Believe your
LCL is 6.1/2" (Lamp Center Length - at Bot of
Ceramic Base - Where Pins Come Out, to the center of the
filament.) This is based off the 1500T24/6 specifications.
Assuming the wiring and
fixture is in good condition, most modern
halogen lamps CYV, CXZ, or CYX are a 5"
LCL for lamp center direct replacement. Done this with a c.1948 Century #1560 in mounting a CYV to it for rental that was displaying old guitars and wanted old lights for it also. 1.5" difference between the modern
halogen replacement lamp and the lamp replaced.
Now how can anyone ever overcome this problem of 1.5" in difference between
LCL and where you need to be? Took a few hours and some spacer plates plus some longer screws
etc. in changing hardware out some - much of the time was spent on
bench focus in fact. My crew loved the work in modifying and bench focusing the above and a 3Kw Kliegl Dyna Beam for the same show that needed lamps as it were lamped down or at least lamps that could be replaced. Was fun and engineering for them, but also in the case of the Century #1560, something that was also a really unsafe
fixture to be bench focusing - exposed terminals and all. Kept all of us on our toes as they adjusted for
bench focus the new lamps in modified seat heights given tools in near proximity to live terminals. This with me as per an “expert” but never really worked with them standing over my skilled electricians as they did their work so as to ensure they as it were didn’t loose focus.
See you have a volunteer theater/staff. Assume you will not be there the night even an upgraded
fixture needs a replacement lamp. Can be done with
power down and kids/vounteer staff do all kids of stuff in a responsible way, but all kinds of cautions even after any such upgrade to fit a new lamp to an old
fixture of this type in lamp changing. You need the fixtures is respected, and no doubt on replacement list, can be upgraded but the caution on installing further lamps.