Chromatography Forum

I have a problem with my Waters 717 autosampler carousel, the carousel can be picked up, but could not be spun with some noise when the motor try to spin, the error message shows "could not position the carousel". Any ideas? Thanks!

Could be a couple of things: 1. A bad motor; or 2. Lots of crud built up in the sample compartment & on the bottom of the carrousel. (Has your seal pack been leaking lately?). Assuming the latter, clean the sample compartment thoroughly and try again.

Thank you for replying! I changed a carousel, it is still as before. Meanwhile, seal pak didnot leak.

Anybody has any ideas? Thank you a lot......

The carriage belt did either rip or fall off. Open the case and check between the carriage motor and the axis for the tray.

The problem was fixed, when I took out the driving part, and totally clean the lifting shaft. Thank you guys for your kind reply and attention. Good luck!

I think that I may be having the same issue. The carousel is picked up by the arm but when it tries to home it makes a grinding/ratcheting sound and then displays the error "could not position vial."

When you experienced this problem, how did you access the compartment and which components did you clean.

I have already thoroughly cleaned the sample bay and carousel.

Thanks,

I'll write up what I remember of the removal and replacement of the carousel drive assembly. I had to do this about a year ago when the drive on my 717 failed, apparently in the same manner as yours (note, the photos below were taken of the 717 that I have for parts, don't mind the missing screws, foil on the battery, etc...):

1. Turn off and unplug the instrument. I don't want you to electrocute yourself.

2. Remove the cover: First remove the plastic cover over the syringe, then unscrew the torx screw you see at the top center. Pull the instrument cover straight back a few cm, then pull up and off at the rear.

3. Locate the carousel drive and electrical connectors on the PC board. The carousel drive is the big bit in the center of the chassis with two Vexta stepper motors mounted upon it.



There are three connectors on the PC board - one for each of the stepper motors and one for the carousel position sensor flags. Ground yourself to dissipate any static electricity then carefully undo the connectors from the PC board.





4. Locate the four Torx head screws holding the carousel drive to the chassis and carefully remove them. It might be easier to unbolt the power supply from the rear of the instrument and slide it backwards out of the way in order to access the screws closest to it. You don't have to disconnect it because you only need to move it a few cm.

You see the rearmost hole for one of the screws in the center of this photo; the power supply can be seen on the left side of the photo and there is another screw adjacent to that. There are another two at the front of the assembly.



5. Once you have all of the screws removed, carefully lift the assembly from the chassis and clean or replace it as needed.

6. Reassembly is (of course) the reverse.

7. I believe that if you move the motor shaft to raise or lower the carousel arm, you will need to reinstall it such that the position flag blocks the top sensor, thus "orienting" the instrument to its position. If you don't do this, I believe there will be an initialization error upon startup. It's not a great photo, but the upper and lower position sensors are at the end of the wire bundle shown below:



I hope this is helpful. Please note that I am not and have never been a Waters service engineer. I'm just a DIY chromatographer (who is now doing product development and process optimization for a living) - go figure.

If you have any questions or if anyone has any suggestions or corrections, please post them here.

Cheers!