- During a self-test, the UV-Vis spectrophotometer fails the stray light and wavelength repeatability tests with an “NG9” message. After the self-test, “Error Code = 24” appears, asking whether to continue. What is causing this, and how can it be resolved?
A: “NG9” indicates insufficient deuterium lamp energy (in the UV region). The deuterium lamp is likely aging and needs to be replaced. If you are only using the instrument in the visible light region, you can continue to use it temporarily.
- I have a minor issue with a Model 754 UV-Vis Spectrophotometer. When I push or pull the cuvette holder, there’s no resistance, and the positioning clicks are gone. How can I fix this?
A: The ball bearing beneath the cuvette holder has likely fallen off the spring plate. Simply put it back in place.
- When using a Model 52S UV-Vis Spectrophotometer to measure hexavalent chromium, ammonia nitrogen, and nitrite in water samples, I can zero the instrument and set 100% T perfectly for the hexavalent chromium test. However, for the ammonia nitrogen and nitrite tests, while I can zero the instrument, an error occurs as soon as I try to set 100% T. What could be the reason?
A: The absorbance is out of range. Reduce the concentration of your reference and sample solutions.
- On a Thermo Helios α 5118 UV-Vis Spectrophotometer, during the self-test, it gets to the final “set default” step, an alarm sounds, and it displays “E3093 dark signal too large.”
A: The message “E3093 dark signal too large” means the dark current is too high. This is likely because the sample compartment lid is open.
- The screen of my Shimadzu UV2201 UV-Vis Spectrophotometer displays:
RAM INITIALIZED
SYSTEM I/F INITIALIZE STARTED
iniz: can’t attach “h0”.
iniz: can’t attach “p1”.
iniz: can’t attach “cotaro”
The first self-test item, “BACKUP MEMORY CHECK,” shows “NG” (fail), while the other items pass. After the self-test, the instrument is unusable.
A: A RAM chip in the instrument has failed. This is like a computer’s memory, typically a 62256 chip.
- My UV757CRT UV-Vis Spectrophotometer is connected to a host computer, but the connection fails, and the spectrophotometer displays “CAN NOT FIND LAMPW.”
A: This likely means your instrument’s light source is not on. After startup, the instrument cannot find the characteristic wavelength of the deuterium lamp, so it cannot perform wavelength calibration, preventing a proper startup. This could be due to a faulty deuterium lamp or a problem with the lamp’s power supply.
- I need help with my UV-6100PCS UV-Vis Spectrophotometer. It was working fine a few days ago, but now when I turn it on, the screen is garbled, and then it freezes. Occasionally, it will start up and display “position error” or “data error,” but then it freezes again after entering the warm-up phase.
A: The display board or a program chip on the display board has likely failed. You can try opening the instrument and reseating the chips on the mainboard and the display board.
- My TU1901 UV-Vis Spectrophotometer is showing a “Tungsten lamp energy high” fault.
A: This indicates a malfunction in the light source switching motor. There are two possibilities: 1. The motor itself has failed. 2. The motor’s control circuit or position sensor is faulty.
- After turning on my Model 6010 UV-Vis Spectrophotometer, it shows “D2-failure.” After pressing a key to continue, the subsequent checks are OK, but it fails again at “WL-Calibrate.” After continuing, it shows “energy-low,” and then the rest of the checks are OK. The instrument is usable, but the results are inaccurate. What could be the cause?
A: The deuterium lamp is either failing to ignite or has insufficient energy. Confirm that there is nothing in the sample compartment blocking the light path during the self-test. If the path is clear, then it is indeed a problem with the deuterium lamp.
- My lab’s Cary 50 usually makes a whirring sound when it’s on, but this time it’s silent. The software interface shows “offline,” and I can’t take any measurements. Could the pulsed power supply be broken? The power indicator on the instrument is on.
A: It’s likely a poor connection with one of the internal cards. You need to open the main unit, remove the card, and then firmly re-insert it (reseat it).
- The CRT on my UV-260 UV-Vis Spectrophotometer displays “ENERGY ERROR,” and the instrument will not work.
A: The service manual for the UV-260 points to checking the D2 deuterium lamp. An inspection confirmed the lamp was faulty and not lit, but replacing the lamp did not fix the problem. A detailed circuit check revealed the following:
The voltage between pins ③ and ⑧ of the D2 lamp was normal (~3V). Pin ⑤ is the ignition electrode, which requires a high instantaneous voltage (~300V). The lamp’s operation is controlled by relays RY1 and RY2. The ignition sequence is as follows: RY1 energizes to preheat the filament while capacitor C3 charges. Then, RY1 de-energizes and RY2 energizes, causing C3 to discharge and ignite the lamp. A 76V sustaining voltage is then applied to pin ⑤ to keep the lamp lit.
Upon measurement, there was no voltage at pin ⑤ under any condition. Further inspection found that resistor R7 (100Ω) was open. Replacing this resistor resolved the issue.
- A T6 UV-Vis Spectrophotometer that has not been used for a long time fails the “Wavelength Check” during startup.
A: The optical filters have likely been damaged by moisture (deliquescence). It is recommended to replace them.
- I’m using a Model 721 spectrophotometer, and I’m having a problem. Sometimes the test results are very accurate, but other times when I test a standard, the result is much higher than expected (e.g., a value of 1.10 for a 0.93 standard). I’ve ruled out operational errors and even replaced the lamp. What could be the cause?
A: There are three likely causes for this issue:
- Voltage instability: It is recommended to install a voltage stabilizer.
- Accessory problems: The cuvettes may be contaminated. Try using new cuvettes.
- Environmental factors: High humidity, in particular, can significantly affect test results.
- When I try to zero my UV-Vis spectrophotometer with a blank, it fails. The absorbance value keeps fluctuating. The same thing happens when I try to zero it without a cuvette. Last week, I forgot a cuvette with a liquor cyanide sample inside the instrument and only found it today. Could the cuvette have damaged the instrument, preventing it from zeroing?
A: The instrument has a fault. The zeroing issue is not related to the cuvette.
- When I try to zero my UV-Vis spectrophotometer at a wavelength of 220 nm, it displays “L0.” Other wavelengths are fine. What is the reason?
A: There should be no optical filter in the light path at this wavelength, so a filter problem can be ruled out. The most likely cause is that the deuterium lamp is nearing the end of its life.
- On a Model 752 UV-Vis Spectrophotometer, the Absorbance (A) display shows “over” at startup. When I switch to Transmittance (T) and press 100%, it shows “L0.” If I switch back to A and press 0A to zero, it also shows “L0.” What is happening?
A: Both “over” (in Absorbance mode) and “L0” (in Transmittance mode) indicate low light energy. If this happens in the UV range, the deuterium lamp is likely faulty. If it’s in the visible range, the tungsten lamp is faulty. You can check by looking at the rear of the instrument; you can usually see the glow of the tungsten lamp and the purple light of the deuterium lamp through the ventilation grille.
- The T% reading on my UV-Vis spectrophotometer fluctuates by about 8% and will not stabilize at 100% when there is no cuvette in the holder. What is the problem?
A: Try replacing the deuterium lamp.
- On my 752N UV-Vis Spectrophotometer, the tungsten lamp won’t light up, but the deuterium lamp is on. I replaced the tungsten lamp with a new one, but it still won’t light up. While it was in use, I smelled something burning, and then it failed. I opened it up but can’t see any visible damage. What could be the cause?
A: The “smell of something burning” indicates an electrical problem. The simplest fault would be a broken power wire to the lamp, which might just need to be reconnected. However, it could also be a burnt-out component in the power supply section, which would require inspection by a professional technician.
- The readings from my UV-Vis spectrophotometer are suddenly about double their usual values. What are the possible reasons?
A: The most likely reason is an error in the preparation of your solution.
- Why is my DR6000 UV-Vis Spectrophotometer failing its self-test?
A: 1. Check if there is any foreign object blocking the internal light path.
- Check if the internal copper contacts have become oxidized due to moisture.
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