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MMD > Archives > June 2014 > 2014.06.18 > 07Prev  Next

Repairing On/Off Switch for Modern Aeolian Player
By John A. Tuttle

Hi All,  Regarding the problem with the 1974 Aeolian Duo/Art shutting
off when the system goes into Rewind, the most likely problem is the
absence of the bleed inside the shut-off pneumatic.

The way Aeolian built that model requires that there be a small
needle-size bleed inside the bellows which limits the air flow.  This
is done so that when the system goes into Rewind, the vacuum that is
used for shifting the transmission _and_ for turning off the Cherry
(power) micro-switch is impeded, which radically slows the operation
of the shut-off bellows.

Then, when the roll finishes rewinding, the same (rewind) valve is
triggered again, but this time there is time to collapse the shut-off
bellows and the system shuts down.  (The annoying factor is that the
roll keeps spinning in rewind until the shut-off bellows finally
collapses enough to shut off the power.  And, if the shut-off bellows
is leaking slightly, it never develops enough power to shut off the
switch.  So, the owner has to pull the switch out to turn everything

Maybe I can clarify that a little.  Since the Rewind perforation is
only present for a very short period of time when the system goes into
rewind, the shut-off bellows doesn't have enough time to close fully
and turn off the power.

What sometimes happens is that a well-meaning technician will remove
the paper bleed inside the shut-off bellows, thinking that it will
perform better -- or have more power to turn off an aging switch.
As a result, the bellows works so quickly that it shuts off the power
when the system goes into Rewind, making it necessary for the owner
to turn the power back on.

The solution: Rebuild the shut-off bellows and make sure the vacuum
port going into the bellows is covered by a piece (a dot) of paper
with a bleed-size hole.

John A Tuttle
Brick, New Jersey, USA

(Message sent Wed 18 Jun 2014, 20:53:15 GMT, from time zone GMT-0400.)

Key Words in Subject:  Aeolian, Modern, On/Off, Player, Repairing, Switch

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