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Topic: Difference between bulb voltages.
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted May 23, 2005 01:29 PM
You're absolutely right, Rick.
I've been down a similar road with regard to 120 volt vs. 240 volt lamps for my Elmo E-80 (see much earlier posts).
This particular projector's handbook stated that you could use up to a 750 watt lamp at 120 volts, but only a 500 watt lamp at 240 volts. As there is no lamp transformer in this machine, current could not be, and was not the issue.
NOTE: Although in the UK, our home is wired for both 240 and 120 volts, so I can use either.
To cut a long story short, it turned out that the 120 volt, 750 watt bulb had a much more concentrated filament arrangement, whereas a 750 watt, 240 volt bulb had its filament spread over a much wider area.
A 500 watt, 240 volt lamp had exactly the same filament configuration as the 750 watt, 120 volt lamp.
It then followed that the condenser lens in the projector couldn't pick up and focus all the light from the 750 watt, 240 volt lamp, whereas it could for all the others.
Moral of the story: when trying a different lamp, examine the filament configuration. It must be the same as the OEM for max. brilliance on the screen!
Good luck!
Dave.
-------------------- Dave.
Valves and celluloid - a great combination! Early technology rules OK!
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