Royal Sound Master Model 6 Wiring

[Kyle Mikolajczyk]

I am in the process of trying to restore an old Simplex Regular. Film runs fine through the projector and we get a good image. The problem is that I cannot figure out how to supply power to the exciter lamp and how to wire it up to an old CP-55 for the "Royal Sound Master Model 6" sound head. Any documentation or guidance would be greatly appreciated!

[Mark Gulbrandsen]

You need a separate exciter lamp supply of about 6 volts at 5 smps, adjustable, look on Epay. and a stereo solar cell to fit the Royal Sound bastard. Good luck finding that last piece, no one ever made them for that model. You will likely have to adapt some existing stereo solar cell to it. Then you need all the alignment films, an oscilloscope, and spectrum analyzer to get it all set up correctly. A mono solar cell would be easier because they are larger and often you can jam it in place inside the photo tube housing with some foam rubber right in the spot of light the track creates.. Too bad it was not even an older RCA sound head... Then it's easy.

https://www.ebay.com/itm/XELAMP-Exci...AAAOSwNKVXMiau

[Kyle Mikolajczyk]

Thank you for the response! I dug around and found an old Kelmar Exciter Lamp supply. I have attached a photo; does anyone know what the pin out is for the AC in? Having difficulty finding a manual.

[Gordon McLeod]

That soundhead worked best with a 9v4amp excitor lamp BXM Kelmar is still in business give them a call. They even used to have stereo cells for the model 6

[Tony Bandiera Jr]

Your best bet for the AC input is to open the unit up, take out that Molex socket and wire a power cord directly to it. IIRC the hot (black), neutral (white), and ground (green) wires are all there and colored as I mentioned. I used to have a few of the power cords for this exciter supply in my junk pile, but probably not anymore.

[Kyle Mikolajczyk]

Upon opening it there are in fact 5 cables. I think the white green and black are the respective AC counterparts, but what would the other two cables be then?

[Tony Bandiera Jr]

Yep, Black white and green are the AC input. I do not recall what the two others were for (and I really seem to remember the older units not having them). It is possible that they are duplicates of the DC output, or are used for remote switching. If you have a multimeter, try to read from those two leads one at a time to each of the output terminals.

In any event, I see no harm resulting if you connect power and see if it has the DC out on the screw terminals.

Looking closer at your picture of the inside, I see those red and orange wires going to something on the top right...what is that? Can you get a better picture of that side of the internals? (Those wires might be for remote turn on...)

[Kyle Mikolajczyk]

Here is the photo, thank you for the help. I am curious, I will power the exciter lamp. But what I don’t understand is what gets connected to the CP-55 in this case. I don’t see any connectors on the solar cell? Attached is what I believe is the solar cel

[Tony Bandiera Jr]

First, that's not the solar cell, that is the slit lens assembly. Put it back in the soundhead, you will be adjusting that later.

As for the exciter supply, tracing the wires in the pic, it looks like it is for some sort of remote switching of the DC exciter output, but I think that the way it is wired up on the output terminals, you can just ignore them. The orange goes over to one side of the switch (which should be something like off (center position) Normal and Emergency. Normal puts filtered and regulated DC on the exciter, emergency is used when the DC supply fails and it puts unfiltered AC at about 5 volts or so on the exciter.

So again, you can most likely ignore those two wires.

I was unable to find that supply on the Kelmar website, but if you contact them directly they should have all the info you need in the archives. They are generally good about product support.

[Dave Macaulay]

When was this last used? It may have still had a PE (photoemissive) tube in there. These are a vacuum tube with only two connections - one to a coated curved plate in a half circle around a central metal rod. A pretty high voltage is put across these (plate negative) - maybe 200VDC? - and when light photons hit the plate electrons jump over to the rod. The DC voltage is blocked by a capacitor, the AC signal from the light passing through the sound track goes to the sound system.
Those went out maybe in the 50s or 60s?
After that silicon photoelectric cells were used which turn light into electricity directly so the high voltage isn't needed and their signal can go into a preamp more or less directly.
Stereo meant a dual cell and more careful alignment of the slit lens, cell, and film path.
Then re-coating, re-exposing, and redeveloping color prints to add a silver soundtrack emulsion became unpopular due to its complexity and cost plus the hazardous waste chemicals... so after some trials sound tracks became cyan instead of black but white light traditional exciter lamps caused poor signal to noise - red LED exciter lamps were needed.
Then a few years later digital took over... and thousands of 35mm projectors and platters piled up in scrapyards. So your beer can likely contains some aluminum from a film projection system.

[Kyle Mikolajczyk]

Thank you for the help with the exciter supply. I actually found the old molex cable for them! The wiring was close with what you said, but the orange wire was actually correct. If I recall the 3 pins that were needed were the 3 on the bottom or top, and the wiring was self explanatory. I got the exciter bulb to light and I then realized that the photo cell was missing. I looked around and found another photoelectric cell which looked like a chunk from a solar panel and wired it up. Presto, we have sound! Here is a link to the successful test: https://www.youtube.com/watch?v=wgD9ibLcxH8

Unfortunately, the solar cell was mono. While I am happy this works it would be much preferred to have a working stereo cell. I have attached the photo of another sound reader from another projector that is currently collecting dust and not assembled, this one looks to be a kelmar stereo reader. Do you think we could remove the dual cell and place it with the current reader? Thanks again for all the help with the project!

[Gordon McLeod]

The problem would be the bracket
the RCA soundhead is far better than the model6

[Kyle Mikolajczyk]

What would you suggest to do? I think its possible to disassemble the Simplex and put the entire soundhead (container? The big metal enclosure) in place of the royal sound master? I am not quite sure how much effort that would be. I was curious if it would be possible/advisable to swap the internals but not the enclosure.

[Sam Chavez]

The actual dual solar cell bracket shown in the RCA 1040 soundhead can be bolted to anything with a similar and conventional sound drum but a base bracket would have to be fabricated to get the solar cell head to the exact correct location. You should use the RCA soundhead if complete. It would be way easier and a better soundhead.

[Dave Macaulay]

Depends on the projector and drive on the RCA, is it the same as is used on the Soundmaster? May not be easy to get the correct drive gear if it doesn't work as is. And then there's the bullnose...