Arri 650w Fresnel
 

I bought one of these last week and just used it on a gig. I noticed that when focusing the light it will reach a certain point and the light will go off. As I continue to turn it will come back on....seems to be hit or miss when it goes of or comes on, but it seems to happen in the middle of the focus range. I don't think this is normal. but does it sound like anything anyone has seen before. This is my first Arri so excuse me if this is normal operation.

No, That is not normal.

Check that the lamp is seated properly (unplug power first!!) in the ceramic base.
Also have a look for any wires that are catching when moving the focus.

John: I've seen that happen on Ianiro focusable open face instruments and Rohan is right, it's not normal. Very likely a loose connection (which is of course potentially quite dangerous).

John,

Also, if you're not familiar working with hot lights like this - remember you should NEVER EVER EVER touch a bare bulb surface with your fingers - even when it's stone cold.

The oils from your fingertips can cause uneven bulb surface heating and cooling and lead to bulb explosion. (Showing talent with hot glass fragments is NEVER recommended in the practice of videotaping.)

Always use an appropriate layer of paper or tissue or foam as a buffer between fingers and lamp surface from the moment it comes out of the box until it's properly seated in the fixture.

If you already knew this sorry to belabor the point - but someone else reading here might not.

(you may now resume you're regular site perusal...)

Thanks Bill..but yeah I was aware of that..I have some Lowel lights that I've used for a while. This was my first fresnel though, and was not sure of whether that behavior was normal when focusing it. I'm going to return this one Monday.

Most likely the wire(s) from the terminal block to the lampholder is broken or lose. This is common on Fresnels as the two wires move anytime the focus knob moves.

See for parts:

http://www.arri.de/fileadmin/media/a...pare_parts.pdf

If you are handy with tools you can fix it yourself. Make sure that the set screws that hold the wire connectors in place are tight first, if nothing moves then replace the two wires. Caution, these are heat resistant and not ordinary wires, get the replacements from Arri.

If you are tool challenged send it out to be fixed. If the wire comes out and touches the other terminal is 4th of July.