Film-Tech Forum ARCHIVE: Hard striking lamps

This is topic Hard striking lamps in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=010718

Posted by Richard May (Member # 2627) on 11-27-2010, 05:55 AM:

This has been an ongoing problem and has gotten very tricky to figure out. Here is the set up. 2 Super Highlight II consoles. Consoles are only 8 years old. Very little use each year. November-December. 7000 watt xenons.

Mostly in the morning when the lamps have cooled, the lamps have a hard time striking. The catch is, when the ignitor "zaps", it doesn't jump across the electrodes. It goes from the base of the cathode up to the ignition wire over the envelope. This was only happening on one machine. These ignitors are the DC version so they quickly pulse the lamps. Eventually they light and all is fine for the day.

Now here is what we have done so far.....First we swapped lamps between the 2 machines. Problem stayed in the same machine. You would think it's the lamphouse then. So then we swapped ignitors. No good. Finally we put an old bulb in and it worked fine. So now it seems the bulb was bad.

Fast forward to this year. We started the year with 2 new lamps as we do every year. We decided to switch from Osrams to ASL (for a number of reasons,the main one being that they advertise their lamps work well at extreme angles). By the 4th or 5th day, the same lamphouse is doing it again. So we start swapping again. We swap the lamps between the 2 machines and now BOTH lamphouses are doing it. So we start over again.

Now I go back to the first machine that start this in the first place. I changed the cable from the ignitor to the lamp cathode. That seemed to work. A week goes by and perfect striking every day. So I decide to change the wire on the other lamphouse. The other morning I did it and now both of them are hard striking again. Go figure.

So I took 2 old lamp and put them in both lamphouses and everything is fine. I spoke to Strong, Osram, and ASL and they all blamed it on the other companies.....as I figured they would.

It really just seems that the newer bulb today suck. The older Osrams worked just fine here. The newer Osrams are the ones that gave us the problems. The ASL's also are giving us the problem. Strong did suggest that the AC ignitors would probably work better because they "really blast the bulb" as they put it.

Btw way, starting volts are around 160VDC and amperage is 165A.

Posted by Louis Bornwasser (Member # 3063) on 11-27-2010, 08:51 AM:

Experimentally, replace the capacitors in the power supply. "Low inrush current" could cause just what you describe and is typical on rarely used equipment. OK after first daily start, right?

Capacitors are thought of as making the dc pure. They are also used to get the bulb lit. They become marginal with disuse.

The 160v is no load, not running voltage, right?

I do not have good data for ASL.. I sell a lot of Osram and have not had this experience with them. Are you buying the "XL" Osram or something lesser? Louis

Posted by Richard May (Member # 2627) on 11-27-2010, 09:19 AM:

Yes, okay after first start 99% of the time. 160VDC no load. I'll replace caps next week.

Posted by Gordon McLeod (Member # 33) on 11-27-2010, 09:39 AM:

I have many locations we just remove the ignition wire

Posted by Richard May (Member # 2627) on 11-27-2010, 10:24 AM:

I have tried that also, but no change.

Posted by Richard May (Member # 2627) on 11-27-2010, 05:43 PM:

Is there anything stopping me from hooking up an AC ignitor in place of the DC one? I have a new ignitor that came from one of the ORC 6000 lamphouses here. Is it a matter of bringing 120VAC to a momentary switch in line with the transformer on the Ignitor?

Posted by Monte L Fullmer (Member # 2797) on 11-27-2010, 09:25 PM:

Ignitors from STRONG (the white DC ones) are good for wanting to fail without notice..

I'd try the AC one since an igniter is an igniter.

Changed the bulb to another one to see if it's the bulb issue?

Posted by Gordon McLeod (Member # 33) on 11-27-2010, 10:20 PM:

if you ca see fly off the ignitor is doing its job
look for the root cause

Posted by Richard May (Member # 2627) on 11-28-2010, 06:41 AM:

I've been looking for the cause. These are 2 brand new bulbs. Also, one of the new bulb last year had the same issue. Like I said, I put an old bulb in and it works fine. So far, 3 out of 4 new bulbs are giving this problem.

Posted by Richard May (Member # 2627) on 12-05-2010, 11:44 AM:

Haven't gotten the caps yet. Even though we are getting more than enough starting volts, the caps can still cause this? Strong has had no answers for us on this problem. The latest is that we took the new bulb out of the master machine and put the one from 2 years ago in and it works fine every time. Now the slave machine with another new bulb is doing the same thing. First stiking in the morning just won't light. It took 10 minutes to get it lit. Again, it does not jump the gap but rather arcs to the ignition wire. Now the rest of the day it will strike immediately every time. I don't get it.

Posted by Tony Bandiera Jr (Member # 2365) on 12-05-2010, 01:12 PM:

Yes Richard, the caps can still cause the problem. The caps store the voltage and help release it as a high CURRENT surge to get the bulb lit. To prove this, you can use a DC clamp-on amp meter With peak hold) on one of the leads from the cap bank. On ignition, you'll see a high-amperage spike (thus the need for a peak-hold meter) then the current will settle down to a fairly steady, low level. With good caps IIRC the "running" amps on the cap bank run around 5-10 amps.

Marginal caps can still store a good no-load voltage, but they won't have enough capacity (pun intended) to supply the necessary current.

Another factor: a lot of new bulbs are, as Joe would say, ass. Bulb manufacturers have been changing the construction and fill gases to either extend life or cut costs, but you are experiencing first hand the results of those changes. I no longer use Osrams of any style due to their poor performance of late. Christies have always proven reliable for me.

Posted by Richard May (Member # 2627) on 12-05-2010, 04:23 PM:

Thanks Tony. I totally agree about the bulbs. The problem is how do I go to the bulb company and say that. Nobody seems to want to take any responsibility. I'll try the new caps when they come in. If that doesn't work, I'll try replacing the DC ignitor with an AC ignitor.

Posted by Jonathan Bodge (Member # 4072) on 12-05-2010, 08:34 PM:

I had this problem and bypassed the zener by striking the bulb as soon as I pressed the automation start. In other words instead of waiting for the voltage to rise to trigger autostrike I just banged it as soon as it was energized. This seemed to work after replacing almost everything. That damn inrush current. Kinda like surf.

Posted by Richard May (Member # 2627) on 12-06-2010, 07:11 AM:

With the DC ignitor, there is no manual strike.

Posted by Tony Bandiera Jr (Member # 2365) on 12-06-2010, 11:51 AM:

That, and Jonathan's advice is very hard on the bulbs, rectifier and ignitors. Trying to strike before the rectifier has built up enough charge is counter-productive and WILL cause more wear on the bulb's electrodes. It also stresses the diode bank (or switching FETs in switchers) as they are now forced to provide the FULL surge of current to get the bulb lit.

Capacitors in rectifers, regardless of type, serve two major purposes: one, to provide the voltage AND CURRENT boost to get the bulb struck, and second to smooth out any remaining AC ripple on the output of the diode bank (or from the switching FETs.)

I do not recommend Jonathan's method unless you feel like replacing ignitors and diodes/switchers on a regular basis.

Posted by Richard May (Member # 2627) on 12-06-2010, 07:26 PM:

So while I am impatiently waiting for the caps to arrive, I am going to try the AC ignitor that we have here. I'm going to hook up a momentary switch to supply 110VAC to the transformer on the ignitor assembly. Does it matter which terminals the DC leads go to on the HV coil?

Posted by Jonathan Bodge (Member # 4072) on 12-06-2010, 08:16 PM:

What was weird about this install was that the voltage to the booth & DC to the bulb was correct, and I actually replaced both the lamphouse and rectifier (everything was new) thinking there was a problem. Kneisley lamphouse & rec. It just got to the point where there was nothing else to do. Never really figured it out and is still one of those mysteries. I will say that after a years operation it worked fine. I should have tried cutting the wire around the bulb...also I would have installed a solid state rectifier but this was before they were available...

Posted by Richard May (Member # 2627) on 12-13-2010, 11:15 AM:

So I changed the ignitor to the AC ignitor and right away there was a difference. The lamp was getting much harder to light each day up to this point. Now it strikes like a brand new bulb, even first time in the morning. You barely have to touch the manual strike button. I will try the caps in the other lamphouse when they come in. This has been a very strange problem and there doesn't seem to be just a single culprit. It may have been a combination of things.

Posted by Monte L Fullmer (Member # 2797) on 12-13-2010, 12:17 PM:

I'd call it that the DC igniter was on its last legs to operate, esp. after you switched out the igniter for that AC one.

Posted by Richard May (Member # 2627) on 12-13-2010, 12:34 PM:

The weird thing Monte, is we changed the ignitor with a brand new spare that we had and it was the same problem. Remember, this was happening in both lamphouses with numerous new bulbs. Some people say it was the bulbs, but THAT many? Also, if it were JUST the bulbs, you would think the AC ignitor wouldn't make that much of a difference.

Posted by Tony Bandiera Jr (Member # 2365) on 12-13-2010, 01:20 PM:

I think the AC ignitor makes a difference because the HV pulse it makes is a high-frequency RF voltage (which will jump the gap in the bulb easier) while IIRC the DC ignitor put out a single short, HV DC pulse.

Glad to hear you got it solved!

Posted by Richard May (Member # 2627) on 12-13-2010, 01:28 PM:

I definitely think that makes a big difference.

Posted by Gordon McLeod (Member # 33) on 12-13-2010, 02:10 PM:

Tony the "DC" ignitor does not supply high voltage DC but High Voltage AC at about 30-50khz depending on the tuning of the caps to the inductance of the coil and the length of the spark gap
The "AC" ignitors i am no fan of just like i never liked the neon glow tube ignitors in the strong lumex

Posted by Monte L Fullmer (Member # 2797) on 12-13-2010, 06:14 PM:

Now you know why I love those Christie IGA15M igniters being that they are AC igniters..They hit the bulb once no matter how old and what kind the bulbs are...
..just that they got a goofy designed autostrike design in them..

Posted by Gordon McLeod (Member # 33) on 12-13-2010, 06:50 PM:

It isn't that goofy it is the same as LP Associates
The goofy one was the first hughes/christie with a UJT firing a SCR to control the ignigtor

Posted by Richard May (Member # 2627) on 12-14-2010, 08:43 AM:

These DC ignitors just don't seem to give a strong enough "zap". Also, you have no control over the striking. There is no manual bypass.

Posted by Mike Moreno (Member # 4887) on 12-16-2010, 01:18 PM:

i have recently the same problem with one projector and we found that the igniter cause theproblem.
our dealer recamend to replace the igniter (the one that is white) for a AC igniter Highlight IIA AC Igniter Assembly IREM.

i have one IREM ASN 700 but i dont know if is the same than the one for STRONG projectors.
do you know a web site where i can see the Highlight IIA AC Igniter Assembly model?

mike moreno
mexico