Are all MH bulbs the same voltage. I mean do all the ballasts put the same voltage to the bulb? I'm looking at replacing a projector's dead bulb and understand matching the wattage, but am unsure of the voltage question.
I would use an exact replacement if you can find the spec's.
I work a lot with Metal Halide bulbs in my other hobby, Reef Tank Aquariums, and often a particular type of bulb has to be matched *exactly* to a type of ballast. Starting voltage, open circuit voltage, can all be different. Different wattage of bulbs have different voltages.
However, it's possible that projector bulbs are all the same kind but my gut feeling is that they are not.
So just measuring open circuit voltage wont be a good idea? Do you think that projector manufacurers just buy the ballasts from a supplier or make them themselves? I guess I'll have to look for some markings on the ballast itself now to do a cross reference.....or is it just in my best interests to replace the ballast and bulb myself instead of looking for a replacement bulb that might not be easy to get the specs of
apparently if you look closely on the bulb there is supposed to be numbers and if you get these markings you can do a search on that particular bulb
also i find that all these cheaper metal halide bulbs seen to be very large i have never seen a metal halide for sale on the net as small as the projector bulb type but look here http://www.bltdirect.co.uk/cat71_1.htm
for same wattage and double ended also 20000 hours life these could possibly fit into commercial projectors
thanx but i dont see any markings on the bulb so i will never know what type or voltage it is all i know is that it is 150 watt and is metal halide also it is held in a chalky white type of substance in the base of the parabolic reflector