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NuTone Intercom Photo Gallery > NuTone Stereo Music Intercom Model SM428 > NuTone SM428 amplifier boards and preamp board

NuTone SM428 amplifier boards and preamp board

Here's a close up view of the amplifier modules.  These are a fairly simple design using a single amplifier IC that is mounted inside it's rather large heat sink.  Each amplifier is rated at 6 watts per channel.

There are 2 variations of amplifier modules (called out as "early" and "late" production) in the service manual.  The difference haveto do with the supporting componets on the amplifier module.

The red arrow points to the Intercom - Pre-amp board.