Many teaching and research departments in medical colleges and universities ( such as chemistry, biochemistry, disease, pharmacology, etc.) use various types of colorimeter( colorimetric meters). Colorimeters are expensive and easy to damage, such as department students use, damage more frequently, so repair use has become an important problem. The general maintenance personnel does not understand the principle and use of the colorimetric meter, while the teaching and scientific research personnel do not understand maintenance, so sometimes they are not used after maintenance. It is also extremely unfortunate that some instruments are scrapped without repair. We have accumulated some experience in the use and hands-on maintenance. Here, we analyze and discuss the problems that often occur in the use and maintenance of communication with you.
First of all, the common and easily overlooked problem is the deviation of monochromatic light
If the effect of the repaired colorimeter becomes worse or cannot be used at all, the wavelength deviation is actually large. The wavelength deviation may occur after the colorimetric meter is used for a period of time or after maintenance. This is because monochromatic light is obtained by light reflected from the moving prism. The mechanical rotation part is prone to deviation due to use and movement, resulting in wavelength error. Therefore, the measurement results are errors, and this error is often not found. So adjusting the wavelength is particularly important. Using a piece of colored filter provided by the instrument, adjust the position of the prism through three adjusting screws in the instrument, so that the output light is adjusted in a certain range, so as to meet the wavelength requirements.
Problems of the light gate
Since the instrument controls the closure of the optical door by switching the colorimetric box cover, the cover is prone to failure due to frequent switching and switching. The situation can be determined by placing a white paper in the colorimetric box and observing the incident light. Note that even if the aperture has a small gap, will affect the results of colorimetric analysis. The light door closed not close, only take off the colorimetric box slot, adjust the light door, carefully repair it.
The problem of panel up-regulating the zero-sum 100 % potentiometer
There are two multi-loop potentiometers on the instrument panel to adjust zero and 100 %, respectively. Some colorimeters ( such as Pocket Colorimeter for Lab) have defects in design, it is through a large resistance potentiometer and a small resistance potentiometer in series to zero. The potentiometer with smaller resistance is placed on the panel, and the potentiometer with larger resistance is placed inside the instrument. Potentiometers on the panel often cannot be adjusted to zero, and students do not know that there is a potentiometer adjustable to zero in the instrument. The multi-loop potentiometer is extremely vulnerable to damage the ring with a little effort. Therefore, before using the colorimetric meter, it should be clear to students to reduce damage. At the same time, it is recommended that manufacturers put the potentiometer with large resistance value on the panel, so that it is easy to use and reduce the damage of the potentiometer. Sometimes the pointer of the instrument panel vibrates, and sometimes the pointer drifts after adjusting zero or 100 %, which is often the problem of potentiometer. After the potentiometer is used for a long time, the contact point often has poor contact. If this phenomenon occurs, if it cannot be repaired, it can only replace the new potentiometer.
Problems in circuit part
Since the instrument requires stable input and output light, there must be a power supply. Colorimeters generally have two sets of voltage stabilizers. For example, the voltage change of power supply is not too large, and it is not equipped with special voltage stabilizers. On the contrary, there should be a voltage stabilizer.
The failure of the power supply part often occurs that the indicator light is not bright or the bulb has a flicker. If there is no output voltage, it is basically judged that there is a problem in the voltage stabilizing part of the power supply. This may be diode bad, regulator bad, capacitor bad, etc., according to different situations repair. Since the current generated by the phototube is very small ( microampere level ), it must be amplified by the amplifier, and the amplifier also has a set of independent voltage stabilizing power supplies to obtain more accurate voltage stabilizing purposes. If there is a problem in this part of the power supply, the specific problem is analyzed in detail. From our experience, the probability of this part of the problem is very small.
Other faults
The photocell has a certain service life. If it exceeds the service life, the performance will decrease. The specific performance is that it cannot be adjusted to 100%. At this time, the sensitivity switch can be set to a larger one. After a period of use, it cannot be adjusted to 100%. At this time, you should consider replacing the photocell. Although the sensitivity switch is turned up, it can still be used, but the reading error will be large at this time, so it is generally not suitable to use it again. From our experience, if the sensitivity switch is greater than 2 gears, it should not be used again. The above introduces some problems and solutions that often occur in the use of caliber 4mm handheld color meter, hoping to get the attention of peers, further improve the use value of the instrument, and reduce unnecessary losses.