Mike O'Regan wrote:
Thanks, Frank.
What problems did you have with the lamps, specifically? Not powerful enough? Not lasting long?
The marc 300 lamps were very unreliable in that some new lamps would strike on the first igniter pulse and run for up to 150/60 hours, but from about 2 to 10 hours most of them developed a white substance inside the glass (mica) envelope, which caused the light output to decrease to well below 50% or less. Some would ignite ok but fail as soon as they were switched off at interval and not ignite for the main feature. Others would develop cracks (devitrification of the mica around the areas where the electrodes entered the envelope) and become black within an hour or two of first installation. Most of them would gradually develop flicker as though they were running on ac instead of dc. The psu was checked for ripple but had a very stable dc output so it was the lamps at fault.
The marc 300 and 350 lamps were very expensive here, and I needed to carry at least twenty new spares because they were so unstable.
Sorry for ranting but I'm still very pissed off with marc 300 lamps, even forty years after getting rid of them and going 100% xenon.