Projector SO CLOSE to being setup!

[Walt Shires]

I did find these unknown status Kelmar solar cells in a junk box in the anti-booth. Perhaps useful? The arms are gonna be different, would probably be a bit of a challenge to swap the cells themselves.

Someone here with more experience might know if these can be retro-fit to a Century C. I don't know what unit they would have come off of, perhaps our prior projectors before the Century JJs?

solar cells.jpg

Thank you for looking! Those cells look like one that I have in my junk box - which I believe is a mono cell. Either I upgraded or I was just lucky when I grabbed the stuff around the projector - I don't remember.

I do remember that I saw a message on some type of film forum that this movie theater was being remodeled to make way for a gym, and the owners offered for anyone to take the film stuff. It was the Belmont Theater in Belmont CA. My brother in law lives there remembers going to it when he was younger.

Here is a link to a short writeup about it.

https://cinematreasures.org/theaters/3395

I think it will be worth trying one of the reverse scan readers that Josh has. Then for optical tracks I should be good.

[Josh Jones]

As for the reverse system - do you need a different audio decoder to use those? Is there a benefit or is it just a different way that it's done? I only saw in the manual for the sound head (I think) that there was such a thing so don't know anything about it.

Anything made after 2005 or so will have cyan optical soundtracks, which your incandescent reader will not reproduce well. Reverse scan has the advantage of better stereo separation and usually much better frequency response than a forward scan system. There is no change as far as the processor is concerned, as the standard preamp connections are used to interface with the reverse scan reader.

[Ryan Gallagher]

This is what the bracket that holds the solar cell looks like:
The only thing I notice is the audio is very compressed - but, maybe that is because it's trailers. It's sort of loud with little dynamic range (if that makes any sense.) I don't know if that has to do with the solar cell getting rubbed like it did. It seems like there is proper signal coming off that side of the cell (I think it's the left channel) but... I know I should try to acquire another cell now that I have that impedance drum fixed.

I have a box of trailers - a long time ago (20 years) I bought TON of them for around 50 cents each. I think I have a 100 or more. I have 2 features - the cheapest one you can get (dice rules) and one of the Star Wars ( the 90's ones).

[Snip]

But, currently I don't think any film that I have has digital data. (maybe the Star Wars does - it came with a DTS CD)

You are still early in the tuning stage, so it could be anything, but if I knew you had a good solar cell and a tuned system and heard you say "It's sort of loud with little dynamic range", I would immediately suspect perhaps the wrong stereo format. Depending on the vintage of your trailers you may have mostly Dolby A-Type tracks (which seems likely considering you said none of them have digital tracks). Stereo A-Type sound a bit like you described if played in the incorrect Dolby SR format (5), try some again in Stereo A (4) and see if that compression/volume sensation goes away? Try mutiple trailers from different eras. That Star Wars one with DTS will definitely be SR (5).

Getting that replacement cell, head, or whole assembly will certainly help you rule out the solar cell damage.

[Walt Shires]

This is what the bracket that holds the solar cell looks like:

Screen Shot 2025-08-25 at 7.49.01 AM.png


The solar cell is glued to the clear plastic and then the wires are sort of caulked in to the black bracket in the front. When you unmount the solar cell piece - the wire are still stuck to the overall bracket.

As for the reverse system - do you need a different audio decoder to use those? Is there a benefit or is it just a different way that it's done? I only saw in the manual for the sound head (I think) that there was such a thing so don't know anything about it.

The current setup is a 9V incandescent bulb - with a DC/AC power supply. It's running at 7 volts.

I have done the setup according to the CP650 manual - (that previous photo was before the setup) and the lamp lens is close to the film, but it is focused now. I did it all - moved the bulb so the filament is in the middle, run the test films and tried my best to see the stuff on the oscilloscope (it's not as clean looking as the pictures in the manual - or is that just me and my setup?) and I've run the sound into my theater. It sounds descent - The only thing I notice is the audio is very compressed - but, maybe that is because it's trailers. It's sort of loud with little dynamic range (if that makes any sense.) I don't know if that has to do with the solar cell getting rubbed like it did. It seems like there is proper signal coming off that side of the cell (I think it's the left channel) but... I know I should try to acquire another cell now that I have that impedance drum fixed.

I have a box of trailers - a long time ago (20 years) I bought TON of them for around 50 cents each. I think I have a 100 or more. I have 2 features - the cheapest one you can get (dice rules) and one of the Star Wars ( the 90's ones).

My current idea was really just to watch trailers and such and then maybe get an interesting print or two. I don't really have much of a plan beyond that. I "rescued" the projector and some assorted stuff in the year 2000 and I had it running in my garage that time, but then I moved and that was it. Been toting all of it around for 20 years now. I've just always wanted to get it back up and running and we just recently built a theater where I could do it. The theater is a "normal" modern home theater with a laser projector, atmos speaker setup etc... the 35mm is for fun. I worked in tech for almost 20 years and am one to those that just likes older tech things now. For example, I found a 1971 jukebox - and spent a few weeks getting it up and running. It's these sorts of projects that are fun to me.

Film stuff is maybe a little bit closer to home - I did go to SF State in CA and graduated with a good old fashioned film degree! I cut my senior film on 16... so building up reels of trailers is enjoyable/nostalgic.

Ok - long way around saying that the optical setup is the setup now and I'll continue to search for a Cat 701 and then add that to the setup. But, currently I don't think any film that I have has digital data. (maybe the Star Wars does - it came with a DTS CD) So I don't think I need to be in a hurry about it (other than the 20 years it took me to get back into it _ I see everything is harder to come by now and is a lot more $)

[Tim Androes]

an observation...the slit lens in your soundhead (the black tube to the left of the the sound drum) looks to be out of alignment...maybe too close so that won't help your sound any

a question...what kind of film are you planning to run? is it going to be modern film, say from about 2002 and later?

another question...what is the light source in the soundhead? is it a filament light bulb or is it an LED source?

[Josh Jones]

triangle base is RCA, the three hole c mount is a simplex. Two hole C is Century, I believe. I have a box of used Century BACP reverse scan kits I pulled from a theater that closed. PM me if your interested.

[Ryan Gallagher]

To me, it looks like the mount on the left bottom. Unfortunately, the part-number on that picture seems to be broken...

That mount looks close to mine yup. Of course DX-1073 (if that is what it is saying) is not in their list. But Kelmar is still around. For Walt I would just advise reaching out to them for a Century C transducer or assembly (DX1071 or DX1074 assembly)?

The top mount pictured is more similar to Walt's, but is obviously a Simplex... there are not photos of every one, but I would assume a DX-1071 is all he needs, just the head assembly for Century.

[Marcel Birgelen]

bts.png

To me, it looks like the mount on the left bottom. Unfortunately, the part-number on that picture seems to be broken...

[Ryan Gallagher]

I did find these unknown status Kelmar solar cells in a junk box in the anti-booth. Perhaps useful? The arms are gonna be different, would probably be a bit of a challenge to swap the cells themselves.

Someone here with more experience might know if these can be retro-fit to a Century C. I don't know what unit they would have come off of, perhaps our prior projectors before the Century JJs?

solar cells.jpg

[Josh Jones]

My office doubles as my booth. I have an inline fan that blows out the eave, and even that didn't help that much with the heat. I added a mini split, now the booth stays at 72 during movies. Remember, pulling air from one space must be replaced from somewhere, and that somewhere is usually unconditioned outside air. The tighter the house, the harder it will be to get makeup air.

[Walt Shires]

Yes, I have a duct with a fan in it that pulls air through the lamphouse - it's not going outside yet... I figure I'll see if there is a heat issue with the 1kw bulb. If there is then I'll deal with venting it outside then.

That photo makes me think about maybe I could get my lens up a little higher!


I'm now just trying to get an oscilloscope - so I can get to lining up the audio. So.... another little delay.

[Ryan Gallagher]

Good progress. Yeah at the right price those 650s are quite a steal these days. Having all drums and rollers turning freely is definitely a must. Good catch on the optical reader flywheel bearing.

Have you installed an exhaust path and blower yet? Now that you are firing xenon (even a baby one) you might want to implement sooner rather than later to protect your reflector, even if just temporarily blower exhaust into the same room.

On the room height arm subject, I wouldn't worry too much... you can get really creative with the feed reel location at a later date if needed... just check out Brad's setup or that one from Piazza Maggiore shared recently. if you switched to a feed arm instead of the magazine, you can usually cant them forward or backward enough to make room for a taller stack.

CR-21-Giu-2025_Piazza_Incontri-ravvicinati-22.jpg

In fact your thoughts about a 701 aren't really in the cards until you switch away from the magazines. I've never seen a magazine mounted on top of a dolby digital reader, but anything is possible! If you wanted to preserve the magazines a mod that puts an internal SRD reader elsewhere might be required.

We might actually have an older style solar cell floating around in our back booth. Will check soon.

[Walt Shires]

Thought it was time for an update on my projector project - just for folks who enjoy seeing this kind of stuff (like me!)

With the luckiest eBay find of all time, I was able to get a 1KW xenon power supply complete with built-in igniter.

IMG_0680.jpg
I then bypassed all the circuitry in the Lamphouse and basically just went straight to the bulb with it. The Christie lamphouse is now just a shoebox to hold the bulb. I found a new 1kw ORC bulb and installed that with some extensions made from metal pieces and hose clamps to make the smaller bulb "longer" to fit the holder which I'd assume was designed for a 3 to 4 kw bulb. It fires right up and I have the light pattern pretty smooth. Here are the ugly bulb extensions - but, they work and are very solid.


IMG_0679.jpg


For the audio, with the advice of another forum user here (Ryan) I got a CP650 which will do the analog optical sound and can handle digital if I ever get there (I'd need a CP701 reader or such for that)

IMG_0676.jpg

I just made some cables and got it working only to find out the sound was terrible so I started the process in the manual to do the entire calibration/setup. I don't know how I ended up with them, but I have the test films. I have one that is dolby tone on one side and pink noise on the other. And the buzz film and a 151. I also have a "sound focus" film. I'm not sure what the last 2 are for but will figure that out over time.

While taking apart the audio section of the projector to clean the lens etc... I discovered that the solar cell had been damaged..

IMG_0669.jpg

I was able to figure out the impedance drum was moving in and out and when it did it could touch the solar cell.

IMG_0678.jpg


I also discovered that it was awfully hard to move and upon further inspection discovered that one of the bearings was seized - so that is taken apart and I've ordered some bearings that will hopefully fit.... if the harbor freight dial caliper is accurate enough! When I put it back together I believe I can adjust the thrust bearing a little tighter then the drum should not be able to move and touch the solar cell.


As for the damaged cell.... I'm going to try to shoot the light at the lower part of the cell and hopefully it will work. (even though the manual says to shoot the light at the upper 3/4 of the cell) I already looked at eBay and general google search and don't see an solar cell around. (if anyone knows of one I might need it!) Next step - I'm looking on marketplace to find an oscilloscope.

So... the current status is the light is sorted and the sound is on the way. Next step is to cut the hole in the wall. But.... I think I'm going to do a final check with the long ams and 6K reels and see if I were to get a 701 if there is enough room before I hit the ceiling. Little stuff like that could be a huge bummer later!

Anyway - there ya'll go - and if anyone has any input/advice I'd love to hear it. My plan is to get this all up and running and then begin doing special "film nights" just to try and keep it alive in my tiny little corner of the universe!

[Mark Gulbrandsen]

The only reflectors I ever had trouble with six to nine months after install were Kneisley Xenex 2's. The issues were with the actual coating peeling off deep in the reflector when running a 4kw lamp, and the reflector manufacturer fixed that issue. Never had issues with Super Lumex either as long as the air flow met specs. It's a different story on the small switcher before Strong derated them tp 2500 watts.

[Ryan Gallagher]

I never saw a glass reflector in a Super-Luim-Ex before, and I've been working with them since they first came out. If you have a photo or brochure with one I'd love to see it.

I'm not aware if glass was a thing with them, in other threads people just talked about metal being more prone to deformation when trying to use various lamphouse alignment tools. But they could have been referring to other lamphouses.