Bulb won't fire

[Big Country]

I run the Sunlight Supply 250w Bluewave M80 HQI ballasts for my MH's. Just replaced the bulbs and one of my fixtures will not fire a brand new Radium 20K, they are working fine in all the other identical fixtures. It's not the bulb, I installed it in another reflector and it fired right up. I put a old XM 10K bulb into the fixture and it fires right up.

Every time I put a new or used Radium in the one fixture it won't fire, always worked before. Why would it fire a XM 10K but not a Radium 20K?

[Coral Hind]

With the power off try pulling the center post contact out some, it might not be making proper contact. Different bulb base shapes can cause miss fires when changing bulb types.

 

The ballast capacitor/ignitor might be getting weak and needs to be replaced.

[Coral Hind]

Were you able to figure out anything?

[Big Country]

Haven't had time to try yet, just need to figure out which cord going into the ballast controls this fixture so I don't fry myself...lol. Sounds like it may work, the XM's have a longer nipple on the bottom so it very well could have pushed the center piece in on that on if I screwed the light in a little much

[Big Country]

Well, I cleaned the nipple of the new Radium Bulb, removed the XM bulb and pulled on the center contact in the socket with a pair of needlenose, after unplugging from ballast of course...lol. Installed the Radium and it still didn't fire when the lights came on. I know the bulb is good since I put it in a different fixture and it works fine. I'm going to try and swap radiums into different fixtures since this pendant doesn't want to fire this bulb. I'm just out of ideas.

[bravanc]

Did you check the wires connecting to the socket? They could be burnt, corroded, or loose.

[Coral Hind]

Can you swap the ballasts around to use a different socket to try to rule out any socket issue? It sounds like the starting circuit of the ballast has gotten weak.

[Big Country]

Did you check the wires connecting to the socket? They could be burnt, corroded, or loose.

 

Yes, first thing I checked since I had one of the wires in another fixture come out of the crimp awhile back.

 

Can you swap the ballasts around to use a different socket to try to rule out any socket issue? It sounds like the starting circuit of the ballast has gotten weak.

 

I hadn't tried that, I did plug the fixture into another socket on my ballast and it fired. You are probably right that something has gotten weak on that ballast but the reality is that I just don't know what to check, or how to check it.