Determining if an HMI globe is shot.

Phil Gerke · April 18, 2007

Hi all,

I have little knowledge in the realm of HMI lighting and I am trying to figure out if the globe in my Joker 800 is toast or if it is something in the ballast. My gut is that it is the globe, even though it is relatively low hours. However it is a rental and though I know most of the renters it is possible that something happened. Basically it just won't re-strike, the ballast seems to be doing its job, the globe is just not taking it. I really don't know what to look for in a bad HMI globe. Can anyone help me out? I could probably post a photo if need be.

Couple other things, the light was purchased in September of 06, 300 hours at most. I did get it back from a rental once and it was damp, though I dried it out well and it worked fine.

K5600 has a pretty good rep, I really don't think its the ballast.

Any info would be great, thanks a lot!

Phil

edward read · April 18, 2007

Hey,

so, do you here the ignition pulse when you hit the on button? Its the "shorted wire sound" right before the lamp goes on. If not then its either the lamp safety switch circuit or the ballast or the ignitor.

Other things to check:

re plug the ballast and head cable. With the lamp off, and with a pair of gloves check and make sure that the lamp is seated properly in its holder and that the connections are not carbonized (all black). DO NOT touch the glass of the lamp. If its a rental then bring the whole thing back and have it replaced. They will swap pieces until they can isolate the problem.

My bet is its the ballast. HMI lamps in general, unless the glass envelope is broken or puntured, usually don't just die. They get really crappy in color as they age but they are usually good for 4 or 500 hours. Some can be rated for 750.

Again, you said its a rental, just have it replaced. This is the safest thing to do.

Phil Gerke · April 19, 2007

Hey,

so, do you here the ignition pulse when you hit the on button? Its the "shorted wire sound" right before the lamp goes on. If not then its either the lamp safety switch circuit or the ballast or the ignitor.

Other things to check:

re plug the ballast and head cable. With the lamp off, and with a pair of gloves check and make sure that the lamp is seated properly in its holder and that the connections are not carbonized (all black). DO NOT touch the glass of the lamp. If its a rental then bring the whole thing back and have it replaced. They will swap pieces until they can isolate the problem.

My bet is its the ballast. HMI lamps in general, unless the glass envelope is broken or puntured, usually don't just die. They get really crappy in color as they age but they are usually good for 4 or 500 hours. Some can be rated for 750.

Again, you said its a rental, just have it replaced. This is the safest thing to do.

Thanks a lot for the advise. I will check the things you mentioned. However I am hearing the ignition pulse, but no strike.

I should have been more specific, its our rental, meaning we rent it out to locals and such.

As far as I can tell the bulb is not puntured or anything, I'll pull it and check the contacts. I did not know about the color shifting as it gets older, and from what you said now I am wondering if it is not the ballast.

Ok, more investigation.

Thanks!

Richard Andrewski · April 19, 2007

The most effective debugging technique is to systematically start with the simple things and work towards the more complex. This would go like: cabling, connections, bulb then ballast last. I think you either have a bad connection somewhere or a bad bulb. I wonder why you don't have a spare bulb around? If you're a rental house you're going to have to deal with that sooner or later and yes you only have about 200 hours left on that bulb unless it's meeting an early demise.

The simplest would be to swap in a new bulb and try it if you want to do all this yourself. Can a bad ballast ruin a good bulb? It's possible but doesn't happen often and it's a risk you have to take when you decide to debug yourself. Otherwise you'll have to take it in and have someone determine if it's a ballast problem or not ultimately without another bulb to try out.

edward read · April 19, 2007

Andrew is entirely correct. Switching out for known good lamps, and or ballasts is the way to isolate the problem.

Let us know what you find. Once you rule out the headcable then I would think its a ballast.

timHealy · April 19, 2007

Assuming all the equipment looks physically good, when having trouble with HMI's I typically

1: check voltage with a meter

2: check micro switch - make sure it is depressed

3: swap header cables or pull a piece of header out of line if using two

4: try swapping the ballast

5: try swapping the head

3,4,5 can be switched. Typically do whatever is easiest first depending on how the light is rigged. For example if a light is in a ceiling and the cable is tied up in too many places then swap ballasts first.

As far as the bulb is concerned. check to see it physically looks good, no broken glass or broken porcelain ends. A normal bulb the glass would look clean with some balls of what looks like mercury floating around the center. Anything other than that like yellowing or very black colorations then perhaps it is just the bulb. Also if the bulb does strike but takes a long time to warm up or is very green or magenta, I would use a new bulb.

as always just my 2 cents

good luck

best

Tim

Edited April 19, 2007 by timHealy

Phil Gerke · April 20, 2007

Well I have done as much diagnostic work that I am comfortable doing, which sad to say is not much. I followed much of the advice given by you guys. Some things I simply could not do for no other reason than we have the only 800 in town and no means to trouble shoot with another. The decision was made to just send it to K5600 to have them take a look at it, it won't be too big of a deal to not have it around for a while. That being said, I still think its just a spent globe, however I am dissapointed at getting such short life span and this is why I want the ballast looked at, just in case something is up.

I'll report back with details. And yes, we should have an extra bulb for the Joker but we don't, we will though.

Thanks everybody!

Ralph Keyser · April 23, 2007

Phil,

Be sure to let us know what you find out.

It seems like cables have given me the most trouble in HMI rigs, so I'm always curious to hear from others.

Phil Gerke · May 15, 2007

Ok, got our Joker back. First off, K5600 was very quick and easy to work with. I am still unsure what created to problem to begin with, but not only was our bulb toast, but so was the striker. It was still well under warrenty so the striker replacement was no prob, in fact it may have been defective to begin with and may have led to the extremely short life of the bulb. On the other hand the bulb may have been a defect as well and so they replaced it for us.

All in all it was pretty painless, had to rush to get it back for a rental, but it made it fine and works fine. My only gripe was that our barndoors got left behind it seems. Next piece of business is to get a replacement bulb.

Thanks everybody!