The NuTone Model 470 Amplifier was originally introduced in the early 1960's.
It's basic design of the 470 is based on the amplifier and intercom circuits of the 2561 / 2562, however it has been greatly simplified. It does not have a gain control for the amplifier output and there isn't provision for an auxiliary audio (music) input. The model 470 was simply design as a communication amplifier.
It was always called the "Commu-Ni-Com" Intercom System, even through its last version - the IMA516
This Model 470 amplifier was manufactured in February 1972, which makes it a 2nd generation 470.
It's simple design makes it very long lasting and this will be the very first repair of this particular amplifier.
While the Model 470 is a completely Solid-State device, it only contains 4 transistors and a single diode.