User manual

Fault Action
Low sensitivity 1 Aging lamp. Check the lamp and replace if necessary
2 Wrong lamp position. Check that the lamp position and the
wavelength used (filter position) fit together.
3 Dirty on-line filter. Clean or replace the filter.
Error in external chart recorder 1 Check the chart recorder in accordance with its manual.
2 Test the recorder function by selecting recorder test
according to section B.1 in Reference Information.
pH measurement (optional in ÄKTAFPLC systems)
No response to pH changes 1 Check that the electrode cable is connected properly to
the rear of the module.
2 The electrode glass membrane may be cracked. If so,
replace the electrode.
Small response to pH changes 1 Clean the pH electrode according to section 4.8 and
recalibrate.
2 If the problem remains, replace the pH electrode.
Slow pH response or
calibration impossible 1 Check the electrode glass membrane. If it is contaminated,
clean the electrode following the instructions in section
4.8 Cleaning the pH electrode.
2 If the membrane has dried out, the electrode may be
restored by soaking it in buffer overnight.
3 Clogged liquid junction. Refer to section 4.8 Cleaning the pH
electrode.
Incorrect/unstable pH reading 1 Check that the electrode cable is connected properly to
the rear of the module.
2 Check that the pump operates correctly.
3 Check that the electrode is correctly inserted in the flow cell
and, if necessary, hand-tighten the nut.
4 If air in the flow cell is suspected, tap the flow cell carefully
or tilt it to remove the air. Alternatively, flush the flow cell
with buffer at 20 ml/min for 1/2 min. Use a flow restrictor
after the pH electrode.
5 Check that the pH electrode is not broken.
6 Check that the pH electrode is calibrated.
7 Check the slope (see section 3.10 Calibrating the pH
electrode). If it is outside the range 80–105% or if the
asymmetry potential deviates more than ±60 mV from 0 mV,
clean the pH electrode. Recalibrate. If the problem persists,
replace the pH electrode.
8 Clean the pH electrode if required, see section 4.8 Cleaning
the pH electrode.
9 Compare the response of the pH electrode with that of
another pH electrode. If the response differs greatly, the
electrode may require cleaning or replacement.
Monitor UPC-900
User Manual 18-1125-55 Edition AE
28
5 Trouble-shooting