I have a UV-VIS spectrophotometer (VWR, UV-1600) which was out on a research cruise and when it came back to the lab and I tried starting it up, it passed all start up tests but fails the dark current test and then the readings are bouncing all over the place. The only thing the troubleshoot guides say is that the compartment must not be shut correctly, but I've secured it and covered the entire machine in the dark and still the same issue. I have a feeling that the inability to get a dark current reading is a side effect of a different cause, but no idea what. Has anyone else ever had a similar problem?
I think there is a light leak in the compartment. You can try one thing. Wrap the spectrophotometer in a black curtain, switch off the light and then run the test
Thanks for the suggestion but I tried wrapping it in black cloth and running it in the dark, and it still failed the test and the absorbance bounced back and forth from -0.3 to 3.
1. Verify if the tungsten lamp is still lighting.
2. If the answer is yes, a mis-alignment of the light source is probable after a mechanical shock/incident, i.e., no light in the optical path. Put the wavelength at a fixed value, at 500 nm. Verification: Use a white card in dark to see a focused clear image of the tungsten filament somewhere in the sample compartment, in the optical path, where the cuvette is usually placed.
3. Call a service engineer.
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