Exploding lamps

[Shaun]

A few minutes before the end of my gig at the weekend and I heard a bang. Checked my moving head and the light was out, and shards of glass all around it. Is it common for disharge lamps to explode?

[DJ James Lake]

When they go yes they can explode and with a lot of noise. I had one go in a VR8 a couple of years ago and it scared the living daylights out of me.

I think mine was due to condensation at the time.

[DJ Jules]

Yup, they can go bang - as they get older deposits build up on the inside of the glass which hold the heat, causing hot spots on the glass. The same thing happens if you happen to get grease or condensation on the outside of the lamp.

I had one fail like this inside a DLP projector and it destroyed the colour wheel (unfortunately completely uneconomical to repair).

Julian

[Shaun]

I've yet to open up the fixture. Planning on doing that tomorrow so hopefully no damage.

I'd noticed a flickering on the lamp output over the last few weeks or so....I should have changed them sooner. I didn't realise they could go bang like that. Almost messed my pants!

[Jiggles]

Yup! Just they way they go. If you got all the heads at the same time replace them all at once so all the light output is the same. Its highly unlikely for there to be damage in the fixture. Quick hoover and inspect pop in a new lamp and you are good to go. Next time keep an eye on the number of hours the lamps been through and it would mean you won't go though all this again.

[Larry B Entertainment]

Never seen a discharge lamp go up but I have seen par 64 lamps explode. No wonder there is safety mesh in there to catch the glass.

[stormproductions]

Thankfully I've only had 1 discharge lamp blow on me but the unit was on test on the bench at the time so I was quite close and it does make you jump. They can easliy damage reflectors, UV filters etc inside so that's why the manufacturers say to change them according to lamp life. I realise of course that not all units have lamp hour meters, but you can easily tell looking at the lamp if it's an old one or not.

I try to run decent condition lamps in all our units but of course some of the less important kit has older lamps as it would cost me thousands to have new lamps in everything and for something that maybe gets used once or twice a year it's really not justifiable.

Do ensure though that you don't touch the outer glass of the lamp at all. A new lamp will have an alcoholic wipe with it which you must use properly when fitting the new lamp. It really does matter!

[Shaun]

I opened up the fixture last night. No damage to functionality but there are pieces of glass shards melted into the plastic casing on the moving heads. The last time I saw anything like that was watching a documentary on Hiroshima 1945. :lol:

[stormproductions]

Yep, that happens, and despite your best cleaning efforts you'll still find fragments appearing for years to come! With the movement of the head they get trapped in the most inconvenient places.

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In the night club I used to work at, they had a 400W UV cannon explode. Luckily, it was only just after we had opened. Wouldn't have liked to see the mess if it was when the club was full!

[katman]

Is it common for disharge lamps to explode?

Very common. Its one of the reasons some video projectors wont power up once the rated lamp life is reached. Running beyond that time greatly increases the risk of catastrophic lamp failure and resulting damage. By the time a lamp has reached the rated life its light output will also be pathetic to that of a new lamp.

Having said that, playing by the rules doesnt mean a lamp will not explode anyway as I found out when I had a 5 grand video projector written off by lamp failure :(