Agilent Technologies 5975T LTM GC/MSD, Troubleshooting And Maintenance Manual

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Electronics
14
Troubleshooting and Maintenance Guide 219
Electronics Module
Most of the electronics in the MSD are contained in the
electronics module. The whole electronics module can be
replaced, if necessary, by your Agilent Technologies service
representative.
The electronics module contains:
• Main board
• Signal amplifier board
• LAN/MS control card
• AC board (power distribution / vacuum control board)
•
Low voltage (AC-DC) MSD power supply
• High voltage (HED) power supply
• Toroid transformer assembly
MSD main board
The MSD main board is mounted on the outer side of the MSD
electronics module. The MSD main board performs these
functions:
• Receives and decodes digital instructions from the LAN/MS
control card.
• Sends digital information to the LAN/MS control card.
• Generates voltages for the ion source lenses.
• Generates control signals for filament selection, filament
emission current, and electron energy. Generates control
signals for quadrupole RF drive, quad frequency adjustment,
DC polarity selection, and all detector voltages.
• Performs analog-to-digital conversion for the Direct signal,
ion source and mass filter temperature signals, and foreline
pressure or turbo pump speed signal.
• Monitors the signals from the vacuum system and fans and
the filament status, HV fault and RF fault signals from the
side board. Activates the shutdown line when the analyzer
electronics must be disabled.
• Generates the control signals (on and off) used by the AC
board for the high vacuum pump and calibration valve.
• Generates ±280 VDC (nominal) power for main board lens
amplifiers and side board DC amplifiers.