Newbie: DIY 35MM lamphouse using smaller lamp, CP650?

[Ethan OToole]

Hello! A bit of a newbie here looking into 35MM projection at home for fun. I don't have any hardware yet, but have been reading up on it. Got to tour a local theater recently and they had some of the older 35mm stuff stored there.

I'm sure it has been discussed before but I didn't see anything in the archives. Looking at a 35mm projector, would there be issues if I took something like a 400 watt LCD/DLP projector lamp and ballast system and built a custom lamphouse and docked it to the 35mm head? I would want to keep the UV filter of course, but could shed any 3 way prisms or spinning wheels. It would allow me to shrink the projector footprint heavily. It would be a nice short arc, and without any 3 way prism / dichro there might be a decent amount of light for a smaller setup? I saw talk of there being issues if the lamp is AC driven which makes sense. I would assume all the smaller projectors are running the lamps on DC generated via switchmode supplies.

Also, in prior postings I saw mention that the Dolby CP650 units tend to fail more often than the earlier series. I might have an idea as to what might go wrong with them. If I could find a malfunctioning unit that could read both analog and digital formats cheap I would be willing to take a shot at repairing one and publishing the fix. I have my eye on the SMD electrolytic capacitors that are on all of the boards.Any idea if there is a common failure?

Thanks!

[Jim Cassedy]

I can't give you any advice about your lamphouse ideas, but I have had a lot of experience working with the CP-650 for at least a decade. Most of the screening rooms & film festivals I work at use them, and I have one of my own. I have never had a problem with any of them. I believe, a long time ago, there were some issues with the power supplies due to the 'capacitor plague', problem. But that was long enough ago that all those 'bad' power supplies & caps should have failed and been replaced by now. I'm still in a position that gives me the opportunity to work with both film & DCPs, and the 650 is my "processor of choice", especially since it can still be configured to work with some of the earlier Dolby optical NR formats.

[Jay Brody]

I am having the same problem! I got EVERYTHING else working and the dang lamphouse isn’t working anymore for some reason. I, too, would love to ditch the lamphouse (which I cannot find ANY manuals on, ANYWHERE, and go the old video projector route myself. I have heard around that those lamps tend to not render the truest color though since as you noted that films are made for xenon projection. Lots of the video projectors use metal halide lamps or some sort of variation. I cannot get my lamphouse working. I bypassed the old rectifier, bought a welder/inverter and am using that to generate the voltage and amperage. What I cannot seem to do is get the console to recognize everything is all there and have the lamp power to turn on, which will allow the igniter to function. I still haven’t had luck. I had a short-term solution before I discovered I could use an inverter welder to supply the voltage necessary for the xenon lamp. My solution was to take out the guts on the interior where the lamp is and put an old Dukane 750 watt 35mm filmstrip projector in there and sat it on top of a 2.5 gallon bucket. It was pretty much exactly in line with the aperture of the film. I bout it on eBay for less than $50. (It’s the one with the long lens attached). It’s not bad because of the brightness (I have mine in the garage). You have to keep the lens on it with the lens in the farthest out position, closest to the output of the lamphouse to have it concentrated enough for adequate illumination. Anyway even with the built in fan on that little projector, it failed because of the fact that it was in the lamphouse, not outside of it like it would be normally. The lamphouse had the exhaust vent available but too much heat built up because the actual original lamphouse fans weren’t running, which ultimately caused the demise of that poor projector. It’s a shame there isn’t some sort of daylight-equivalent filter to put on one to solve the color temperature issue. I’ve also toyed around with possibly purchasing a xenon lamp that they use or used for medical telescopes since they seem they might be bright enough but I’m not sure how bright. Also I thought about a xenon car headlight lamp and just really focus it or something. I’m just spitballing. But maybe try one of those things. The filmstrip projectors online are very cheap and have an extremely small footprint and the best of all is that your print will never melt due to the lamp heat! Good luck and let me know how it goes! Also let me know if you have any ideas about how to get mine working. It’s an old Rentec LSX 2000 is all it says and a logo that has Film Systems on the side of the console. I’m going to make a new post about it myself. Best of luck!

[Ethan OToole]

Thanks for the info! So the CP650s aren't having any widespread age issues. The local theater that I got to tour recently seemed to be using all the same processors with the digital setups. Not sure if it was just running as a pre-amp with analog pass-thru or if it has one of those quad-AES/EBU cards in them that I read about.

I did look up the metal-halide light output characteristics versus Xenon and wow! Quite a bit of difference. Xenon has a much flatter curve in the visible spectrum which apparently is why it is desirable for projection and camera flash. LED arrays won't give point source, but they are using them in the moving light fixtures in the stage world with success. They also probably have strange spectral curves -- quick google looks like it. Not sure if there is an easy way to attenuate some of the peaks on the MH lamp output, but from what I know of precision dichros that friends buy for building laser projectors they get very expensive.

I did find that some medical equipment uses smaller Xenon lamps.

I saw all the Xenon car headlights -- my question is are they really Xenon lamps or are they lying for marketing and it's really a MH lamp?

[Mitchell Dvoskin]

I have a friend who mounted a halogen overhead projector bulb, that ran directly off of 120 volt wall current to the back of a Simplex XL head. It worked fine, the hard part was getting a bulb who’s reflector correctly focused the beam on the film gate for the distance required. He mounted a fan on the back opening of the XL for calling purposes.

While I have never personally seen this, I have read on other hobbyist forums about people taking the lamp and power supplies from Kodak Carousel slide projectors, since the bulb was designed to illuminate a 35mm frame, and mounting it on a 35mm movie projector.

[Helmut Maripuu]

Yes you can use xenon from a car but then you will have problems with the mirror, you need a 500 Watt xenon mirror. Maybe an old video projector mirror? And you can use parts from a Kodak carousel, but then you have same problems to focusing the mirror and three lenses and a lamp. Simplest solution to use a 250 watt 24 volt 25-50 hour lamp with mirror.

[Randy Stankey]

Theoretically, you could illuminate a projector with a flashlight but, in practice, that wouldn't get you very far. Would it?

A car headlamp might also work if you can mount it in the projector/lamphouse original reflector just the way a xenon lamp would have been positioned.

What if you made a lamp holder for a bare headlamp bulb and, somehow, mounted it in the original clamps that held the xenon lamp?
(The xenon power supply disconnected, of course.)

You might be able to put a metal rod between the two clamps that held the xenon lamp, affix the headlamp bulb to that and still use the projector's original reflector. That might also allow you to use the lamphouse's original focus controls to adjust the beam spread.

Neither would you have to do a lot of work stripping out and redesigning the lamphouse from scratch.

It would be a damn-sight better than a flashlight, too! Wouldn't it?

[Ethan OToole]

Another hobby of mine is playing with stage lighting systems and laser show systems. A lot of the moving mirror fixtures from companies like High End Systems (Lightwave Research) and Martin use MH lamps. I still have some Roboscan 1220's in storage which use 1200 watt single ended OSRAM bulbs and have reflectors in them. Then there are the Technobeam fixtures which use single ended 250/2 lamps. Thinking about it, the light output from the technobeams probably wouldn't be very impressive. These are MH lamps though, not xenon.

It might be possible to source reflectors from these types of fixtures though, and hot/cold mirrors. They usually are focused down internally to gobos / color wheels that might be 25-30mm in size.

The 1200 watt lights like the Cyberlights (208V+) and the Roboscan 1220s (115V or 208V+) tend to go for cheap because they are heavy and power hungry.

I did see there was real Xenon lamphouses for 35mm projection that were at 1000 watt.

[Mitchell Dvoskin]

There are real xenon lamphouses for 35mm screening room projection ranging from 500 watt to 1000 watt.

The picture below shows a 500 watt Kneisley "Pup" lamphouse behind a Marin MP-30 portable 35mm projector which was modified for the external xenon. The top of the matching rectifier for the lamphouse can be seen below the lamphouse. I think the model of the lamphouse is L-100. This runs on regular USA 110/120.

mp30x.gif

There also was the ORC 1000 self contained lamphouse with the rectifier built into the lamphouse that could run anything from a 750 watt to 1000 watt bulb. Also ran on regular USA 110/120.

The Kinoton FP-23X pictured below has a Kinoton 700 watt xenon lamphouse with a Kneisley rectifier built into the base along with the independently powered takeup.

kinoton_fp23x.jpg

There also was a Christie 500 watt vertical lamphouse for 35mm that ran on 110/120 volts.

[Ethan OToole]

Oh wow that The Kinoton FP-23X / Kinoton 700 watt xenon setup is sexy!

[Marin Zorica]

If you want to have colors on projection, use xenon lamp! While in high school i tryed everything like halogen, old projection lamp, hmi, etc, but not did have color gamount as xenon off course. And, that would be so cool is to find carbon arc lamphouse

[Steve Kraus]

Isn't old film gear cents on a pound by now? So why even bother?

[Ethan OToole]

Isn't old film gear cents on a pound by now? So why even bother?

Eh... in the eBay world the prices are high. At the actual auctions the prices seem low (Projectors @ $70, platter systems @ $40.)

So far I haven't found projection equipment for cents on a pound yet but can see it sold for that at auction (except for audio amps usually) recently.
I am mid-atlantic East Coast and looking.

I know that some people are hoping to sell the equipment off at higher prices and I respect that. I assume it will be difficult mainly due to lack of available content on film. I don't know the market enough yet and certain bits or systems are worth more than others usually.

[Stefan Scholz]

Film related items are, or were cents on the pound, Digitization and direct into dumpster is over for nearly10 years. At least it is still possible to find cheap items.
But the expensive part starts in the shipment or hauling heavy stuff.
We're all no commercial shippers/ exporters, so the price quote for shipping is rather high. If you're not doing it yourself, someone has to (crate and) pallet things and hold avail for collecting. You have to pay for it.

Picking up a (free) projector, having to rent a light truck, paying rent, fuel for a couple of hundred miles probably (and excluding time, motel, and meals for you and a friend), ends up in mid 3 digit numbers.
So best is looking around and wait for the occasion to come.