Model 8703 System 23
CAUTION
The Picomotor will be damaged if the PULSE RETURN and
PULSE OUT connections are reversed. Check with New Focus if
you have any questions about Picomotor wiring when using
J103.
Also, be careful when connecting a scope probe to the unit
output. The probe clip is connected to the scope chassis
ground. If the probe clip is accidentally connected to the 8712
Pulse Output, the output stage may be damaged.
4.2.1 Isolation
The system board includes some circuitry to isolate the 8712 from the
Picomotor cabling. L102 and L101 ferrite beads increase the impedance to a
few hundred Ohms at high frequencies. D111 and D110 TVS diodes shunt
high voltage pulses to the frame ground terminal PX600. The frame ground is
also connected to the 8712 to ground the internal filter-T networks.
The pulse output, pulse return, and frame traces are low inductance. Pulse
output and return carry 2 A transient currents and must be tightly coupled.
The frame connection is also low inductance; it carries high current with
wide bandwidth when ESD events occur. The connection to system frame
ground is made with screw terminal PX600. Use a short wire or metal
binding post to connect PX600 to the equipment frame.
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