1 Introduction
32 5977B Series MSD Operating Manual
To Replace the Primary Fuses
Materials needed
• Fuse, T12.5A, 250 V (2110-1398) – 2 required
• Screwdriver, flat-blade (8730-0002)
The most likely cause of primary fuse failure is a problem with the foreline
pump. If the primary fuses in your MSD fail, check the foreline pump.
Procedure
1 Vent the MSD, and unplug the power cord from the electrical outlet.
If one of the primary fuses has failed, the MSD will already be off, but for
safety, switch off the MSD and unplug the power cord. It is not necessary to
allow air into the analyzer chamber.
2 Turn one of the fuse holders counterclockwise until it pops out. The fuse
holders are spring loaded. (See Figure 2 on page 33.)
3 Remove the old fuse from the fuse holder.
4 Install a new fuse in the fuse holder.
5 Reinstall the fuse holder.
Never replace the primary fuses while the MSD is connected to a power source.
If you are using hydrogen as a carrier gas or for the JetClean system, the hydrogen
gas flow must be off before turning off the MSD power. If the foreline pump is off,
hydrogen will accumulate in the MSD and an explosion may occur. Read “Hydrogen
Safety” on page 23 before operating the MSD with hydrogen gas.