8mm Forum: Bell & Howell 1568 Xenon

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Posted by Maurice Leakey (Member # 916) on May 12, 2008, 05:13 AM:

I took my two Elmo GS-1200 projectors for service yesterday and the engineer showed me a 16mm Bell & Howell that he was currently working on.

I thought I knew all Bell & Howell models but this was completely new to me. It was an American 115v model 1568. A zenon 350 watt lamp, slot loading and push button controls.

Most surprisingly everything was in the standard size green TQIII, even the power unit, which on the earlier 666 is a separate "box" upon which the projector sits. There was even a socket for "changeover."

Has anyone got one of these and were any 240 volt models produced?

Posted by Simon McConway (Member # 219) on May 12, 2008, 05:51 AM:

I had one of these but the circuit board failed (in fact, it never worked!) Spares were unobtainable, and with the seriously high voltages involved in striking the lamp, I didn't think it was worth it. I have my B & H 666s with MARC 300 arc, so stuck to them. I am sure Keith uses one of these machines at Ealing Maurice.

Can I ask who you go to for your GS1200 servicing. I do all my own B & H stuff, but not Super 8 as I've not had the training.

Posted by John Whittle (Member # 22) on May 12, 2008, 06:01 PM:

The B&H 1568 was a very popular machine in the US and used by a large number of schools and institutions for large screen projection. The Marc 300/350 lamps we cheaper than xenon but have a very short life span in comparison so the cost per hour is high. The Marc lamps are no longer made and GE made all the power supplies so you pretty much have to find a parts machine if anything is wrong with the lamp power board. The previous model used a power supply that was separate and the projector sat on top of it. Besides B&H, Kodak, Victor, and Eiki made machines for that supply.

I don't know if any 240 volt machines were made.

John

Posted by Jean-Marc Toussaint (Member # 270) on May 13, 2008, 12:56 AM:

Simon, the Xenon B&H Keith uses at the BFCC has indeed push down buttons but I'm not sure it's a channel loading machine.

Posted by Steven Sigel (Member # 21) on May 13, 2008, 11:36 PM:

Two clarifications -- as John mentioned, the 1568 is a MARC (Mercury Arc) machine - not Xenon... I don't believe that B&H ever had a Xenon machie (but I could be wrong).

Also - pet peeve of mine - it's Xenon, not Zenon...

Posted by David Kilderry (Member # 549) on May 31, 2008, 10:41 PM:

The Gemini lamp model B & H push button models were sold here, but required a separate transformer as they were 115v, we are 240v in Australia. They did not require a heavy power supply/rectifier box like the 666.

I think the Gemini lamp machines are better than both xenon or marc 300 projectors. Great light with less bulk and operating cost.

David

Posted by John Whittle (Member # 22) on June 01, 2008, 01:36 PM:

The Gemini is just another name for the MARC lamp. If you calculate the lamp cost per hour of use, you'll find it's much more expensive then Xenon. The 1658 is a nice machine, but be aware that no MARC/Gemini lamps are being made and some have claimed that the lamps have a "shelf life" so NOS might eventually be a problem.

John

Posted by David Kilderry (Member # 549) on June 03, 2008, 07:32 PM:

John,

I agree with your comments and was rushing out the door at work when I made the post.

I realise that the Marc 300 and Gemini series are essentially the same metal halide type lamp. What I meant to say was the 1500 series of B & H projectors with the metal halides were a better machine in many ways than the older 666 version. Far less bulky, less noise and with better hot air extraction in my opinion.

I can't find any reference to it now but I understood the later EZG metal halide 300 series lamps that were forst called Gemini as opposed to Marc 300 had improved dichroic qualities allowing even more of the heat energy to pass through the reflector and were more efficient at directing the light forward; have you heard this?

I must admit I don't mind the xenons especially the Eiki range, but in professional use we found that xenons certainly did require alignment more often (especially as they were lugged around often) and the xenon light output would trail off almost from the word go. Set up correctly however the light was excellent.

We found many operators would continue to use high hour xenons because "it still works!" but of course the lamp had long since passed its use-by hours and light output was only about 40% of what it was when new.

I admit I was not paying the bills when I mostly used the 16mm xenons and Gemini machines, but the Gemini light output was always brilliant and clean right up to failure. Both lamp types do not like "hot strikes" and running either for a 2 hour feature is much better than running five 7 minute cartoons with a lamp switch off and re-strike between each one.

Both xenons and metal halides do have a shelf life according to the manufacturers; I do not know how this translates into decreased performace however; I imagine a 5 year old lamp may be OK, but a 20 year old lamp could have some problems.

David

Posted by Steven Sigel (Member # 21) on June 03, 2008, 10:49 PM:

Hi David,

What you are saying is the exact opposite of what I've experienced, and what others say as well --

you said that the xenons trail off in light and the MARC lamps don't -- My experience is the exact opposite -- if a xenon strikes, the light is at pretty much the same intensity old as new, while the MARC lamps degrade pretty rapidly...

Posted by Roy Neil (Member # 913) on June 04, 2008, 03:49 AM:

I didnt want to be the first to contradict, however I have to agree wholeheartedly with Steven's comments.

In my experience - MARC output diminishes dramatically with each strike of the bulb, while xenon does not suffer these same symptoms. Xenon bulbs tend to require more energy to produce the same light output as their lifespan diminishes ( as the bulb becomes 'spent' )

(edit) Additionally, most xenon lamphouses have no difficulty with a hot restrike.

Posted by David Kilderry (Member # 549) on June 04, 2008, 05:58 AM:

Steve and Roy,

I am not surprised you have found differently. Gemini lamps seem to just lack the life they seemed to have 25 years ago. Perhaps they are old lamps sold today? My experience relates to both portable (Eiki, Hokushin) and pedastal or permanent installation (Philips, Bauer, Fumeo) xenon projectors .

Don't get me wrong, I am not knocking xenons and own many xenon projectors myself; I have found however that many people with xenons tend to never change them because the lamp keeps working. They have not realised however that the light output is less than half what it used to be.

I must admit to changing out the Gemini lamps at around 50 hours when I used them, so I take your point that the light may well drop dramatically after that point. I have had Gemini lamps fail before this however. Please understand that I am talking 20 years ago and more; the situation today with EZG lamps no longer being made will only increase their cost. I remember them being affordable back then.

Despite what is available, I use a B & H 1680 Charcoal slot load almost exclusively at home these days. 250w light output is fine on my home screen.

Both Osram and Ushio/Xebex have excellent information regarding xenon lamp light output charateristics and the fall-off in output as the hours tick by. Kodak also had good information on xenon lamp light fall-off in with their theatrical screen check certification programme about 10 years ago.

I wish I could find similar information on the Gemini/Marc 300 lamps now. I recall an info. brochure put out by GE I think explaining the metal halide technology and characteristics. Probably a good bit of self promotion too!

Either lamp in the hands of a knowledgable projectionist will provide brilliant light, alas at much higher cost than a 250w QI lamp.

David

Posted by Josef Grassmann (Member # 378) on June 04, 2008, 07:26 AM:

GE did publish technical information on their Marc 300/350 bulbs.
I am searching for that sheet for years now, without any sucess.
If the power supply for Marc 300 is in good condition and switched on for min. 90 min. than most user exceed 60 hours life.
If you make a break between too reels let the bulb burn, even if break last 20 to 30 min.

Posted by David Kilderry (Member # 549) on June 04, 2008, 07:55 PM:

Thanks Josef, if you find it let me know. I recall it was very interesting reading. Those are the sorts of facts I'd like to read again.

David

Posted by John Whittle (Member # 22) on June 05, 2008, 08:37 AM:

One of the major problems with the marc 300/350 was the power supply. First the lamp took five minutes or so on start up to come to full power. Second they were place in portable equipment which often ment they were shut off without cool down or shut down between reels which shorten life.

But the biggest problem is that the power supplies were all made by GE and serviced by GE. In face there were some special parts in the power supply (transformers and coils) which were only made by GE and only available from the GE service department. Even equipment makers sent the power supplies back to GE for repair so if something goes wrong today you have to find another unit for parts or swaps. Since I don't think service data was ever published outside of GE, you have to swap or experiment.

John

Posted by Josef Grassmann (Member # 378) on June 25, 2008, 03:39 PM:

every year we repair some power supply units suitable for Marc 300/350 bulbs. Most of them are used on 16mm Bauer (Rank Aldis) projectors and sometimes for Bell & Howell machines.
We still have the special spares available to do the job.

People still using Marc 300 projectors as they are cheap compared to HTI-version. Most of them use Marc 300 about 10-15 hours/year. Bulb replacement takes place every 4 to 5 years and costs approx. 1/3 compared to HTI. A few run up to 50 hours/year.

Posted by Mike Carro (Member # 933) on August 14, 2008, 05:39 PM:

I have a like new 1568. Everything works perfect. Except..
I can't get even focus across the frame. Supersharp in the middel but blurs towards each edge. I don't see an adjustment by the lens bracket to adjust the azimuth or whatever would be the right term to get the back of the lens parallel with the gate. I'm only using it for short throw, probably 12 feet. Could that be it?
Any help is appreciated.

Posted by John Whittle (Member # 22) on August 15, 2008, 08:58 AM:

The shorter the focal length of the lens (instead of 2inch say you're using 1 inch lens) the less the depth of field and the more critical the focus and parallel adjustment of the lens to the gate.

If there is nothing "loose" in the gate and the lens swings properly, there should be a "stop" screw adjustment that sets how far in or out the lens is when the gate is closed. If you carefully check which side is out compared to the middle with a focus chart you can figure which way you need to move that screw. A little goes a long way and it's trial and error.

John

Posted by Mike Carro (Member # 933) on August 15, 2008, 11:32 AM:

I didn't see a set screw per se. I see a screw that would adjust the spring that keeps the lens in place. Do you mean that?
thanks
PS I'm using a 2 inch lens.

Posted by Hugh McCullough (Member # 696) on August 15, 2008, 11:38 AM:

Mike.

If you focus the edges of the picture does the centre go out of focus?
I had the same trouble on an EIKI, and the cause was the film bowing slightly in the gate.
Centre of frame was closer to the lens than the edges.
The problem was too much side tension.
Can the side tension be adjusted?

Posted by Mike Carro (Member # 933) on August 15, 2008, 11:13 PM:

That sounds more like the culprit, I'll try that in the next few days to see if there is something to adjust.

Posted by David Kilderry (Member # 549) on August 22, 2008, 11:51 PM:

If you have another lens, try that, it may be your problem - loose internal element.

David

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