PDA detector troubleshooting

<p><span>Hi!!</span></p><p></p><p><span>The instrument (Acquity UPLC) was off and we turned on. The detector is giving me an error that says: <strong>Shutter assembly could not home. Have this happened to anyone before? What can I do?</strong></span></p><p></p><p><span>I checked the help topics and it says that I should run the shutter diagnostic test, <strong>how can I run that? </strong></span></p><p></p><p></p><p><span>Thanks a lot in advance!!!</span></p>


  • Dear Deleon,

    I have this message on my system, from time to time. Service in not 100% sure what is reason for that (bubbles in detector cell could be...), but I have a cure. Ignore the message, continue with flushing the system (and detector too), and after a while reset your PDA. If the problem persist, flush your PDA with 100% ACN for ten minutes and reset the detector. One of these will help for sure.



  • deleon

    Thanks a lot for your answer and have a great day!!


  • lizh


    The error message “shutter assembly could not home" can be caused by several common reasons. Note, the Shutter position is one position on the Filter wheel assembly, which has other positions that can be located. Here is a list of suggestions direct from Global Service Support.

    (1) First of all the light transmission though the optics depends upon good light transmission through the flow cell. If the flow cell is dirty or has a air bubble in it then we do not see the difference in energy as the filter wheel move to its

    different positions.(it cannot tell light from dark and throws up the error) due to the loss of transmitted energy through the flow cell. We would recommend the user make sure the flow cell is clean and free of any air bubbles, (which is exactly what Milos very correctly recommended). Also make sure the solvent is fresh, filtered, clean and flowing before turning on the detector.

    If you have access to the appropriate Shunt cell tool, which is a cell that substitutes for the working flow cell and does not have fluid connections, but will transmit the light from the lamp through to the optics bench. In this way issues from the flow cell and its contents can be eliminated as an issue. In this case, you could install the Shunt and power up the detector. If the detector initializes and homes without errors then you have confirmed that the error was caused by some flow cell problem.

    If you do not have the Shunt cell, then we would recommend they contact their local Waters engineer. The Waters engineer can go on site with the Shunt tool and do that troubleshooting.

    (2) If the error still occurs when using the Shunt cell then likely we have a mechanical/electronic problem with the Filter-wheel assembly. In the PDA the Filter-wheel assembly is mounted under the lamp housing of the optics bench. This is a repair best done by a trained Waters engineer. There are critical alignment requirements when replacing a filter-wheel assembly.

    (3) Less Common and lastly there could be other electrical problems such as voltage drops or issues with drivers on the Personality PCB that might cause the same type of error. Again, a trained Waters engineer can best troubleshoot this type of problem.

    (4) If you have another PDA with a known good flow cell, they could install it and do some basic troubleshooting. If the second flow cell works and the detector initializes and homes without errors then they have confirmed that the error was caused by some flow cell problem.

    Hope this helps,


  • I have flushed our F-series Acquity PDA analytical flow cell with de-gassed ACN for several hours @1.0ml/min, have flushed with 50%ACN 50%water for four days @0.5ml/min, and have reset the PDA at least 30 times, all without remedy. My shutter appears to be stuck on the erbium filter and will not home, during startup initialization. After the "shutter assembly could not home" message, I get a PDA error message of "communication failure". What is the likely cause, (besides a bubble-containing or dirty flow cell). We have hardly used this detector since its purchase.