As soon as this blog went live, one of the the first requests made was to look into the traditional Blockbusters game board – a sophisticated setup that implied a massive complex display screen without a traditional monitor in sight. First, let’s look at what’s being discussed.
So, the game board is a 4×5 matrix of hexagons, that in main play can show the letter slide, a blue fill, a white fill and a gold fill, with black acting as an absence, with a suitably coloured surround. The general quality of image and the nature of the lighting suggest that this is in fact an array of slide projectors, independently controlled and automated at the lighting console to bring the relevant slides in. Studio 2 Television has a YouTube video showing a selection of these, with ‘light tight’ black masking to permit overlapping projections without bleedthrough. As mentioned in the comments, the board itself had a series of hexagonal features within it that assisted with the effect (and seemingly an extra row left unused, or at least masked off on the presentation side). In addition within the slide collection is an apparent representation of the Central logo (or a striped circle at least), for use in the Gold Run.
The brilliant Dirty Feed blog written by Central region native John Hoare contains a scan of the 1989 annual suggesting that 20 slide carousels need to be overhauled after a run of 6 ‘full games’ (18 regular rounds, or more importantly 6 Gold Runs), which suggest that each segment has a projector devoted to the main display, but the speed of slide change is not sufficient to allow these to handle the solid hexagons indicating game play. Realistically, each segment in fact has two projectors focused on it, with quick cutting between the two to make the game work. For simplicity, the material for one projector pair for a single game is shown below
The ‘main projector’ fades between off and full brightness when a letter is selected, with the secondary projector totally off, but cycling to the relevant colour slide as a contestant buzzes in. If the answer is correct, the main projector is shut off, the secondary is turned on and the segment instantly changes colour. It appears at this point the main projector is switched to gold if need be for the round end sequence, as transitions would be too slow otherwise. When a potential victory sequence is spotted, a simple power cycle is enough to show it.
If a gold run is called for, the surround is changed to its alternate palette, and the main board carousels move to that particular Gold Run board. This is a rather simpler state for the secondary projectors, as these can be set directly to gold. If a question is right, the secondary projector is set to on with the main one turned off, if wrong, both are turned off to leave the segment black. Seems simple enough, but even then problems can occur as this clip from the US Blockbusters series shows.
It seems in this case that a power spike caused the wrong projectors to come on with their alignment slides on. All the more remarkable that the contestant could plot a path, really.