750W bulbs in TDC 116?

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

My TDC 116 projector was getting noticeably dimmer and one of the 500W
bulbs blew out last week.  I replaced both bulbs with a pair of new
750W bulbs.  Here are my observations:

- Brightness is increased and I like it!
- Ghosting is definitely increased with the brighter bulbs.
- The projector is getting hotter but the slides are still cool.

I was talking to local 3d enthusiast Jim Motley and he mentioned that
his new 116 projector (acquired for $25 from an old widow) came with
750W bulbs.  The motor was slow but he managed to oil it after he
located the oiling holes looking at the diagram in the "TDC Stereo
Cameras and Projectors Service Instructions" (copy available from 
Reel 3-D, stock #1176, $10 plus shipping).

Jim mentioned that his projector was getting VERY hot using the 750 W
bulbs (to the point that he could smell something burning) and he 
expressed concern about my usage of these bulbs.

Last night we attented a Cleveland Photographic Society special meeting
on stereo photography and I used my TDC to project slides.  Jim told me
that my projector did not appear as hot as his.  After the meeting I 
stopped at his house and we opened both projectors and compared them.

Even though they are both TDC 116 and the serial numbers are close
(a few thousands apart), and they both have the old style carriers
that will show 7p size, my fan motor is different that his.  His
is enclosed in a black case where mine did not have a case.  My
fan was blowing at least twice as much air as his.

>From this I conclude that TDC must have changed fan motors at some
point.  Older projectors might have a stronger fan which will support
the 750 W bulbs, while newer projectors might have a weaker fan that
will not support those bulbs.  

His projector had a third switch, installed by the owner, to run the
fan only.  I have replaced one of the two switches with a 3-way switch
where the middle position will allow you to run the fan with both
bulbs turned off.  I think this is needed when using 750W bulbs. After
the bulbs are turned off, the projector is very hot and some air
is needed to take this heat away and cool the projector down.

The 716 TDC projector appearently has the stonger fan and a 3-way
switch as standard features.

In any case, I am now sold to 750W.  I was happy with my 500W which
were working fine in my 5 foot screen at home but lately I did notice
that they were getting dim.  The 750W will definitely work better
for my larger screen which I plan to use for public presentations.

Regards -- George Themelis


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