HMI Striking Issues (Shoot Tomorrow!)

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drcheese

Well-known member
I recently added a 1200w HMI Sirio Fresnel and LTM 575/1200w Electronic Ballast to my light kit. Recently as in I paid for it two weeks ago, shipping got delayed, it showed up a couple hours ago and I have a shoot tomorrow.

And as you might have guessed from the subject line of this post, it didn't produce any light.

I have limited HMI experience, but here's what I know:
- When all connected and plugged in, the ballast lights up when turned on and when I hit ignite the fans start in the ballast.
- When all connected and I press ignite from the head the fans on the ballast also turn on and the green light on the head's ignite button goes on (though dimly, but I think that's just the bulb they use there).
- The bulb itself was said to be new, though I assumed it was tested. When I took it out of its package it stuck a little to the plastic (maybe nothing) and I noticed there were little specks in the main sphere of the bulb (probably also nothing?)
- I inserted the bulb nipple out and tightened it down (never once touching the quartz). I did notice that the mount for the bulb isn't firmly mounted, as in it rattles a bit. Not sure if that matters.


And now I'm going to admit something very stupid... I wanted to check the connections on the bulb to see if they were tight, so I opened up the fresnel and went to touch the metal.... whilst forgetting that the ballast was still on. Got a little bit of a buzz. Not very much, but I guess from this I know that some electricity is going to the bulb. And yes, I will be smarter in the future about that.

So can anyone out there please offer any suggestions? Is this a burnt out bulb? Can I do anything else to test for this? I messaged the eBay seller, but they're a business down in LA and won't be back until Monday.

Thanks for any and all help!
 
If the I understand correctly, the connection between the bulbs electrodes (end) and vacuum (glass) may be loose? if this is correct your bulb has probably been damaged.
 
Sorry, I explained poorly. The bulb itself is solid (metal and glass are connected fine), the U-brackets inside the HMI head connect to the bulb solidly, but the U-brackets connection to the rest of the head is a little loose.

I was poking around some more, and I was thinking that if electricity is getting to the bulb, but the bulb isn't lighting, then maybe that initial burst to get the bulb to arc isn't happening. Or it isn't getting enough power or when it's trying to arc some other metal is to close and interfering with the arc.

Although I'm not sure what to do about any of that, and if the unit was tested before it was shipped then I don't know why it would happen this way now.
 
drcheese said:
I have limited HMI experience, but here's what I know:

- When all connected and I press ignite from the head the fans on the ballast also turn on and the green light on the head's ignite button goes on (though dimly, but I think that's just the bulb they use there).!
Click to expand...

There are several possible reasons why your head is not firing. Based upon this observation it may be as simple as the "safety loop" is not complete. From your description is sounds as if the ballast is never attempting a strike which eliminates the bulb as a potential problem. Electronic ballast go through a series of self diagnostic's before attempting a strike. One of the first things that it checks for is that the lens is in tact and the lens door is closed. It does this by sending current through a safety loop circuit. If the circuit is interrupted the ballast does not attempt the strike. If after hitting the ignite button you hear several clicks but no arc sound, it is because the ballast is shutting itself down. The safety switch is closed by a mechanical relay from the lens door. There is usually some type of plunger that is depressed by the lens when the door is closed. It is possible that the mechanical relay needs adjustment so that it closes the switch or that it was damaged in shipping. The way to tell is to hold your hear very close to the head as you slowly close the door. Besides the sound of the door latch you should be able to hear the safety switch close. If you hear nothing then it requires adjustment or repair. It is not recommended, but in a pinch you can jumper over the switch to complete the safety circuit.

drcheese said:
I recently added a 1200w HMI Sirio Fresnel and LTM 575/1200w Electronic Ballast to my light kit. !
Click to expand...

If after confirming that the safety switch is closing you still do not get a striking sound. The second possibility has to do with the fact that the head and ballasts are made by different manufacturers. My first question to you is: were you sold the light and ballast as a complete system or did you buy them in separate auctions. Second, LTM never made an electronic ballast themselves but either sold the Lightmaker or Power Gems ballasts under their name. Do you know which of these two is the manufacturer of your ballast. I will guess it was made by Lightmaker. This is an important consideration because not all electronic ballasts are compatible with all heads. While the head cable may connect, the "pin out" or the assignment of the functions of each pin varies slightly from head manufacturer to head manufacturer. This is a distinct possibility given that the ballast was manufactured for a different head than the one you are using it with. For instance the start circuit might we switched with the safety loop. The faint glow to the start light seem to indicate as much. If this is the case, you may only have to swap some pins around on the ballast connector to make it work. But you first have to know how the head is wired. I would suggest you go online and see if you can't get the wiring schematics for both the head and ballast so that you can determine what needs to be where. Good Luck.

Guy Holt, Gaffer, SreenLight & Grip, Boston[/QUOTE]
 
Thank you for the response!

The ballast is a Lightmaker brand, and the head and the ballast were sold as a set. They were apparently used together for many years as a "workhorse" and according to the seller (maccam in LA) everything was tested and working when it left. They also sold an identical system a few months back and according to eBay he seemed happy with the purchase.

One note to make, the ballast doesn't turn on and then turn off when I ignite. The ballast turns on (makes two clicks after I ignite) and stays whirring until I either turn it off at the head or turn off the power at the ballast. I'm guessing it's bad to let it keep running like this if the light isn't going on?

I ran a test on the safety switch and I think it's working. Basically while the ballast was whirring I opened the door to the head, and the ballast immediately turned off (stopped whirring). Does that sound right?

Thanks again!
 
drcheese said:
One note to make, the ballast doesn't turn on and then turn off when I ignite. The ballast turns on (makes two clicks after I ignite) and stays whirring until I either turn it off at the head or turn off the power at the ballast. I'm guessing it's bad to let it keep running like this if the light isn't going on?

I ran a test on the safety switch and I think it's working. Basically while the ballast was whirring I opened the door to the head, and the ballast immediately turned off (stopped whirring). Does that sound right?
Click to expand...

These were not the answers I wanted to hear for your sake. Maccam is a very reputable outfit and if anyone knows how to match the pin out of a Lightmaker ballast to a head it is Michael MacDonald at Maccam TV. That the ballast shuts off when you open the lens door confirms that the safety switch is closed when the door is closed. The fact that the ballast is still not attempting a strike, even after going through its self diagnostics, indicates the problem is in the wiring and not related to the bulb. The next possibility is a poor conductor in the head cable. The first thing to do is swap out the head cable for another if you have one. If not check continuity between the female and male pins for each conductor of the cable to see if there is a break in one of them. If there is, that is your problem. Most HMI head cables have seven conductors but the systems usually only use six of them for a specific wattage. That is the VOH for a 1200 head will be a separate conductor from the VOH for a 575 head. It is not uncommon for the VOH of the 1200 conductor to burn out in time. If you can find the wiring schematics on line and determine which one is used for a 575, you can swap it around in the cable connectors for the burned out 1200 VOH conductor. After swaping the pins, that head cable will only be good for 1200 heads and will not work with 575s.

Good Luck.

Guy Holt, Gaffer, SreenLight & Grip, Boston[/QUOTE][/QUOTE]
 
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Unfortunately the head cable is permanently affixed to the head for this model, so I can't switch it out. I don't see any break in the pins (they all look solid?), but I really don't know what I'm looking for. I can't seem to find any schematics online either.

Thanks for all the help and suggestions. I think I might do more damage than good if I tried to open the ballast up and I've got to load up for the shoot now anyway. It sucks that the shipping got delayed and I couldn't have received it on a weekday. I'll call Maccam tomorrow tell them what's up, and then maybe bring it by a local rental house to see if they'll help me debug the problem. Hopefully this all gets resolved quickly and cheaply, but I'll post back here when I find out the solution for sure.
 
In case anyone stumbles upon this thread with a similar problem in the future I thought I'd post the resolution.

I ended up sending the light/ballast back to maccam (who paid for shipping), they traced the problem back to the ballast and had it repaired. They said that there was "some minor circuitry failures" in it, partly because it's an older ballast. It arrived yesterday and the light worked.

So there you go. Ballast. Not sure exactly what happened, or if it will happen again, but I'm guessing with the older electronic ballasts that they need to be handled with extreme care, and FedEx did not do that. I just hope these problems don't happen too often. I also learned that Lightmaker's ballast schematics are confidential, so I won't be able to tinker with this myself if it goes down.
 
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