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- Posts: 102
- Joined: Tue Oct 06, 2020 10:01 pm
- Location: Australia
It powered on as expected, but initially the roughing pump only kicked in for about 10 seconds before switching itself off. We power cycled the instrument again and this time the roughing pump stayed on continuously, but the vacuum readouts in MSD Trap Control stayed at 6.94e+00 for the foreline pressure and 4.44e+01 for the high vac pressure. These numbers varied a little over time, but didn't fall to their expected values.
I loaded up the onboard diagnostics (via the http interface) and it's reading that the turbos have reached full speed, despite the foreline vacuum being nowhere near low enough. This has got me a bit worried... I can hear them spinning up, and although I'm not familiar with the trap version of this instrument, to my ears they sound louder than they should be. No different to a normal turbo sound, just louder.
All of the vacuum system tests except for the High Vacuum Pressure and Ready Vacuum System are passed, as have all the other diagnostics except for those that can't run because the vacuum is too high.
So, any ideas why it can't pump down? I have tried switching the pump with the one from our old Waters ZMD, but no improvement. There don't appear to be any obvious points of leakage along the chamber. Next step will be to check chamber seals, etc. but this is a bit involved. I am also worried that maybe the Pirani gauge has had it and is giving faulty readbacks - maybe explaining why it's reading high but the turbos are spinning up normally.
Another bit of info - the instrument has been powered down for the past 2-5 years. I know turbos don't like being disused for a while, but I've previously had no issues spinning up turbos that have been out of action for a couple of years.
The issue of the roughing pump not staying on also recurs every second or third power-cycle, which is also odd.
Any suggestions would be most appreciated.