Duffy was a fairly large concern in northern New Jersey that is no
longer in business.  Many of the units they sold were actually made
by Aeolian.  I've encountered a few players with the Duffy sticker
that were modified into coin-operated units.  Usually this involved
a rather noisy solenoid, a couple of relays, auto-rewind and
auto-shut-off devices and a coin-drop mechanism.

Since the transmission solenoid was way more powerful than what was
actually required to do the job, the linkage and the transmission in
these units are usually damaged to some degree.  Also, the relays,
which are switching the 120 VAC on and off, usually have burned or
charred contacts.

Based on my experience as an electronics technician, I believe it
would have been impossible for Duffy to get a UL listing for their
coin-op modifications.  The wiring is usually 'helter-skelter' and
there is no overload protection (fuses).  To my knowledge, Duffy never
produced a schematic which shows how the system was wired.  This makes
trouble-shooting the system a bit difficult until after you've
encountered one or two of them.  Overall, I consider the modification
poorly designed at best and a potential fire-hazard at worst.

Musically,

John A. Tuttle