Functional Description
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___________________________________________________________________ MS Detector
_______________________ Finnigan LTQ Hardware Manual _____________________
2-33
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power to all components of the MS detector other than the fans and vacuum
system. In the Electronics Normal position power is supplied to all
components of the MS detector.
The Interlock PCB, which resides in the Power Module, receives 220 V ac
from after the electronics service switch (called service 220 V ac) and
+24 V dc from PS2 power supply via the Power/Signal Distribution PCB. If
the safety interlock switch on the API source is closed, then the Interlock PCB
distributes 220 V ac to the APCI vaporizer heater and +24 V dc (called
int24 V dc) to the Power/Signal Distribution PCB, which distributes it
to the 300 V power supply, 8 KV power supply, and the conversion
dynode/electron multiplier power supply.
The Power/Signal Distribution PCB receives 220 V ac and service 220 V ac
from the Power Module. The Power/Signal Distribution PCB distributes the
220 V ac to power supply PS2 and the service 220 V ac to power supply PS1.
It then distributes the power produced by PS1 and PS2 to other power
supplies, PCBs, turbomolecular pump, vent valve, and fans. The
Power/Signal Distribution PCB also receives the int24 V dc from the
Interlock PCB and distributes it to the 300 V power supply, the 8 KV power
supply, and the conversion dynode/electron multiplier power supply.
Power supply PS1 pr5 V dc,
±
15 V dc for analog and digital circuits
and +60 V dc for the heater that heats the ion transfer capillary.
Power supply PS2 pr24 V dc for the turbomolecular pump, fans, vent
valve, divert/inject valve, syringe pump, 8 KV power supply, conversion
dynode/electron multiplier power supply, Main RF PCB, and Analog PCB. It
also pr36 V dc and -28 V dc that is used for RF generation for the ion
guides and mass analyzer.
The 300 V power supply provides the
±
300 V dc and
±
150 V dc that is used
by the Analog PCB to produce lens and dc offset voltages for the ion source
interface, ion optics, and mass analyzer.
The Source PCB distributes power to the ion gauge, divert/inject valve,
syringe pump, and nitrogen and helium gas valves.
The 8 kV power supply delivers voltage to either the ESI needle in the ESI
mode, or the corona discharge needle in the APCI mode. Typical operating
voltages range between ±3 to ±6 kV. In the ESI mode, the voltage is regulated,
whereas in the APCI mode, the current is regulated.
The conversion dynode / electron multiplier power supply provides
±
15 kV
to the conversion dynodes and 0 to –2.5 KV to the electron multipliers in the
ion detection system.
Note. For emergency shutoff of all power to the MS detector, place the main
power circuit breaker switch in the Off (O) position. Do not use the
electronics service switch to remove power to the system in an emergency.
