Asking for help

Dear Catherine,

this is not always a good sign. You can restore the calibration curve of your pump by perfrommig following steps, but be very carefull:

Calibration of Pump Drive

CAUTION: This adjustment will have a major effect on the performance of the

instrument. An invalid calibration curve might lead to a damage of the motor

and/or pump drive! A solid fitting should be placed in the outlet of the pressure

sensor (e.g. remove any connecting tubing).

To calibrate the pump drive:

a) Connect the pump inlet in a bottle containing degassed solvent (CH3OH/H2O, 50/50).

b) Screw a solid fitting into the outlet of the pressure sensor and open the

purge screw.

c) Set the flow rate to 1 mL/min.

d) Access the CALIBRATION screen on the EXTENDED SETUP menu and press

the 4 key to present the current pressure and to start delivery.

e) Adjust the purge value to 1.1 ± 0.1 MPa by closing or opening the purge

screw. Close (open) the valve a few degrees at a time as this is a fairly

sensitive adjustment.

f) Press the4 key again to start the calibration procedure.

Note: After you have started the calibration procedure, do not change the

position of the purge screw!

g) After the calibration procedure is completed, press the 4 key twice to store

the result. If you do not want to save the calibration, press any numeric key.

h) Check the pump pulsation (Section 4.5.8) and adjust the flow rate

Note: The pump drive should run smoothly during operation. When the pump is

operating correctly, there is no vibration and the system is quiet. In addition,

when the slit of the drive wheel passes the optical sensor, the velocity drops to

approximately 50% for a short time.

In case this did not provide solution you will have to replace the CPU PCB.

Good luck and success.

Goran