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Troubleshooting the MSD
3
General symptoms
Fan for the high vacuum pump is not operating
This refers to a condition where the MSD is on (at least the foreline pump is
operating) but the fan for the high vacuum pump is not working. You can deter-
mine this by listening or by putting your hand next to the ventilation slots on the
front of the instrument. You should be able to feel air being pulled into the MSD.
• Disconnected fan cable
• Disconnected high vacuum signal cable (never connect or disconnect
this cable while the MSD is on)
• Malfunctioning fan
MSD is on but the status LEDs are all blinking
This is normal when the MSD is initially turned on. The status LEDs blink until the
data system software is started or the pumpdown cycle is initiated. The data sys-
tem then downloads the instrument control software to the HP-IB/MS control
card. When this occurs, the status LEDs will all light for a few seconds and then
begin to operate normally, leaving the power LED on and the others off. If the sta-
tus LEDs do not stop blinking, or if the status LEDs are all blinking at a time other
than startup, one of the following may be the cause:
• Temporary power failure interrupted communications
• Bad connection between the MSD and the data system
• Software malfunction
• MSD electronics are not working correctly
If the status LEDs continue to blink there will usually also be an error message in
the MSD ChemStation software.
MSD turns on but then the foreline pump shuts off
MSDs with serial number XX820XXXXX and above will shut down both the fore-
line pump and the high vacuum pump if the system fails to pump down correctly.
This is usually because of a large air leak: either the sideplate has not sealed cor-
rectly or the vent valve is still open. This feature helps prevent the foreline pump
from sucking air through the system, which can damage the analyzer and pump.
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