Acme spot knight moving head 250w elc keeps blowing bulbs?

[bigmrg]

Hi every one, hope this finds you well, I have a couple of old Acme spot knight (knight spot? Can't remember) moving heads with 250w 24v etc dichroic bulbs in. The pair have had the same bulbs for the past 5 years but one has started blowing bulbs after about 20 minutes.

I'm using proper 500+ hour osrams or ge and I stripped the head down to make sure it was cooling ok.

I'm going to change the lamp holder although it feels tight. Maybe it moves and the arcing blows the bulb?

other than that, does anyone know of any other reason it could be blowing the bulbs? Its installed in a club full time.

Finally, the filament appears to remain intact but nothing else cracks which seems odd. I've had dichroics split at the Base rather than the filament break.

Many thanks in advance.

[Brian]

I'm going to change the lamp holder...

 

As I read the topic title that was my first thought.

 

Do you have a failed lamp to hand? Have you examined the pins and compared them to a new lamp?

[KevinE]

if its not the lampholder then the wiring loom that supplies it might also be a suspect, causing it to cut in/out as it makes/breaks. Worn looms are particularly common in club lighting due to the manic movements!

[Chris Beesley]

We have lamp holders/looms on the shelf at Prolight for these. Drop me a mail to chris@prolight.co.uk if you need any assistance.

[Jivemaster]

If the lamp capsule or reflector is distorted or discoloured then it's a cooling problem. If not it's burned contacts.

[emsgeorge]

And ELC lamps are generally quite short life. some as little as 90 hours.

 

There is a 300hr version available I believe.

 

I used to spend most of my week changing these damn lamps out in various fixtures in various clubs around Brighton.