junogoose Posted March 12, 2009 Share Posted March 12, 2009 Is it okay to fit a discharge fixture with a lower-wattage lamp than it is designed for? i.e. - is it okay to 'under-load' a discharge fixture? Given the ballasted nature of these units, I feel that the answer is not obvious. I have two Chauvet Q-Scan250's, which I would like to fit with msd200 lamps to tone down the output for certain applications. I posed the inquiry directly to Chauvet tech 4 days ago and have not received response. -dan Link to comment Share on other sites More sharing options...
Davethsparky Posted March 12, 2009 Share Posted March 12, 2009 The simple answer is no. As you say they have a ballast/control gear which is all designed to work with the specified lamp. I don't know enough to give a full explanation of it all, but my understanding of it is that the ballast is there to control the flow of current through the arc and so control the power dissipated, it wouldn't limit teh current enough for the lower power lamp to function correctly. Hopefully someone else will be along soon to expand on this, or give the right answer if mine proves to be wrong. Link to comment Share on other sites More sharing options...
KevinE Posted March 12, 2009 Share Posted March 12, 2009 No Dave's summed it up well enough as it is! You must ONLY fit the specified lamp or one that is 100% compatible. It is the ballast that determines how much current flows through the lamp, not the lamp. Fit a smaller lamp, and the ballast will drive the same power through it as if it were a big lamp..it isn't intelligent. The lamp will either not strike or will strike and fail, or will damage the fixture. Link to comment Share on other sites More sharing options...
junogoose Posted March 12, 2009 Author Share Posted March 12, 2009 Thanks to both of you. It's exactly what I need to know.My followup question is if it is then ok to swap an MSD250/2 for an MSD250? It would seem logical that they draw the same current regardless of color temp. -dan Link to comment Share on other sites More sharing options...
Davethsparky Posted March 12, 2009 Share Posted March 12, 2009 I can't see it being a problem, checking the specs from phillips they both have the same lamp current (3 amps) so I cant see there being a problem. As you say the only real difference is the colour temperature. Link to comment Share on other sites More sharing options...
csg Posted March 13, 2009 Share Posted March 13, 2009 how about just using a piece of neutral density ( N.D) gel infront of the lens - available in many different stops, this has to be a much more reliable and cheap way of droping the intensity where the fixture does not have a dimmer shutter Link to comment Share on other sites More sharing options...
Joe White Posted March 14, 2009 Share Posted March 14, 2009 The only way to make the output dimmer is a higher wattage lamp as the ballast has the current limited, but warning the color temp will be allot different, So in place off a MSD250/2 put in a 300w version, Tends to be a blue-ish color because of the lower current. Ta Joe Link to comment Share on other sites More sharing options...
Davethsparky Posted March 14, 2009 Share Posted March 14, 2009 The only way to make the output dimmer is a higher wattage lamp as the ballast has the current limited, but warning the color temp will be allot different, So in place off a MSD250/2 put in a 300w version, Tends to be a blue-ish color because of the lower current. Ta Joe Will it maintain the arc reliably of you don't supply enough current? and will it strike ok without putting stress on the ignitor circuitry? Link to comment Share on other sites More sharing options...
Joe Betts Posted March 14, 2009 Share Posted March 14, 2009 Hi Dave, Im no expert on this, but I would imagine it might reduce the life of the ballast atleast to put in a higherwattage bulb, as it will be constantly trying to draw more juice than the ballast can supply. I would imagine it would have a similar effect on the ignitor, and perhaps the bulb too. The only thing I can corrolate to this is, if you put a transformer in the power supply line to a (lets say) Mac 250+which is expecting 240V, and reduce the voltage you are giving it to 200V or 180V, it wont be very happy.I would imagine (but may be wrong) that a similar thing may happen with the arc of this bulb. food for thought....... Link to comment Share on other sites More sharing options...
Davethsparky Posted March 14, 2009 Share Posted March 14, 2009 I'm no expert either but to my mind common sense says it isn't going to do the circuitry/control gear any good. Hopefully someone who does know for sure will be able to clear this up Link to comment Share on other sites More sharing options...
csg Posted March 14, 2009 Share Posted March 14, 2009 Any discharge lamp will try to pull more current than the ballast will allow - that is the whole point of the ballast, which is a current limiting choke which stops the arc current rising past the design limit of the lamp. The suggestion of putting in a larger lamp to reduce output however is a very poor suggestion indeed A larger lamp will have different optical and physical dimentions, a different arc gap (and therefore strike voltage) and voltage requirement, will cost a lot of money, and futher will invalidate any equipment warranty which may be in place Link to comment Share on other sites More sharing options...
Davethsparky Posted March 14, 2009 Share Posted March 14, 2009 Also I don't think its possible to get a 300 watt MSD lamp. I think the next size up is the 575 watt, and the chances of 250 watt control gear striking and maintaining an arc in that seem pretty slim. I would have thought that the best way to reduce light output would be N.D. gel as mentioned previously. Link to comment Share on other sites More sharing options...
smalljoshua Posted March 14, 2009 Share Posted March 14, 2009 You can get a 300w MSD but they are not as readily available as the 250w and 575w versions. Josh Link to comment Share on other sites More sharing options...
Davethsparky Posted March 14, 2009 Share Posted March 14, 2009 I stand corrected, my brief research obviously wasn't enough! Link to comment Share on other sites More sharing options...
Joe White Posted March 15, 2009 Share Posted March 15, 2009 For example some light fixtures I have at the moment they are meant for 70w lamps we currently have 150w ones in , the ballast runs at the same temp as when using 70w lamps. The only end result is the lower output. Joe Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.