LTM 575w metal halide light problem

omnikron

omnikron

Well-known member
I just purchased a used LTM 575w fresnel style metal halide unit used from the marketplace forum here. It was working before the person shipped it to me but I couldn't get it to strike when I received it. I purchased a cheap replacement bulb but it still doesn't strike.

http://www.dvxuser.com/V6/showthread.php?326845-575W-HMI-LTM-w-Electric-Ballast

It's been a while since he's used it and I think I've walked through the process with him and it seems like it should work. I don't want to have to ship this heavy unit back to him and I live far away from anyone that I know that can repair it.


I live 3 hours roundtrip away from the closest grip & lighting place that could repair it and I hate to send it in there if it's something stupid I'm doing wrong or if it's something easy to fix.


The ballast unit has the ability to toggle between 1200w and 575w unit and it has a flicker free switch or a 24p switch and a color temperature dial. I think i have everything set right, and when I turn the ballast unit on, I hear it click and hum, but when I try to strike the light, nothing happens. I replaced the bulb that it came with but still no luck.

Does anyone have experience with these kinds of lights (this is my first time really using one) that may be able to walk me through some troubleshooting steps?

Thanks!
 
Sometimes a small wire might get loose in some of those older lights - happened to me on one ballast.

If i were you i would open the head and the ballast and see that nothing is loose - no wire is broken, if you see something it might be the issue.
 
Nothing happens when you try to strike the light as in, it doesn't even make a flash and static-like noise? Could be a number of things, almost certainly not the lamp though.

Here's a couple basic tests you can perform, you just need to figure out the pinout of the cable. Could be the safety circuit. All HMI's have a switch integrated in the door and if that switch is open, the light won't turn on. You should get continuity between those two pins when the door is closed. It could also be a bad igniter. You should read somewhere around 10 ohms across the two pins for the igniter, if you get no resistance it needs to be replaced. I believe one of the igniter pins will be common with one terminal on the lamp holder, and the safety circuit is whatever two pins aren't either the on/off switch, the ground, or the lamp holder.
 
Thanks everyone. I did open it up and it looked a bit intimidating. The flicker selection switch is broken but the unit appears to be stuck in 24p mode which is fine... And thanks Michael... I missed that part.
 
there should be a micro switch on the front door of the lamp which stops the lamp sparking up if it is open
sometimes it is bent or damaged and will stop the lamp from sparking.
also some ballasts will refuse to spark up if there is no earth or high resistance on the earth at the power supply point.
cheers
 
Man, I'd be careful opening up a ballast… aren't they packed with capacitors and explosives and, like, rabid alligators with ninja throwing stars?? (Sorta kidding - I know a photo power pack can kill you in a heartbeat, vaguely assumed that HMI ballasts are in the same league…)
 
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