Lake Shore Cryotronics Measure Ready M91 FastHall, User Manual

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184 Appendix A: MeasureReady™ FastHall™ Station
MeasureReady™ M91 FastHall™ Measurement Controller
A.7 Service
Reference This section provides information for line voltage selection, electrical ground
connection, ESD and safety information.
A.7.1 Line Voltage
Selection The instrument chassis and cabinets are grounded for safety. The safety ground
provides a true ground path for electrical circuitry and, in the event of internal
electrical faults such as shorts, it carries the entire fault current to ground to protect
users from electrical shock. If the earth ground connection is impaired, render the
system inoperative and secure it against any unintended operation. The ground
connection is likely impaired if the equipment exhibits any of these conditions:
D
Shows visible damage
D
Fails to perform the intended measurement
D
Has been subjected to prolonged storage under unfavorable conditions
D
Has been subjected to severe transport stresses
D
Has been serviced by unqualified personnel
Do not use an apparatus exhibiting any of these conditions until qualified service
personnel verify its safety.
When the instrument or equipment is removed from the system for service, make a
note of its line voltage setting. When the item is returned, verify its line voltage
setting with the voltage on the note before incorporating it into the system.
When the system is moved to a new location, before connecting the input power cord,
verify that the system voltage setting is the same as the facility line voltage. When it’s
necessary, adjust each instrument in the console to the correct voltage. Read each
instrument manual provided for detail on voltage adjustment.
A.7.2 Electrical Ground
Connection All instrument cases are grounded to the ground lead of the power distribution strip
through its input power cable.
There is a safety ground cable built into the 22-pin connector on the multifunction
cable for connection to the outer case of the sample insert to the instrument console
chassis. Low impedance connections are maintained for safety purposes. This safety
ground connection should be reestablished and maintained if any service is
performed on the cable or measurement insert.
A protective earth terminal is present on the electronic console’s rear rack mounting rail.
Do not disturb or remove any wires connected to this terminal.
A.7.3 Electrostatic
Discharge Electrostatic Discharge (ESD) may damage electronic parts, assemblies, and equip-
ment. ESD is a transfer of electrostatic charge between bodies at different electro-
static potentials caused by direct contact or induced by an electrostatic field. The
low-energy source that most commonly destroys Electrostatic Discharge sensitive
devices is the human body, which generates and retains static electricity. Simply
walking across a carpet in low humidity may generate up to 35,000 V of
static electricity.
Current technology trends toward greater complexity, increased packaging density,
and thinner dielectrics between active elements, which results in electronic devices
with even more ESD sensitivity. Some electronic parts are more ESD sensitive than
others. ESD levels of only a few hundred volts may damage electronic components
such as semiconductors, thick and thin film resistors, and piezoelectric crystals
during testing, handling, repair, or assembly. Discharge voltages below 4000 V cannot
be seen, felt, or heard.