by
lmh » Mon Jul 12, 2021 1:12 pm
Years since I've looked at one, but these autosamplers had a strange double-piston syringe thing, and it's utterly vital it knows where the plunger is (because the volume moved depends on whether it's driving the outer or inner syringe piston, and that depends on how far it's driven it). I'm guessing it's trying to look for a flag on the syringe drive, so that it knows when it's reached the end of the movement of the syringe. Is the syringe drive actually working? Is it slipping? I remember these being very vulnerable to belt-slippage, and to getting dirty, which then means it gradually loses position. If it's moving right up to the end but apparently not detecting the flag, maybe the flag detecting thingy has gone wrong, but I can't remember what it looks like on a Surveyor autosampler. But seriously, the best thing to do is get a new autosampler. The Surveyor autosampler was possibly the worst autosampler ever made for any LC system, ever. It's very probably the worst LC unit ever made, combining double-digit carry-over values with an uncanny knack of losing the sample altogether. The Surveyor PDA, on the other hand, was a beautiful detector.