216 5977B Series MSD Troubleshooting and Maintenance Manual
8 Electronics
• Generates ±280 VDC (nominal) power for main board lens amplifiers and
side board DC amplifiers.
• Supplies and controls the power for the ion source and quadrupole (mass
filter) heaters.
• Provides 24 VDC power for the cooling fans.
Signal amplifier board
The signal amplifier board amplifies the output of the detector. It produces an
output voltage of 0 to 10 V DC, proportional to the logarithm of the input
current of 3 picoamps to 50 microamps.
An analog-to-digital converter converts the amplifier output voltage to digital
information. The LAN/MSD control card converts the data into abundance
counts proportional to the detector signal current.
Lens driver board for HES
The lens driver board provides the lens voltages for the extractor, post
extractor 1, and post extractor 2 lenses.
AC board
The AC board is mounted on the opposite side of the electronics panel from
the LAN/MSD control card. The AC board is also sometimes called the power
distribution/vacuum control board. It performs these functions:
• Provides input voltage transparency for the MSD.
• Distributes AC line power to the AC/DC power supply, the foreline pump,
and the turbo pump controller.
• Turns the calibration valve on or off as directed by the main board.
• Provides the voltage for the calibration valve.
• Provides a logic interface to turbo controller.
• Controls the diffusion pump:
• Controls the foreline gauge.
• Turns on the diffusion pump once the foreline pressure is low enough, as
directed by the main board.
• Regulates the AC power to the diffusion pump heater.
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