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NuTone Intercom Photo Gallery > NuTone Stereo Music Intercom Model SM428 > NuTone SM428 amplifier board

NuTone SM428 amplifier board

This is 1 of the 2 amplifier modules from the SM428.  Both modules are identical and they can be installed in either position on the main board.

Mounted inside the aluminum heat sink is the single amplifier IC.  Each amplifier module is rated for 6 watts of output.  The amplifier IC was also used in the IMA406 system and was commonly used in many portable and automotive radios in those days.

These IC's have become difficult to find and the last time I needed to purchase some, I found them from a supplier in England at a cost of $18.00 each.