Most projectors are air cooled and it is critical that air flow remain strong and constant to keep these units from overheating and damaging internal components.  Internal fans bring air in from the outside, pass it through the projector, usually directed over the sections generating the most heat, and then back out again through a vented panel.  Since standard room air is used in this process, all of the little bits of hair, skin, dirt, and dust that float in room air are also pulled into the projector.  The projector’s air filter prevents these particles from getting inside the optical path and degrading image quality. If it is not regularly cleaned, however, the dust can clog the filter reducing air flow and ultimately damaging the projector.  With repair costs typically starting in the $500.00 range, it is easy to see why keeping the filter clean is so important.

Below is a typical projector.  This unit has a side mounted filter.  Depending on the model, filters will generally be located on the side or the bottom.  The filter cover can be seen as well as the finger tabs that allow for easy removal.

After removing the filter cover, the filter should be exposed.  Again, every model is slightly different so please consult the user’s manual for more specific instructions on removing the filter.  In the following picture, the filter can be seen.  Note the dust in the filter.  The lines are caused by the grill patter on the filter cover.

For this projector, the Hitachi CP-X1250, the filter can be removed separately from the filter cover as shown below.

Once the filter has been removed, it can be cleaned in several ways.  Compressed air can be used to blow the dust out of the filter from the opposite side.  Most filters can also be cleaned with warm water.  If you use water, be sure the filter is dry before putting it back in your projector.  Water and electricity are usually a poor combination.  A clean filter is shown in the next picture.

Reassemble the filter and cover according to the manual.  Many projectors also come with timers that remind you it is time to clean the filter so check the instruction guide to see if your unit has a timer and how to reset the timer if necessesary.

That’s all there is to it.  Clean filters can make a projector last longer and help you get the most life out of the expensive lamps that come in the units.  Dirty filters can lead to many problems including overheating, poor image quality, blown lamps, and degraded optical engines.  The filter cleaning process only takes a few minutes, but it is the single most important maintenance activity an end user can perform on their equipment.  Holt AV recommends checking filters at least once a month and more often in dirty environments like manufacturing plants or places where smoking is common.  Just remember, whatever is in the air will be pulled into a projector so the dirtier the environment, the more often the filter should be checked and cleaned.

One final note on this subject:  Projector technology is constantly changing and some projectors are coming with filters that have longer cleaning cycles or automatically rotate a filter bank to keep clean filters in use.  Although most projectors have user removable filters, many higher end models use more complicated systems that reduce the need for regular cleaning.  Always follow the manufacturer’s recommendations and instructions on filter maintenance.

As always, we welcome questions and if your email is used we will send you a free gift.

This month’s tip concerns a problem that everyone who is called upon to make numerous computer based presentations will eventually come across.  Although it is a simple problem to fix, it can ruin a well crafted PowerPoint slide show.  This problem is the dreaded “Pink Screen” effect.  This can occur at any time during a presentation and, due to Murphy’s Law, often shows up right in the middle of that really crucial sales pitch.  First, we’ll see what this looks like and then discuss what is wrong and how to fix it.

Below is an example of the original output from the computer and what is projected on the screen.

In this image, notice that all of the colors, red, green, and blue, are visible and the image looks normal.  However, when something goes bad the “Pink Screen” can be seen.

Here we see that the image has a pink cast and some areas are too dark to see at all.  This problem can also show up as a blue screen and a yellow screen as shown below.

These types of presentation disasters are often of the result of the same basic problem.  The discolored images are classic examples of what you might see if there is a bad cable connecting a laptop to a projector.  The root cause of the discoloration is a broken wire in the cable (often called the VGA cable) and one of the main colors that make up the images, red, blue and green, is missing.  In the case of the pink screen, the wire carrying the green signal is broken.  With the blue colored image, it is the red signal and in the yellow image it is the blue signal.

Many customers assume that their projector is failing when this kind of discoloration occurs, but more often than not it is just as simple as a bad cable.  The very first thing we as technicians check when we are called to help with a discoloration problem is the cabling.  In the majority of cases, the problem is solved in less than 5 minutes.

For all of you mobile presenters out there, we recommend carrying a spare cable in your projector case.  Cables take a lot of abuse during mobile use and they will fail eventually.  Six foot VGA cables are lightweight, inexpensive and invaluable to both the mobile presenters and conference room technicians.

That’s it for this month’s tech tip.  As always, if you have a technical question about any AV related subject, please email us at techtips@holtav.com.  If your question is chosen for the monthly column we’ll send you a free gift!