General Maintenance 4
Troubleshooting and Maintenance Manual 69
Tools, spare parts, and supplies
Some of the required tools, spare parts, and supplies are included in the GC 
shipping kit, MS shipping kit, or MS tool kit. You must supply others yourself. 
Each maintenance procedure includes a required materials list.
High voltage precautions
When the MS is plugged in, even if the power switch is off, dangerous voltage 
(200/240 VAC) exists on the wiring and fuses between where the power cord 
enters the instrument and the power switch.
When the power switch is on, dangerous voltages exist on:
• Electronic circuit boards
• Toroidal transformer
• Wires and cables between these boards
• Wires and cables between these boards and the connectors on the back 
panel of the MS
• 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.
Some procedures in this chapter require access to the inside of the MS while 
the power switch is on. Do not remove any of the electronics safety covers in 
any of these procedures. To reduce the risk of electric shock, follow the 
procedures carefully.
Dangerous temperatures
Many parts in the MS operate at, or reach, temperatures high enough to cause 
serious burns. These parts include, but are not limited to:
• GC/MS interface
• Analyzer parts
Perform no maintenance with the MS turned on or plugged into its power source 
unless you are instructed to do so by one of the procedures in this chapter.