Many peers have reported that the components of a faulty mobile phone have been changed, but the repair is not good. In most cases, the mobile phone circuit is not fully understood, and the mobile phone circuit diagram will not be read and analyzed. "The three axes will go down, although they can solve some problems, but if you go deeper, you will be helpless.
Many people have a headache when they see the circuit diagram. They feel that they have no clue and can't start. In fact, mobile phone electrograms have a strong regularity. Let's talk about some basic methods of reading mobile phone circuit diagrams.
Mastering the position, function, characteristics of the main components, and what technical indicators can be passed, and thoroughly understanding their functions, can help us understand the guiding ideology and layout of the circuit diagram. Also, pay attention to the components on the circuit diagram, the block diagram, and the component distribution diagram. If necessary, several diagrams of the physical board are combined with each other to analyze, and also the positive and negative poles of the components cannot be connected. In contrast, the symbol of the diode system, a triangle on the left, a short strip on the right, the lead on the side of the triangle is the positive pole, and the lead on the side of the short strip represents the negative pole. For the electrodes of the triode and FET, the correct sequence of the integrated IC steps should not be connected incorrectly. In the maintenance, you should also avoid connecting the places that should not be connected. If there is a place where the "+" is not connected, you cannot connect them together. Pay special attention when flying the line.
　　
The whole schematic is turned into several parts. For example, when analyzing the working principle of the RF part, we often analyze the receiving part, the transmitting part and the frequency synthesizer circuit separately. This part of the circuit can be Subdivided into many branches. In the process of subdivision, if there are individual components or principles, it is difficult to understand, you can postpone the research. In this step, you only need to find out the main modules and components of each part.
　　
<br> <br> comprehensive analysis of the various components of the upcoming comprehensive. From the input of the total circuit diagram to the output, observe how the electrical signal is transmitted and amplified step by step in the circuit.
　　
Comparative Analysis <br> <br> circuit for each basic unit, wherein the DC path identify, AC path and a feedback path, a static bias determination circuit is appropriate, whether the AC signal amplifying and transmitting parties, the signal lead After what kind of filtering, otherwise, the short circuit will cause other faults. Be familiar with the characteristics of various basic circuits. For example, the basic circuits such as various amplification, oscillation, detection or phase-locked loops should be well-documented and analyzed. It is easy to look at the circuit diagram later. For example, the L2000 series mobile phones and the V998 series work in much the same way. When analyzing the circuit diagram, you can compare the main mobile phone circuits at the same time. In this way, you can get twice the result with half the effort, and analyze the evolution process of the newly launched TAICHI series mobile phones and P2K mobile phones to achieve the ability to change. For the same type of integrated IC, in addition to comparing the efficacy in the same brand series circuit, it should be compared with other brand models to analyze the same and difference, because the introduction of modern mobile phone models is endless, the function is different but the specification Always do not leave the GSM standard, the basic circuit works in much the same way, doing the above work, can give a counter-three, and quickly respond to the dazzling fault of the ever-changing mobile phone.
　　
Index estimates <br> <br> order to strengthen a more in-depth understanding of circuit diagrams can be for some of the major technical indicators some estimates, in order to obtain quantitative concept for the technical performance of the circuit, the components of the electrical function and pin The parameters should be mastered, and if necessary, use instrumentation to verify, and dare to use facts to doubt the accuracy of the circuit diagram. Because some repair book drawings are not original drawings.
The above methods are more suitable for the working part of the RF part of the mobile phone. For the logic part working circuit, the main points we should grasp are as follows:
Power supply circuit: Analyze how the power supply is combined with the chip, component display, etc.
Clock circuit: Analyze the clock drive circuit, which pin is connected to the integrated IC;
Reset circuit: that is, which pin of the integrated IC is specifically connected to the RESET;
The input channels of the SIM card holder, the keyboard, and the microphone are generally more prone to problems in their input paths;
Display, backlight, indicator light, ringer/handset output path.
Of course, when analyzing the logic part of the circuit, we must first understand the basic characteristics of each major integrated IC. Such as: central processing unit, chips, fonts, audio modules, and so on. Through the above analysis, master their internal quality and control essence.
The above methods are not fixed, and are not suitable for any mobile phone circuit. Sometimes the methods are not clearly defined, can be cross-over, the order can be reversed, and should be flexibly applied according to actual conditions.
This article refers to the address: http://
Automotive Connector
Dongguan Andu Electronic Co., Ltd. , https://www.idofuseholder.com