biochrom ultrospec 7000 User Manual page 9

If the equipment is operated in a manner not specified, then the protection provided by the equipment may be
impaired and the instrument warranty withdrawn.
1.4.1. Troubleshooting
PROBLEM
Start up calibration fails
Negative absorbance reading
Unexpected results
Start up calibration fails
Negative absorbance reading
Absorbance values higher than expected Check for use of incorrect cell type.
Absorbance value lower than expected
Instrument will not reference
Poor reproducibility with nucleic acid
analysis
5061-046 Rev1
POSSIBLE CAUSE
Check sample (and reference) beam is clear before switch on. Possible optical
failure, contact service support.
Check that sample and reference cells have not been swapped
Check sufficient height of sample solution (beam height is nominally 15 mm
above the cell base for normal measurements and it is recommended that it be
filled to 20 mm above the base).
Check for bubbles in solution.
Check sample (and reference) beam is clear before switch on. Possible optical
failure, contact service support.
Check that sample and reference cells have not been swapped.
Check sufficient height of sample solution (beam height is nominally 15 mm
above the cell base for normal measurements and it is recommended that it be
filled to 20 mm above the base).
Check cells are free from finger prints.
Check cells for contamination.
Check cell orientation.
Check reference used.
Possible optical alignment problem, contact service support.
Check sufficient height of sample solution.
Check sample and reference are not the same.
Check sample compartment lid is properly closed.
Possible stray light issue, contact service support.
Check orientation of cuvette.
Check for use of incorrect cell type.
Check for particles, try using background correction.
Try increase in concentration.
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