To Replace The Primary Fuses - HP 5973 Hardware Manual

To replace the primary fuses

Materials needed:
Fuse, T8 A, 250 V (2110-0969) – 2 required
Screwdriver, flat-blade (8730-0002)
The most likely cause of failure of the primary fuses is a problem with the foreline
pump. If the primary fuses in your MSD fail, check the foreline pump.
1 Switch off 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
you should switch off the MSD and unplug the power cord.
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If a fuse failure turns off the MSD, wait at least 30 minutes before venting the instrument.
Venting sooner could cause a diffusion pump to backstream or could damage a
turbomolecular pump.
2 Vent the vacuum manifold by opening the vent valve knob.
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3 Turn one of the fuse holders counterclockwise until it pops out.
The fuse holders are spring loaded.
4 Remove the old fuse from the fuse holder.
5 Install a new fuse in the fuse holder.
6 Reinstall the fuse holder.
Maintaining the MSD
4
To replace the primary fuses
181