Broadcast TV Slide Projector System

[Kat Manton]

Hi folks

I've started resurrection of something which I, at least, find pretty interesting but actually don't know much about. So I thought I'd start a discussion where I can report my progress and post some photographs as well as to ask if anyone can provide more information.

The system as it arrived here consists of an RCA TP-7 slide projector and associated electromechanical control unit, 24V PSU, 110V stepdown transformer, Link 102 TV camera (monochrome, 1" vidicon, 405/525/625 line) and control unit; plus a mains distribution panel and a mass of cables.

The RCA TV Equipment Section of The Broadcast Archive lists and details a lot of fascinating RCA gear, where I've found an external view of the TP-7 (a later one than mine going by the RCA badge) and another view of one with a carousel removed.

I've had the projector powered up after checking things over (so far, with the lamps, carousels and lens removed and all covers off), it's in fairly good condition internally and mostly seems to work. I'm currently tracing out a schematic for the projector and control unit, partly just for the fun of it. But, there's a fault I'm tracking down and I'd like to figure out how the remote-control sockets are wired and what to wire up to them. I also need to take the lens to bits as the iris has jammed; that could be fun!

I've yet to make a start on the camera as I've lacked a source of mixed sync and mixed blanking signals (that'll change once transport has been arranged for the SPG currently sat in Mike Phelan's garage.)

One thing I'm slightly puzzled about are the optical arrangements. I'm currently assuming that the lenses fitted to both the camera and projector are such that the projector can be shone straight into the camera. Looking at pictures of RCA telecine gear I've found that the multiplexer contains mirrors, no lenses. The Link 102 camera has a standard C-mount but the lens isn't C-mount and is screwed into an extension tube.

If anyone's interested, I'll post some pictures of the various components and report further progress as it happens.

In the meantime, are there any broadcast TV folk around who've used this kind of gear? I'd like to know what sort of things it would've been used for and how it might've been controlled when in use (originally at Anglia Television, going by the stickers on the two slide carousels.)

Cheers, Kat

[Sean Williams]

****** northerners! Knicking our heritage from down sarf! Anglia certainly does not cover Leeds! (yet!)

Would be good to see some shots though

[Steve_P]

Be a great help if you would. I'll look around for a circuit. (Not hopeful but you never know!).

Cheers,

Steve P.

[Kat Manton]

Hi,

As promised, I got my camera out

1. A view from above. The lens would be at the top of this photo screwed into the brass cylinder if it wasn't on my bench upstairs awaiting dissection. The lamp is located directly under that grille in the middle, light emerges either side then is reflected forwards through the slides. Next, the images are reflected towards "the cunning bit". One of the four mirrors is pivoted. When it's raised (as photographed) the image from the left-hand slide is reflected towards the lens. When it's lowered, the image from the right-hand slide is reflected towards the lens by the fixed mirror immediately behind the moving one.
2. Next, a view from the front.
3. No, I've not made a mistake and uploaded the same image twice. Spot the difference, in this shot, the moving mirror is lowered.
4. Finally a photo of the control unit, a fascinating assemblage of electromechanical gubbins.

Cheers, Kat

[Danny]

Wow this will keep you bussy for ages and ages but will be worth it and multi standard as well.Danny

[Kat Manton]

Hi,

Originally Posted by Sean Williams

****** northerners! Knicking our heritage from down sarf!

Heh... at least I'm preserving it!

Originally Posted by Steve_P

I'll look around for a circuit. (Not hopeful but you never know!).

Cheers Steve. I don't really need a circuit as it's fairly simple. It's just there's a lot of it, which makes it look complicated... you know what I mean...

I've made a bit more progress; after tracing more of the circuitry I found the fault. The RH carousel motor wasn't stopping when its associated cam-operated microswitch closed. I traced the wiring from the switch back through to the control box and found a NC relay contact reading open-circuit.

Now I've cleaned the contacts on this (and its partner while I had access to it) the carousel motor completes one cycle and stops as it should.

Then I found another fault. When a slide change is triggered, the mirror motor runs one way then one carousel advances; on the next change, the mirror motor reverses then the other carousel advances. But sometimes it'd get stuck, failing to move the mirror and advancing the same carousel again.

There's a rather interesting device involved, interesting enough for me to make an animation of it operating and attach it below. The metal actuating rod was sticking slightly, occasionally it went down the same slot it'd gone down previously. A small amount of PTFE dry-film lubricant restored correct operation.

(I've now "pulled an all-nighter" on this, it's way too interesting to leave alone...)

Cheers, Kat

[Kat Manton]

Hi,

I've spent most of my waking hours since the last post working on the projector. (It's actually an RCA TP-7A; I eventually spotted a label bearing model and serial numbers.)

Each carousel is supported at 3 points, each point using a pair of ball-bearings. That makes 12 bearings in total, all of which were siezed. I've freed them off with penetrating oil, cleaned them all out and packed them with fresh lithium grease. Now both carousels rotate freely.

I've also thoroughly cleaned everything. I dismantled the carousels then washed all the bits in hot soapy water. One of the "Anglia" stickers was damaged and starting to peel off; as that's part of the history of the projector, I stuck it back down with contact adhesive. The aluminium base-plate was filthy and had suffered from some corrosion but came up well with the aid of a Brillo pad and a lot of elbow grease.

At some point I'll need to revisit it. The motors and gear trains which drive the moving mirror and carousels need dismantling, cleaning and lubricating properly. Without dismantling; penetrating fluid, 20W/50 and aerosol lithium grease have managed to get everything freed off and moving. Apologies to our resident lubrication experts, I will do it properly! At least it's not likely to seize solid again and I'm not going to run it much in the meantime.

It's turned out better than I'd expected, the layers of grime concealed good paintwork. It's not perfect but I imagine it's now fairly close to the condition it was in when last in service.

The first picture below shows it running, projecting a small, perfectly-focussed (and over-exposed) rectangle on the back door. The pile of bits on the right are, top to bottom, 24V PSU, control unit, stepdown transformer.

Next, I need to tackle the camera...

Cheers, Kat