2000 MS Hardware Maintenance
12
Functional Description
The electronics section fan draws air from the back, and blows it across the
SAP/WAVE and power boards in the electronics compartment. Hot air from the
GC oven does not affect the MS as long as the system is at least six inches from
a wall. The power board supplies power to the electronics compartment fan.
Diffusion Pump System
The GC/MS Diffusion pump system has three cooling zones, each with its own
fan mounted in the rear of the instrument.
Cooling Zones
Zone 1
is the upper part of the analyzer compartment. Its purpose is to provide
forced air-cooling for the Peltier baffle’s heat sink. It also provides cooling for the
manifold electronics. The upper fan on the rear panel pulls air in through the
front of the instrument. The air is drawn over the manifold electronics, ducted
over the Peltier baffle’s heat sink, and expelled through the rear of the
instrument. The diffusion pump controller monitors operation of this fan. Fan
failure will trigger a system shutdown.
CAUTION
The Peltier Baffle ducting must be left in position at all times, or the Peltier
baffle will overheat allowing back streaming pump vapor to contaminate the
analyzer.
Zone 2
is the electronics compartment, diffusion pump controller, and RF
generator board. Its purpose is to cool the majority of the instrument’s printed
circuit boards. The mid level fan on the rear panel pulls air in from two directions.
The primary cooling air supply is pulled in through the front of the instrument,
over the power board and SAP/Wave board, and expelled through the rear of the
instrument. A secondary air supply is pulled in through the left side panel, ducted
over the RF generator board, the diffusion pump controller, and then merges with
the primary airflow.
