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How To Test If A Projector Lamp Is Bad – Lamp Guide



How To Test If A Projector Lamp Is Bad

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As an average projector bulb may last up-to 2000 hours, so by using your projector 6 hrs a week, your projector bulb may last from 4 to 6 years, but that’s just a rough calculation.

To be really sure about whether your bulb is bad or not, here’s is how.

So in this article we will discuss what to look for or signs of a bad projector lamp.

More importantly, using a projector “mileage” or lamp hours counter to see if your projector lamp needs replacing.

Lastly, we will touch on how to use a multimeter to test for a projector lamp resistance or if the lamp is working or not, this test is not difficulty, easy for a person with no electronics knowledge.

Do check out our other article on Projector Screens making a difference.

Signs that a projector is bad

As with a lot of electronics, components, tend to wear out as time goes, this is true for products like projectors and projector lamps.

With that said….

There are many “small” signs that a lamp tend to give out, indicating that it’s life is coming to an end.

Spots appearing on screen

One such sign, is if spots are appearing on the projected screens, these spots may become prominent or may stand out when the projector is projecting a solid colors like blue.

If you find spots on images given out by the projector, then time is approaching for you to get the bulb replaced.

Lamp Dims

Another most common sign that your projector lamp is going bad, is  that it is dimming as time goes.

Since lamps are not made to last an eternity and are also subjected to “wear and tear”, they will lose their brightness slowly and by the time they failed, they will have lost about 70% to 80% of their brightness.

If your bulb has lost it’s strength, then nine times out of ten, it’s time for it to be replaced.

Flickering lamp light

When watching a horror movie and when lights on a dark passage starts flickering, you know that this would be a scary movie, well same for a projector, when the lights starts flickering, then it’s life has come to an end.

Lamp is blown

The most easiest tell-tale sign to knowing that a lamp is faulty or bad, is when the lamp does not power on, common sense isn’t it? Easiest sign right?

We’ll anyone can obviously see that the projector lamp is not lighting up and that’s when you have to change the projector lamp.

Sometimes the lamp may just blow, not from being worn out, but for other unknown reasons.

By “blown”,, what’s meant, is that the bulbs are physically blown up.

Lamp hours has reached 1500 to 2000

Check your lamp hours on your settings menu, this is the number of hours that your projector lamp has racked up in it’s lifetime.

Although lamp life differs from device to device, 1500 to 2000 hours is what they average, so when they have reached this number, then it’s time to change the lamp as by this time, it would have dimmed, flickered, blown.

How to test if a projector lamp is bad

Now that we have looked at signs that a projector lamp needs replacing, here’s how to actually test the lamp to find out, if they are indeed faulty.

This test is actually easy, may sound complex for someone who is not familiar with electronics, now to test the lamp to see if it’s working, here what we need.

What’s needed?

How To Test If A Projector Lamp Is Bad. Multimeter shown with connectors.

A multi-meter is needed for this test, basically, all we are testing for here is resistance. Resistance is simply the test of an electronic component, to see if the circuit completes or doesn’t.

An incomplete circuit which could be a result of a bad component or in this case, a bad projector lamp.

The idea behind resistance testing, is that, low current is made to pass through the + and – terminals, if it passes successfully, then there is resistance. 

Any person with no knowledge of electronics, should find this task an easy one.

Resistance testing for projector bulb

To test if a bulb is bad, you might need to do a resistance test on it, to do this, this first step is to;

  1. Turn off the power (from the power outlet) and pull the power cord so that electricity current may not enter the projector thus contribute to wrong reading.
  2. Remove the projector lamp casing from the projector, you may need to unscrew the screw that’s holding the lid which has access to the projector lamp. 
  3. Remove projector lamp from the casing, the projector is encased in a cubic encasing, since we only need to access the terminals, we can also leave the bulb in the encasing.
  4. Touch each end of the multimeter onto each terminals.
  5. On an analogue meter, the needle should move and then register 0, on a digital meter, the number should briefly spike. (Basically, upon contact, there should be movement.
  6. Movement of the meter, shows that there is continuity on the lamp and that the lamp should still be working.

Click here to check out some multimeter on Amazon.

So that is how a bulb is tested to see if it’s working or not. 


One of the two biggest signs that a projector lamp is going bad, is when the lamp is dimming or when spots are appearing on the projection.

Since electricity needs to flow from the terminals and pass through the filament, a multimeter should detect if the current is not reaching the other end.

Discontinuity or current not reaching the other end is why the lamp is bad and would need replacement.

But before even opening the projector up, use the projector’s lamp hours counter.

The lamp hours counter should let you know if the life of the lamp is coming to an end and no further testing should be needed.

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