Sony GY-2120WD Maintenance Manual page 335

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6-2. Description of Commands
In case of NG:
When the threading ring operation is detective:
. Confirm that there is no mechanical abnormality.
. Check the threading motor drive circuit (DR-327 board or MS-54 board).
. Check the threading motor.
When the threading ring is in the thread end/unthread end state but message "............" is displayed:
. Check the thread end sensor or unthread end sensor (TR-79 board).
. Check the sensor input port of a CPU (MA-83 board).
Threading ring
Unthreading end sensor
Theading motor
Threading end sensor
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6-111
GY-2120WD/WS