4 Maintaining the MSD
97
Many parts of the MSD carry high voltages that are
potentially dangerous
Whenever the MSD is plugged in, even if the power switch is off, potentially
dangerous voltage (120 V ac or 200/240 V ac) exists on:
• The wiring and fuses between where the power cord enters the
instrument and the power switch
When the power switch is on, potentially dangerous voltages exist on:
• Electronic circuit boards
• Toroidal transformer
• Turbomolecular pump controller
• Wires and cables between these boards
• Wires and cables between these boards and the connectors on the back
panel of the MSD
• Some connectors on the back panel (for example, the foreline power
receptacle)
Normally, all of these parts are shielded by safety covers. As long as the
safety covers are in place, it should be difficult to accidentally make contact
with dangerous voltages.
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