Specifications

188 5975 Series MSD Troubleshooting and Maintenance Manual
6 Vacuum System
Check the condition and level of the diffusion pump fluid through the window
(sight glass) near the base of the front of the pump. See Figure 40. If the level
drops below the appropriate marker (there are separate ranges for hot and
cold conditions) or if the fluid turns dark brown or black, replace the fluid.
Otherwise, replace the fluid once a year.
Changes at 170 °C rising; 140 °C
falling
365 °C rising
Function Keeps analyzer turned
off until the pump is hot
enough to for adequate
vacuum. Prevents
analyzer damage
Shuts off diffusion pump
and analyzer if the pump
overheats. Prevents
damage to the pump and
analyzer.
Message The high vacuum pump
is not ready
Difficulty with the high
vacuum pump
What it means Normal during
pumpdown
Always indicates a
problem
What to do Wait for pump to heat up Check the level and
conditions of the fluid.
Make sure pump is cool,
and power-cycle MSD to
reset.
Table 10 Diffusion pump thermal switches (continued)