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M7484A
OPERATION AND CHECKOUT
OPERATION
The M7484A is a fixed 90° stroke nonspring return
motor. An internal sensing circuit incorporates a feedback
potentiometer in a bridge circuit. The feedback potenti-
ometer circuit output is proportional to the mechanical
shaft position. An 8 Vdc power source from the BCS 7700
is required for circuit operation.
The M7484A is driven by applying 24 Vac to either the
open or closed motor coils. Position control is accom-
plished by using the BCS 7700 to monitor the feedback
potentiometer circuit and energize or de-energize the
drive coil(s) to achieve the required position.
CHECKOUT
After installation and linkage adjustment, check the
entire motor and control hookup to prove that:
— the motor properly operates the damper or valve.
— the motor properly responds to the BCS 7700.
Inspect the motor, linkage and valve or damper to
determine that all mechanical connections are correct and
secure. Be sure the pushrod does not extend more than a
few inches past the ball joints. Check to be sure there is
Home and Building Control
Honeywell Inc.
1985 Douglas Drive North
Golden Valley, Minnesota 55422
Printed in U.S.A.
Operation and Checkout
Home and Building Control
Honeywell Limited—Honeywell Limitée
740 Ellesmere Road
Scarborough, Ontario
M1P 2V9
adequate clearance for the linkage to move through its
stroke without binding or striking other objects.
The M7484A is shipped in the fully closed position (the
limit of counterclockwise rotation as viewed from the
power end of the motor).
To check operation of the M7484A:
1. Place the BCS 7700 in Standby; open the Burner
Switch.
2. Place the RUN/TEST Switch in the TEST position.
3. Place the BCS 7700 in the Manual mode using the
AUTO/MANUAL key of the Keyboard and Display Mod-
ule.
4. Place the cursor in the Keyboard and Display Mod-
ule Liquid Crystal Display beneath % Rate, using the (<)
key.
5. Using the Keyboard and Display Module (+ or - )
keys, under manual control, drive the motor through its
entire stroke to assure the motor is responding to the BCS
7700 commands.
6. While manually adjusting the motor position, ob-
serve the position of the motor, as displayed on the
Keyboard and Display Module, to assure proper operation
of the feedback potentiometer circuit.
Helping You Control Your World
QUALITY IS
KEY
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