Varian ProStar 340, Operation Manual

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2. Fasten the tungsten lamp assembly using the same two
screws and aluminum standoffs that are used to fasten the
D2 lamp assembly to the detector.
3. Plug the tungsten lamp power cord into the lower of the two
receptacles located on the detector.
4. Replace the lamp housing and its retaining screws.
Troubleshooting
Most problems with HPLC detectors are actually caused by other
parts of the system. Noisy and drifting baselines, poor
reproducibility in quantitative analysis, and similar problems are
more often the result of dissolved air bubbles, contaminated
eluants, dirty samples, or damaged columns rather than of actual
problems with detector hardware.
To effectively focus on troubleshooting detector problems, on-
board diagnostic tips are discussed first. Then there is a
troubleshooting table organized by symptom, cause, remedy.
Light Intensity Diagnostics
The detector provides the capability of monitoring relative light
intensities at both the sample and reference photodiodes. If an
unusually noisy baseline is noted, relative intensities of reference
and sample light should be assessed. Acceptable values are
dependent upon the flowcell used, wavelength of operation, and
background absorbance. The basic guidelines are as follows:
1. A clean flowcell and good lamp will yield a reference to
sample light ratio of approximately 2:1.
2. An unusually high reference to sample light ratio may
indicate:
•
dirty flowcell
•
excessive absorbance by solvent
3. An acceptable ratio of reference to sample light
accompanied by a reference light level less than 50
indicates a bad lamp.