The end of an era, the final ever Bell Colt - the Mk III. Almost lost inside the now cavernous Colt cabinet, the Mk III circuit board is tiny compared to the chassis used in pretty much every other colt produced over the previous 25 or so years.
Early models had a grey back panel with the previous style chassis tag riveted to the outside, although this was replaced with a patterned brown panel with a paper serial number label glued on at some point in the production.
Its worth noting that this is the only model released to ever have both 'Bell' and 'Colt' on the dial glass (most just had 'Bell', although the odd one had 'Colt'), and the only model to shift the dial pointer to be vertical, moving left to right instead of up and down. There were at least two different versions of the dial glass for this model as seen below, with the early version shown on the left.
Bell Colts ran from 1951 through until 1980 - the longest running model of NZ built domestic radio. It saw many different engineering changes over the years, and the last few models dropped valves in favour of new transistor technology. There is considerable information on the main Colt page about this Kiwi icon.
The radios in this series are:
Frequency Bands: 1
Chassis Notes(most schematics can be clicked to download a full size version)
The chassis has finally been replaced with a printed circuit board, and the dial lights with miniature grain-of-wheat lamps which are quite difficult to replace and almost impossible to find.
Schematic might also work for MKII (Its unsure what Series II on the schematic means)
Another scan of this schematic that may provide more (or different) details