Tandon TM100-1 Operating And Service Manual page 42

SPINDLE MOTOR CONTROL CIRCUIT
The Spindle Motor Enable signal is input via Pin
7 of the servo circuit board to gate the spindle
motor current (Figure 4-10). This current is con­
trolled by an integrated regulator circuit when
the spindle motor is enabled. The potentiator
provides an adjustable D. C. voltage reference to
the regulator circuit for spindle speed adjust­
ment. The tachometer signal provides feedback
from the motor via Pins 1 and 2 of the servo cir­
cuit board to maintain a constant speed of 300
RPM. This signal is 12 volts A. C.
4-12
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