Beaulieu 708 lamp conversion ?

[Steve Lee]

For some time now I have thought about changing the lamp in my Beaulieu 708 projector, over to something that delivers a punch. I have always thought for such a large super 8 projector, the light output is pretty pitiful.
You look at this machine and think you're going to need protective eyewear to shield you from the blazing light, alas this is not the case in reality.
I know that there are two option for this, but the question is which road do I go down?
Fortunately being a large machine there is plenty of room inside to install whatever is needed. Even if it means removing one of the speakers to do so. As I would like to keep it self contained if possible within the unit.

First option is to install a higher wattage lamp, that will require a transformer, lamp holder and 250w lamp. Similar to the conversion that Paul Adsett has done to his GS1200.
The projector's control switch could be rewired to activate the new transformer. The transformer could be mounted inside on the back cover, so no other modification would be needed.
The problem is I don't know what that extra 100 watts will gain on the screen, as these lamps all seem to have an output of 800 lumens.

Option two a 150w HID. I know that there is a little more work involved here, The lamphouse on these machines is quite large, so there is plenty of room to fit a dowser with a solenoid, this could be fired by again using the projector's control switch. So when you turn the projector over to project, this lifts the dowser out of the way.
The one thing I am trying to find out is, just how much airflow is needed for these lamps when the projector is in standstill mode. Also does the air have to be pushed or pulled from the lamp. I have been trying to find out this information, but there is nothing wirtten up about this. Just the same copy and paste details from everyone selling them.
I would prefer not to have to cut a hole in the lamphouse door to install a fan, but if needs be, so be it.
If anyone has a projector that has been converted to HID could you help answer my questions as I would be grateful to know.

Steve

[Paul Adsett]

Can't speak for HID Steve, but here is what I have found using the 250W ELC lamp in the GS1200. First, there is a considerable improvement in light output as compared with the OEM 200w ESC lamp, even more so compared to the dim 200W ELJ lamp. Crude measurements with a light meter shows a doubling of light on the screen. It is a very apparent change in visual impact. The GS can handle the increased heat load without difficulty and remember that all lamp electrical and thermal load is now removed from the projectors transformer which is now just coasting along with low power level circuitry and motors to drive. So this offers the additional potential benefit of greatly improving the life of your projector. On the GS1200 Thomas and Graham advise moving the lamp position further back from the gate by an additional 10mm. I do the same and IMO the ELC lamp in this position provides excellent uniformity of illumination.
I would imagine that 250w ELC conversion of the Beaulieu 708, with its large lamp house, would be very straight forward and , as in the case of the GS1200, you might not need any additional forced air flow.
Here is a pic of the external power supply that I made for my GS1200'S It works great and there is no way I would go back to the 200w lamp:

[John Burgess]

Hi Steve, if it’s any help I have converted both an Elf RM1 and a Kodak sound 8 to hid. The Elf blows air in to the lamp house, the Kodak pulls air from inside, so two different cooling methods,remember HID lamps are only drawing 1.5 amps to achieve this extremely white light, it’s the colour temp of the light that achieves this.. Both machines have performed faultless and have had lots of use . So either form of cooling would be fine.
Good luck with your conversion
. John

[Steve Lee]

Thank you Paul and John for your replies it's much appreciate.

My thoughts were, as long as there is a continuous airflow through the lamp house from the moment the machine is powered up, this should be fine for the 150w HID lamp.
After studying the service manual and circuit diagram for this machine it looks like it could be an easy conversion job. Unlike the gs1200 there is plenty of room inside and everything is accessible without having to remove anything.

On top of the main transformer there are 4 threaded mounting holes, it could be possible to fix a bracket to these to hold the new lamp ballast and 12v dc transformer, as there is plenty of room to do so.




In the back of the projector there is a fan pipe that connects the main motor's fan to a vent on the back cover. I will 3d print a new one so it is possible to install a 12v turbo fan to push air into the lamphouse even when the projector is not running.



On top of the lamphouse door, the vents are removable. I will replace them with a piece of aluminium with a large hole cut out, so it is possible to fit another 50mm 12v fan, for the air extraction. This would save cutting a hole in the actual door.



Within the lamp house compartment there is plenty of room to fit a small 12v solenoid for the dowser, which I will also make out of aluminum, so it works on a spring loaded pivot.

John, any idea what the distance should be between the front of the lamp and the back of the aperture plate. As this would be helpful to know before I start drilling holes in the machine.
Many thanks
Steve