What should I do if the laboratory equipment is malfunctioning?

Without guaranteeing the strong maintenance of equipment and equipment, it is difficult to carry out experiments and scientific research work normally!

Trouble: After the analytical balance presses the "i/o" key, there is no display on the electronic balance

First of all, ask the user about the usage, don't rush to disassemble it, ask the user about the usage, the phenomenon of the failure and the abnormal phenomenon before the failure, etc.

Secondly, test machine observation, observation includes watching and smelling, observing the appearance changes of the components of the equipment, such as whether the fuse is blown, whether the fastener is loose, whether the whole machine is smoking, whether the internal short circuit of the instrument causes a trip Phenomenon; smell whether the instrument emits a burnt smell

Finally, on the basis of inquiry and observation, based on the working principles of different instruments and equipment, combined with the failure phenomenon, determine the cause of the failure

Possible Causes:

(1) The fuse of the electronic balance is blown;

(2) The power is not connected;

(3) The keyboard has an error and the keys are stuck

Secondly, loosen the button fixing screw, adjust the button position, and check again, if there is no display, analyze the reason (3);

Finally, replace the fuse, first unplug the power cord, use a small screwdriver to pry open the fuse box at the power socket of the electronic balance, and replace with a new fuse

1.

This type of failure is mainly caused by improper laboratory environment temperature and humidity, unstable power supply voltage, external electromagnetic field and vibration of the instrument

Under environmental conditions such as high temperature, high humidity, poor ventilation, etc.

2.
Malfunction caused by improper operation and use process

If the operator does not operate properly during the experiment, causing some liquid to flow into the circuit board or components inside the instrument, chemical corrosion and electrochemical corrosion will occur, which will damage the instrument
.

Some instruments and equipment must be warmed up for a period of time after they are turned on before they can be used, and some instruments and equipment must be adjusted and calibrated as required after they are turned on before they can be used
.
If the symptoms before the failure of the instrument fail to attract the user's attention, it is very likely to cause damage to the instrument
.
These man-made faults caused by improper operation should cause the managers to pay enough attention
.

3.
Failures caused by poor quality of the equipment itself

Carbon film potentiometers, multi-turn potentiometers or mechanical parts can cause equipment failure due to wear, oxidation or poor contact; the performance of the components used in the equipment is poor.

For example, unstable performance of semiconductor devices, integrated circuits, resistors, capacitors, etc.
can also cause failures; equipment manufacturers' backward manufacturing processes, false soldering of components, and poor plug-in contact can also cause the instrument to be used due to instantaneous current high.
The breakdown of components causes short-circuit or open-circuit faults
.

Troubleshooting method

Due to the different structures and working principles of various experimental instruments and equipment, even if the same instrument and equipment have the same failure phenomenon, the cause of the failure may be different
.

At present, instruments and equipment are constantly being updated, and the two generations of the same instrument have different internal structures, which brings some trouble to maintenance
.

Therefore, in order to ensure the safe, stable, and orderly operation of teaching and scientific research experimental equipment, maintenance engineers and technicians are required to be familiar with the performance of various instruments and have a comprehensive understanding and solutions to the failure of the equipment
.

In the maintenance process, we must be good at observation, accurate judgment, flexible application of various maintenance methods, and strive to find some common problems in instrument maintenance
.
The maintenance steps and general methods of the equipment are shown in the figure
.

1.
Ask the user about the usage: After receiving the faulty equipment, the maintenance technician should not rush to disassemble it, but ask the user about the usage, the phenomenon of the failure and the abnormal phenomenon before the failure, etc.
, and make a record for the next maintenance.
Get ready
.

2.
Test machine observation: Observation includes watching and smelling, observing the appearance changes of the components of the equipment, such as whether the fuse is blown, whether the fastener is loose, whether the whole machine is smoking, whether the internal short circuit of the instrument causes a trip Phenomenon; smell whether the instrument emits a burnt smell
.

3.
Measurement: This work is based on inquiries and observations, based on the working principles of different instruments and equipment, combined with failure phenomena, to determine the cause of the failure
.
You can use a multimeter to detect the voltage and current of the relevant points, and use the oscilloscope to detect the waveform diagram of the corresponding point, narrow the scope of finding the fault, and determine the fault location and fault components
.

1.
Intuitive repair

A common failure phenomenon of the instrument is that there is no display when it is turned on
.

If it is a mechanical failure, check whether the gear is worn, whether the transmission belt is aging or broken, whether the pillar or bolt is loose, etc.
; if it is a circuit failure, check whether the power supply part is normal and whether the fuse is blown
.
According to the blown degree of the fuse wire, it can be judged whether the fault is caused by the inside of the instrument or by external factors
.
If the fuse is black, it is often a short circuit of high-power components inside the instrument; if the fuse is clear, it is often caused by the unstable external power supply voltage and current of the instrument or a small component failure inside the instrument
.

In addition, due to long-term use, the light source lamps of optical microscopes, spectrophotometers, etc.
, the lamp feet are easily oxidized, resulting in poor contact and cannot be lit.
Polished with fine sandpaper can return to normal use
.

The internal relay contacts of the instrument are oxidized, and the flexible switch contacts of various instruments, the function selection contact buttons of the touch film screen, etc.
can be polished with fine sandpaper or treated with a contact cleaner
.

2.
Alternative maintenance

In the repair process, if the components that need to be replaced cannot be purchased for the same model at a time, you can choose the alternative method
.

For example, if the maintenance sampling value cannot meet the requirements of the KC-120H intelligent medium flow TSP sampler, the 1.
5KΩ multi-turn potentiometer is found to be invalid, and the same resistance component cannot be purchased on the market, then the resistance value is not much different.
The 2kΩ multi-turn potentiometer is replaced, and the instrument returns to normal
.

Under normal circumstances, substitute potentiometers with close power and slightly larger resistance can be selected; for the substitution of transistors, one with close parameter values ​​can be selected according to parameters such as withstand voltage and breakdown current
.

3.
Contrast repair

When some instruments fail, the user cannot provide the instruction manual and circuit diagram, and even the equipment manufacturer does not provide the circuit diagram at all
.

In this case, it is necessary to use the comparison method or the reference method to repair.
When the faulty component is burned, corroded, and oxidized and the parameter value cannot be confirmed, you can view the circuit of the same part of the same instrument with the same function.
There are some components in the circuit.
The group has consistency and symmetry
.
Compare and test the parameters of the corresponding components of similar instruments to provide a reference basis for troubleshooting
.

4.
Measurement analysis method maintenance

For some instruments and equipment with more complicated internal circuits, they should be divided into several parts according to their functions, and they should be analyzed and inspected in a targeted manner.
Use a multimeter to measure the voltage of the relevant point and compare it with the normal value.
Use an oscilloscope to observe the waveform signal to analyze the fault range.
Find out the faulty components in the circuit
.

The maintenance of equipment is a comprehensive and highly technical work
.

Therefore, the establishment of a high-quality, skilled instrument and equipment maintenance team and strengthening the maintenance of equipment are the prerequisites for improving the intact rate and utilization rate of the equipment, and it is the fundamental to maximize the efficiency of the equipment and ensure the smooth progress of the experimental tasks.
Guarantee is also a practical topic that experimental technicians should explore
.
Instrument and equipment maintenance is also a process in which experimental technicians continue to accumulate rich experience and improve maintenance techniques
.