Agilent LC 1260 minimum stroke

Dear Sirs,


Please help me with the following question relating to our LC 1260.


Recently we had a problem with pump A for error: Servo restart failed/ Stroke length misadjustment


We did change the new active valve cartridge, new pump seal, PTFE frit, Purge valve cap. If  I choose minimum stroke as "automatic", the error still happens. When I change the minimum stroke to 50, the pump was running normally.


Can you explain what was wrong with this pump?


Thank you very much for your time of consideration.


Best regards,

  • Vanphuc:


    Can you provide the model number for the 1260 pump?  The 1260 is a series and there are different model pumps within that series.  The model is found on the lower right corner and begins with G.

  • Hello,


    The pump model is G1312B.


    Thank you

  • Hello,


    The pump model is G1312B


    Thank you for your reply.


    Best regards,

  • Hello vanphu,


    Thanks for the model information.  On power on, the motor needs to move the pump to specified positions and if it fails to do so in a range of motor steps, it can give the error you mentioned.


    We advise to leave the pump stroke in auto to allow the pump to set it automatically based on flow rates.  By specifying a fixed stroke, the pump will always deliver that volume on a complete piston stroke cycle.  What is most puzzling by what you wrote is that the error doesn't appear when the stroke is fixed.


    I think the issue may be with the pump head and not the pump drive.  To test, switch the pump heads and see if not pump B has the problem. If yes, then there is something not quite right with the pump head.  If the problem remains, that leaves the pump drive as the issue.


    Let me know what you find as this is a new one for me.

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