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If the ghost coil image is overlapping the real coil image, as above, the heat from the filaments will be more intense on coils and the lamp glass.

This shortens lamp life and can cause blisters.

Although the two images are not properly aligned they do not overlap.

This is quite OK and often as good as you will be able to get it.

Correctly adjusted the real and the ghost images will align horizontally.

The ghost image will be interlaced with the real coil image, such as illustrated above.

How to adjust projector lamps to get the best light output and to prevent premature failure!

The most important factor in prolonging lamp life is making sure it is correctly fitted and adjusted.

With slide projectors an incorrect lamp adjustment can significantly shorten its life, and in some cases the lamp may even explode or shatter.

8mm movie projectors usually do not require the lamp to be adjusted, but if an adjustment is provided it is there to ensure the most light through the tiny film aperture.

When purchased new slide projectors always came with a lamp adjustment slide or plate with a small hole in the centre.
In many cases this important tool has long since been lost, but you can easily make up a new one - see side bar >>>

Checking the lamp adjustment:

As well as the  ‘adjustment slide’ you also need a small piece of stiff white paper.

Insert the ‘adjustment slide’ into the projector, either via the single slide editor or via the slide tray.

Switch the lamp on and hold the piece of white paper directly in front of the lens.

You will see two images of the lamp filaments projected onto the paper. One is the ‘real’ filament image and the other is a ‘ghost’ image (reflected by the mirror behind the lamp.

Any adjustment required is determined by the position of the ghost image relative to the real image.

If the images look like you see above it usually means that the lamp is not sitting properly in its socket.

It may be slightly tilted to one side, or the mirror or socket not centred.

Here the ghost image is overlapping the real image. This usually means an adjustment is required to the mirror position.

But it could also be that the lamp isn’t fully down into the socket.

Correctly adjusted the real and the ghost images will align vertically, and there will be a small gap horizontally between the two images, such as illustrated above.

First let’s see how the small halogen lamp, used in most modern slide projectors, should be adjusted …

This type of lamp gets quite hot and has an expected / rated burning life is about 25 hours. If this lamp is poorly adjusted it can develop blisters due to overheating and eventually it will fail, or even explode.

See this page for details and pictures of lamp failures.

Because these lamp types are now very expensive (and hard to obtain), it is even more important that it is properly adjusted. By taking care to adjust the lamp, not only will it provide brighter light output, but is also likely to last longer than its rated life.

As mentioned earlier, there is no standard method of adjustment. If you happen to have a user manual you will often find the details here. Failing that look for screws in oblong holes (meaning the screw is meant for adjustment) on the sides or bottom of the projector.
It is usually the lamp socket and/or the reflecting mirror that is adjustable.

Then try to adjust the lamp as shown below.

AND FINALLY - A WORD OF CAUTION:  

Adjustments can usually be reached without any dismantling. However, if you have to remove the covers in order to reach the adjustment screws, be aware that dangerous live power wires may be exposed.

This is especially so with very old projectors, where electrical safety concerns seemed to be of less importance.

Personal safety comes first! Know what you are getting into and always use a commercial power tripping device between the power supply and the projector.

If the power cord and plug appears damaged or cracked or the cord is in poor shape, please reconsider using the projector, or at least have a professional look at is.

Adjustment of tungsten multi-coiled filament lamps - probably more important to get right due to the high cost of replacement lamps.

This is an actual image of an adjusted lamp, and usually the best adjustment you can expect.

The important thing to note is that the wire coils interlace.
This in turn gives better lamp life and at the same time a brighter screen image.

How to make a new lamp adjustment plate:


A small piece of aluminium or other metal (or even a piece of stiff opaque cardboard), about 1-2mm thick, can be used to make the tool.

 Either cut it to the size of a slide frame (50x50mm), or as a small rectangular piece to fit inside a slide mount.

 Drill a small hole, about 1mm diameter, in the centre of the plate.

You now have a tool that will help you check and adjust the lamp position.

There are several ways to make adjustments. Unfortunately there is no standard method used by manufacturers.

In Kodak Carousel there are two adjustments readily accessible after opening the lamp door - one adjusts the lamp and the other the lamp mirror.
In some Hanimex projectors screws are can be accessed from the top, but with many other brands it is less obvious and often you have to remove the top cover for access.

The clue is to look for a screw, a lever or a tab that will shift either the mirror or the lamp socket, or both. This could be inside near the lamp housing or on the base or side of the projector.

The aim is to adjust the projected filament image as in the 3rd image below.

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Lamps for this type of projector are now hard to find and the cost is very high. It may be a better option to purchase another projector with halogen lamp.