Ben.Wilbee Posted September 21, 2014 Share Posted September 21, 2014 Hi, At a venue I'm looking after we have an old DTS Moonlight 575 follow spot, I recently replaced the bulb and the light has developed quite a flicker since the new bulb went in. The flicker seems to get worse the longer the fixture is on. Is this likely to be a faulty bulb or is it a problem with the ballast? Cheers, Ben Link to comment Share on other sites More sharing options...
Jivemaster Posted September 21, 2014 Share Posted September 21, 2014 Look also at the lamp holder. A burned contact in the holder can destroy the next lamp quickly. Do you still have the old lamp? Can you see burn marks where the terminals actually touch the pins. If so get a correct new holder asap. Usually this is caused by the lamp getting too hot in the lantern and the contact springs softening until they lose their grip. Check that the air vents/fan are as they should be, a damp cloth will sometimes remove the dust. Link to comment Share on other sites More sharing options...
Ben.Wilbee Posted September 21, 2014 Author Share Posted September 21, 2014 Look also at the lamp holder. A burned contact in the holder can destroy the next lamp quickly. Do you still have the old lamp? Can you see burn marks where the terminals actually touch the pins. If so get a correct new holder asap. Usually this is caused by the lamp getting too hot in the lantern and the contact springs softening until they lose their grip. Check that the air vents/fan are as they should be, a damp cloth will sometimes remove the dust. Thanks for the reply, I had a good look earlier, the lamp is a discharge lamp with screw connectors which are well tightened so that connection's not the issue... although it's dusty in certain areas it's not overly so and there is a good air flow through the fixture. It does seem to be fine for a good 20 minuets before the flicker starts so heat could be a factor still. It's a very old looking non digital ballast if this would make a difference? Link to comment Share on other sites More sharing options...
bigclive Posted September 21, 2014 Share Posted September 21, 2014 Is the flicker manifesting itself as a distinct wavering of the light? It sounds like it could be an unstable arc in the lamp. It may settle down if you leave it running for a good length of time, but if it doesn't then talk to your lamp supplier with a view to getting a replacement. Link to comment Share on other sites More sharing options...
Don Allen Posted September 21, 2014 Share Posted September 21, 2014 Is the minuet an English unit of time left over from the days of candlelight ? (it seems a slow dance to me ?) Link to comment Share on other sites More sharing options...
DrV Posted September 22, 2014 Share Posted September 22, 2014 I don't know this particular fixture but some large discharge fixtures have a magnet or magnets near the lamp to stabilise the arc. Has this been accidentally removed or turned round during replacement?Dave E2A: Just looked and it uses an HMI575 so this won't be relevant Link to comment Share on other sites More sharing options...
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