Oct 27 , 2021
How to overhaul high and low temperature test chamber instruments?
The method of overhauling the instrument of the high and low temperature test chamber:
In the whole process of long-term production, supply, and marketing, our company often encounters customers who do not understand how to maintain the instrument panel of the alternating high and low temperature box. Today, our company will explain this problem in detail.
Method one: comparison method
The specific method is: let the instrument panel with common faults and all normal instrument panels operate under the same conditions, and then check the data signals of some points and then compare the two sets of data signals. If there are differences, it can be judged that the common faults are located here. This type of method requires maintenance personnel to have very professional knowledge and professional skills.
It is stipulated that there are two identical dashboards, and one is all operating normally. To apply this type of method, you must have the necessary equipment, such as digital multimeters, digital oscilloscopes, and so on. According to the comparative characteristics, it is divided into comparatively working voltage, comparatively wave type, comparatively static data characteristic impedance, comparatively output result, comparatively current quantity and so on.
Method 2: capacitor bypass method
When a certain power circuit causes a strange situation, such as a display screen disorder, the capacitor bypass method can be used to clarify the part of the power circuit that has a common fault.
Method three: isolation method
The common fault isolation method does not use the same type and specification of machinery equipment or accessories for comparison, and it can be trusted. According to the common fault inspection process table, segmentation encloses the gradually smaller common fault retrieval category, and then cooperates with data signal comparison, component exchange and other methods, and usually finds the common faults quickly.
Method 4: Beating method
We often encounter intermittent conditions in the operation of equipment and equipment. Most of these conditions are caused by poor contact or empty welding. For this type of situation, tapping and hand-clamping methods can be selected.
To put it bluntly, “knock” is the location that is likely to cause common failures. Tap the software board or component lightly according to the small rubber finger or other beating objects to see if it will cause errors or shutdown common failures. To put it bluntly, “hand clamp” means that when common faults occur, the components and power plugs and sockets that are plugged in after turning on the switch power supply are clamped by hand again, and then restart and try to clear the common faults. If you find that everything is normal after one tap on the shell, and then it is abnormal again, it is best to reinsert all the connectors firmly and try again. If it fails, you can only find another way.
Method 5: Situational regression analysis method
Generally speaking, before the common faults are uncertain, there is no need to arbitrarily move the electronic devices in the power circuit, especially the adjustable components, such as resistors. However, if the paperless recorder adopts counter-referencing countermeasures in advance (for example, marking the parts or measuring the working voltage or resistance before moving), it is still allowed to be touched when necessary. Maybe some common faults will be cleared after the change.
IC’s switching power supply and ground terminal; ground the transistor power supply circuit at the base input terminal or collector junction output terminal to observe the harm to common fault conditions. If the capacitor bypass the input terminal of the colorful paperless recorder fails and the common fault condition disappears when the output terminal is bypassed, it is clear that the common fault occurs in the primary power circuit here.
Method 6: Observe
Use visual effects, taste, and touch. In some cases, damaged components will fade, blisters or burned black spots; burnt components will cause some unique flavor; integrated IC with short circuit failure will heat up; empty soldering can also be observed by the human eye Or open the weld.
What is the basic principle of cold and wet exchange of high and low temperature test chambers?
When the high and low temperature test chamber is testing, when the gas hits the river surface, it will exchange with the dampness and heat generated by the opened river surface. The temperature difference will cause two conditions, one is that only sensible heat exchangers are produced, and the other is that not only is it possible to produce sensible heat exchangers, but it is also likely to produce moisture exchange, and it can also produce vaporization. Hot swap.
The sensible heat exchanger appears because there is a temperature difference between water and gas, and heat transfer is carried out due to the effects of heat convection, heat transfer and radiation source. The volatilization of water vapor in the air and digestion and absorption of the latent heat of vaporization will result in the exchange of vaporization heat.
The contact between the river surface and the gas, because the gas is close to the river surface, will produce a saturated gas boundary as a result of irregular fitness exercises. At this time, its temperature will be equivalent to the temperature of the river surface. The gas temperature in the saturated state of the boundary layer determines the concentration value of the water vapor molecular structure or the size of the water vapor partial working pressure.