Some consoles such as Strong, feature an exhaust stack micro-switch with paddle which cuts out the rectifier, should the exhaust be insufficient. The result of this, however, has been that the theatre staff usually abandon the performance and call us with a lamphouse problem. Although we are assured, when we ask, that the lamphouse exhaust fan is turned on, there have been too many instances where, service calls to turn on the fan switch solves the problem.

Moreover, many of our older-equipment booths do not have the above mentioned micro-switch, or some "genius" has simply solved the problem by by-passing these switches either electrically, or by mechanically (using electrical or masking tape to hold the switch up).

With some of our theatres being equipped with 7K bulbs, the results are not only expensive in terms of shortened bulb life, but in heat damage done to reflectors and lamphouse wiring, not to mention cracked heat filters.

The obvious solution should be better staff training, but with most of the booth personnel are there only as a "summer job" (projectionist licensing having been done away with in Ontario), this would be a never-ending job.

Being a realist, I realize that this personnel situation is not likely to change in the near future (if ever), thus other solutions to the problem must be found.

One solution I am considering is to mount a relay in the electrical breaker panel such that picking off one leg of the 3-phase output of the console breaker (and neutral) to power the coil, the contacts of said relay would parallel the fan switch. Thus, if the console is switched on, the fan is on.

Should it become necessary to service the fan during the show, the breaker for the fan may be switched off (for quick repairs - e.g. belt or pulley changing).

The breakers, by the way, are used as power switches to turn the consoles off at night - (not a good practice, I know, unless they are designed to be constantly switched, but one step at a time).

I would very much appreciate your thoughts on this, or any other solutions you may have. Thank you.

I would be very cautious of by-passing the exhaust fan fail safes, or alterating them for any reason - or circuit breakers! A lot of lamphouses require an exhaust fan which holds up that fail-safe in the duct work! Notice that some lamphouse doors also have a second fail-safe to prevent the bulb from striking should the door be opened. There are also decals that manufacturers are placing on lamphouse doors concerning the bulb cool-down time before the door can be safely opened! Christie even puts a decal on their projector stating that it is not to be used with nitrate film! I would make up a scheduled maintenance calandar and ensure that the exhaust fan bearings are getting greased at regular intervals, and that the belts are being changed as needed. Also, on the main circuit breaker pannel, highlight the breakers that are to be turned on/off every day. I would think, that since you have a service company, that you may be in for legal trouble should someone get hurt because of your mod. It is the responsibility of the theater to at least make an attempt to have someone with something between their ears in the booth! If they get hurt, then don't let it be your fault! CYA! At my old theater, a roof exhaust fan would sometimes fail, and if it was broke-broke, we would open the back of the lamphouse, put a big floor fan, and tape up the failsafe - just so the show could continue! We always managed to get the exhaust fan fixed between shows, or by the next day at the latest! Also, our exhaust fans were very strong, so the bulbs always stayed relatively cool!

Some setups using 208/240 volt PS contactors will need a relay to control the feed to the exhaust blower, especially if the exhaust blower is 115 volts. (such as in some IREM power supplies). Also, I might point out that the goofy interlock the Strong International consoles use a DC interlock loop fed from the switcher power supplies. This could be a major problem. If so, perhaps the Projector motor feed circuit breaker could also accomodate the exhaust blower as I have indicated above.

If there is a will, there is a way.

We also wired up a "bypass" toggle switch to bypass the lamp's vane microswitch. We did this because they get clogged with dirt and won't turn on. Of course, we rarely told anyone about this switch except people who knew what they were doing.

Now, your situation seem a bit akward because while you can wire up something to prevent accidents, you also can't make people smart and troubleshoot correctly. You also can't control what some well-meaning fool will do with the wiring.

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I agree that the sail switch (which is an integral part of the console) should NOT ever be bypassed.

There is a local switch at the motor itself which allows for disconnection for belt changing, ect.

The switch I am talking about by-passing is the wall switch which turns on the roof exhaust. This switch SHOULD be turned on at the beginning of the day, and turned off (with auto time-out) at the end of the day. This is the switch that some of them tend to forget.

I understand your point, Paul, but I fear that this might involve another abandoned performance. Besides, I am not sure I want to run two motors through the TA-10.

I would like to fashion it in such a way that they do not have to remember to turn this switch on, it is done automatically for them.

The 7K consoles are often fed by a 60-amp breaker. Not sure I want to run this line up to the exhaust fan. Should the exhaust motor short, it would provide an entertaining fireworks display for those in the parking lot, but might really piss off the fire-insurance company.

These people who run this equipment, unfortunately, do not have the dedication and passion for the industry that is found in those of you on this forum.

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And people still wonder what ails the motion-picture exhibition industry? The bean counters just don't get it.

One premature lamp explosion or one lost show will more than offset the savings in not paying enough to retain skilled (or even just competent) projectionists.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

I've never seen where a bulb lasted longer or performed better when the cooling fans were left on (after the end of show.) I suppose there are some lamphouse makes that would contain the heat; I've never seen one.

Actually (sad to say) I don't think it does. Equipment is pretty reliable nowadays, and with modern automation systems that shut down for platter wraps, fans that stop turning, etc. usually very little actual damage is done. Of course, patron good will is severely affected, but since that's a cost that can't be easily be counted, the bean counters ignore it.

Here in the northeast, I would guess a theater company would have to pay at least $30,000 a year for just competent operators. Things are just too expensive around here, and I think that would be the mimimun to keep someone interested. (By way of comparison, the average price for a 2 bedroom house on 1/4 acre here is now $250,000.)

We don't even come close to loosing that (from incompetence.) Even if a show is lost, it's only 10% of the box office. About three years ago, someone on r.a.m.t newsgroup semi-proved (meaning the numbers they cited were reasonable) that not maintaining and just replacing a projector after 6-8 years was actually cheaper than paying for it's maintaince. (It was mostly labor costs, not parts.)

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