Gaffer question...old HMI unit resistance check/fix?

[Ron Michaels]

Hey guys,
i have an old 1200w HMI (w/ mag ballast) unit that takes double ended globes. I purchased 2 Osram 1200w bulbs that are rated at 6000k (plus or minus). However I am getting about 5300k to 5400k readings at best from the light. Now I know old fixtures can decrease output to the bulb, due to corrosion and loose wiring and such. Could anyone give me some tips and tricks on checking resistance and what to look for? Obviously im not an electrician but I have a little bit of experience checking equipment with a multimeter.
Thanks,
Ron

 

[Chris McKechnie]

You're allowing plenty of time...like 10-15 minutes for the lamp to come up to full temp (since it's a mag ballast) right? Mag ballasts are a lot slower in getting temp consistency, so make sure you're waiting about that long before getting readings (which I assume you are).

Your issue could be caused by either the ballast or the lamp head itself. While mag ballasts are a lot easier to work on/troubleshoot than an electronic ballast, I'd still get it serviced by a lighting shop. You could do some basic cleaning/inspecting the connections, but anything outside of that and you could do more harm than good.