# Ulvac G-100 Used by many [[JEOL]] Electron Microscopes, including: - [[JSM 5600 - JEOL W SEM]] ## Failure modes First thing to go is usually the main shaft seal. If you have a puddle of oil under your pump, this is likely the culprit. Sometime after starting to leak oil, the pump will usually also experience performance degradation. This is progressive process right up until it isn't. It will fail slowly at first, then quickly. At that point is usually when the SEM stops pumping down. ## Rebuild See: [[Ulvac G100 rotary vacuum pump rebuild]] ## Why are there 2 cables? One is for power, one is to detect if the pump is no longer working. Thats the intention at least. Whats really going on though is the second cable is only capable of detecting if the pump is receiving power OR if the pump's internal thermal switch has gone open circuit.