the bare bulb, the lamp module must be taken apart. This is often something that manufacturers have not planned for, making it a difficult task. Usually, relamping requires special tools that most people will not have at their disposal. These tools should only be used by professionals in a controlled environment that’s airtight to prevent dust. Most projector lamp housings aren’t designed to give easy access to the bare bulb. Because of this, they have to be broken open during replacement. If the housing is broken, the plastic can be difficult to rebuild, and it’s often impossible to restore to its original condition. This means the lamp module may no longer fit correctly into the projector, causing improper focusing as well as posing a fire risk. Even if the housing remains in a good condition, the bulb will have to be jigged or lined up perfectly inside the housing for the projector to display its image properly.
5. In addition to the issues involved in purchasing and installing a lamp, there are potential health risks involved with relamping. Projector lamps contain mercury, which is very poisonous to humans. During replacement, there’s a risk of damaging the old bulb while taking it out of its housing. If the bulb cracks or breaks, mercury can leak out. The risk of spilling this can cause serious health problems to those who come in contact with it. Proper disposal of mercury is recommended for your health and for the safety of anyone else who may come in contact with the discharged lamp.
6. When reusing the same lamp housing for a long period, dust particles can build up around the bulb and module. These particles are difficult to completely remove, even for an experienced engineer. The dust particles will cause extra heat to be retained within the housing, disrupting the airflow that cools the lamp. This can severely shorten lamp life and cause the projector to overheat or malfunction. A fire hazard is also another risk.
7. Another consideration to keep in mind is what to do if the lamp doesn’t work once it’s been connected. You can’t call a lamp repair man to take a look, as there’s no such thing. You can’t even ask anyone you know, because chances are they know little about projector lamps. Relamping can be quite a gamble, and you have to weigh up the chances that it will be unsuccessful. We recommend sparing yourself the trouble and chance of failure by instead purchasing a brand new lamp. Buying new will be trouble free and guaranteed to be satisfactory.