Re: Projector temperature

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

John Fairstein's posting encouraged me to measure the temperature in 
my TDC 116 projector.  I used a home digital thermometer with an
outdoors sensor.  My TDC has 750W bulbs.  I found that there is a
temperature variation depending on what you have in the slide carrier:

Condition                   deg F       deg C
---------------------      -------     -------
Plain Glass                   98          37
RBT mounted slide            101          38
Glass mounted slide          103          39
No slide in carrier          110          43
No carrier in place          125          52
Heat filters removed        >160         >71

In all cases the sensor was placed in front of the slide.  The accuracy
in the temperature measurement is a few degrees F.

Here is how I explain these variations:  There is a current of air from 
the cooling fan going towards the slide.  With the carrier and a slide 
in place the air is forced to the sides with a greater velocity.  
Without the carrier the velocity of the air is lower and that causes the 
temperature in the gate to rise.  With the temperature of the human body 
roughly 100F, 110F is a very cool temperature.  All slides (even RBT with 
black side towards the lamps) did not even feel warm at touch.

Now, here is the exciting part!  I removed the heat filters to see what 
effect this has on the temperature.  Without any carrier in place, the 
temperature in the gate quickly exceeded 160F which is the limit of my 
sensor.  With a carrier and glass in place, the temperature also rose 
above 160F.  And the fun part: I put an RBT mount with the white side 
towards the lamps.  As I was looking at the temperature rising above 160F 
at about 20 seconds I smelled something burning.  I quickly removed the 
slide and, sure enough, the RBT mount was melting!!!  This was a slide 
with Jon Golden, Dr. T and other celebrities visiting Paul Wing in a 
hospital in Boston.  The black side was melting even though it was not 
facing the lamps.  The white part was OK.  Now I need to remount it!

Conclusion:  If your projector fan and heat filters (especially heat 
filters) are working OK then you have nothing to fear and even with 750W 
bulbs in the TDC projector the temperature is a cool 110F.  Without heat 
filters you are in big trouble!  The heat filters absorb a great amount
of heat.  After the fan was running for a minute, everything felt cool
and I attempted to remove the heat filters.  I got a nasty burn when I
touched them.  They are HOT!!!

It would be nice to see similar data for other projectors and bulb 
wattage.

Reporting from Cleveland OH -- George Themelis


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