Johnson-Disney Mark 1 Film Strip Projector Repair


The following notes are based upon a more detailed document written by Gavin Ritchie, repairer of the Disney Mark 1 lantern (projector) shown on this web page.
The lantern projector came from Keith Cutting (via this website author) as an assortment of parts and, although the parts included an instruction leaflet, it did not show even how to insert the battery, let alone connect up the various parts. Below is shown what was received:

The only thing inside the battery compartment was a metal strip which rises when the switch on the front of the torch body is moved to one side. The instruction leaflet says that the battery is "the type used being a standard 3-cell pocket lamp battery and 3½ volt bulb, preferably obscured". This website author had found a non-obscured 3½ volt screw thread bulb and had sent it with the other parts.

It wasn't clear, after 70 years, what type of battery was being referred to, but via an Internet search, a diagram of the battery was found together with instructions on how to bend the terminals:

A modern equivalent is shown below.

Gavin looked around on the Internet for another example of this projector with a photograph showing inside the battery compartment and was lucky enough to find a picture of something very similar.

 

The cardboard insert provides insulation to isolate the positive side of the battery from the tin body of the lantern. The switch operates the positive side. The positive terminal is the shorter brass strip on the left-hand side of the battery and the left side of the battery compartment has a three-prong spring metal device to contact the battery terminal. This is the bent metal part seen in the collection of parts above, immediately above the green film strip box.

Notice that the larger cross-shaped thin metal plate in the centre of the battery box was entirely missing from the parts which arrived from Keith Cutting.

 
   

The smaller bent metal part should fit onto the cardboard insulation using three bent metal tabs, though unfortunately two of the tabs had broken off from the part supplied.

To repair it, a thin strip of metal was fixed along the flat part of the terminal clip with a new tab at each end to fasten the clip securely to the cardboard insulator.

To the right can be seen the repaired terminal clip, with its new metal strip fitted and providing new tabs.

When fitting the terminal clip, its metal tabs pass through the insulator card and, unless prevented, are able to contact the metal lantern body and short-circuit the battery. Hence, there are two insulator cards - one of which receives the terminal clip and a lower one which sits in the bottom of the battery compartment to stop the metal tabs of the clip from touching the metal body of the lantern.

The large rectangular hole near the top of the insulator card is for the switch contact, which connects with a brass strip which rises when the switch on the front of the lantern is pushed to the 'on' position. This connects the positive side of the battery to the metal of the torch body and hence to the screw surround of the bulb. The screw end terminal of the bulb is intended to be in permanent contact with the cross-shaped metal plate (see internal battery compartment picture above), but this plate was entirely missing from the parts supplied. This metal plate connects with the negative terminal of the battery.

Based on the picture found on the internet of the internals of the battery compartment, Gavin drew out a similar cross-shaped connector onto paper and then glued this to a thin piece of sheet steel ready for cutting to shape using a fret saw, as can be seen below.

The right hand image (below) is the finished section secured to the cardboard insulator,
together with the positive terminal clip.

The finished battery box internals without and with the 4.5v battery installed.

The lens and film 'gate' tube is a simple friction push fit over the battery box front bulb and reflector housing.
Some straightening was required to the lens tube in the region of the film 'gate', as it was originally drooping downwards, presumably due to excessive force being applied when sliding the bright metal lens tube in and out, as required for focusing the screen image.

Gavin tried projecting one of the Walt Disney filmstrips using the lantern projector in a darkened room.
The filmstrips are printed on cellophane rather than being photographic film, but, with a good white screen and a new battery in the projector, the image is reasonably clear.

Gavin is now busy trying to build and decorate a box to the original dimensions.
The name of this instrument changed from 'Lantern' in the late 1940's to 'Projector' in the early 1950's.
"I decided that 'our' instrument was an early one and should have a box saying "Walt Disney Film Strip Lantern" and not a box saying the later "Projector". I have found a lid design for a "Lantern", but not any pictures for the sides of the box. I'll have another look around and if necessary just do the lid. Or maybe relent and do a "Projector" box with lid and sides. Dilemma!"
   

This page last updated: 2nd October 2020