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MMD > Archives > March 2012 > 2012.03.21 > 06Prev  Next

Operation of Story & Clark Classic Console Play
By John A. Tuttle

Hi All,  Tony Marsico writes, "There must be some other interaction
between the lever (Spool Fill Arm) and the rewind in this Story and
Clark" (MMDigest 12.03.19), and he's correct.

Unlike all other pneumatically operated and electro-pneumatically
operated players with an Auto Shut-off sequence, the Story & Clark 
(and the Universal, its predecessor) has what I call an automatic 
"Play Reset" sequence the follows the Rewind and Auto Shut-Off
sequences.  This sequence is purely electronic in nature.  It is not 
a mechanical operation.

As it says in the service manual, the purpose of the Spool Fill Switch
is to "Disable the reroll circuit so that the piano does not reroll
when first started."  While this function is not fully explained in 
the manual, there is a time-delay circuit on the circuit board which is
'flipped' into operation at the same time that the negative voltage to
the drive motor is turned 'off' and the voltage to the vacuum pump is
turned 'off.' Outwardly, those two operations appear to be the only
function of the Spool Fill Switch.  The time-delay circuitry stays in
the 'on' mode for a period of time (approx. 5-7 seconds), as determined
by the setting of R27, until it gets an 'over-ride' signal from the
Spool Fill Switch, which 'flips' the time-delay circuit 'off.'
Obviously, if this did not happen, the circuit would be permanently
'locked' in the Forward Roll mode, and the system could not go into
Reroll when triggered by the Auto Rewind Pneumatic.

Although it is not clear in the wiring diagram, I've been told that the
Play Pneumatic switch and the Spool Fill Switch must both be 'on' for
the system to remain in Forward Roll after the Time-Delay has 'timed
out.'  In other words, if one of those two switches did not come 'on'
during the time-delay period, the drive motor would simply stop, and
the system would go into auto-reroll.  Therefore, I have come to the
conclusion that the 'fail-safe' mode of the system is to rewind the
roll and shut off if the forward roll sequence does not function
properly.  I have personally experienced this problem, which left me
scratching my head and wondering why the system rewound the roll and
shut off power when nothing had obviously changed mechanically
speaking.  It turned out to be a defective Play switch.

See wiring diagrams at:

In closing, the service manual has a relatively good Troubleshooting
Guide that covers a wide range of possible problems.  Sadly, after all
of the switches and pneumatics have been eliminated as the cause of a
problem, the final words are "the circuit board is at fault" or "the
circuit board is probably at fault."  (Naturally, there are other
possible problems that don't involve the circuit board.)  However, in
defense of the S&C players, I've only had to change two boards in all
the years they've been in existence. The manual is available at:

John A. Tuttle
Brick, NJ

(Message sent Wed 21 Mar 2012, 05:39:48 GMT, from time zone GMT-0400.)

Key Words in Subject:  Clark, Classic, Console, Operation, Play, Story

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