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Circuit breakdown analyses the commonly used method with fixed position

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The breakdown type of digital circuit is more, the account that produces breakdown also has each different, the method that eliminates breakdown accordingly is different also. When circuit malfunctions, according to breakdown phenomenon, through the examination, measure, the reason that analyses breakdown generation determines the position of breakdown, find the process of yuan of malfunctioning parts of an apparatus. Compare simple circuit commonly, its breakdown reason also often is compared simple, the analysis of breakdown and fixed position are cushier; And relatively complex circuit, its breakdown often relatively complex also, it is a few more difficult that the analysis of breakdown reason and fixed position also are about relatively. The commonly used method of circuit breakdown analysis and fixed position discusses below. One, direct observation way is alleged and direct observation law is to point to not have the aid of at any instrument equipment, direct observation yets to be investigated the surface of circuit will discover the problem, means that seeks breakdown, general component checks two kinds for static observation and electrify, among them static state observation includes content of following a few respects. 1, observation printed circuit board reach surface of yuan of parts of an apparatus to whether have scorched print, reach even the line yuan of parts of an apparatus to whether have fall off, rupture wait for phenomenal happening. 2, scope uses a case. Instrument type choice is right, of function, span choose have without accident, in all connective is handled whether appropriate. First selection removes exterior trouble, have the observation of circuit itself again. 3, circumstance of observation circuit power supply. Whether do the voltage value of power source and polarity accord with a requirement, whether did power source already receive circuit really etc. 4, observe yuan of parts of an apparatus to install a circumstance. Electroanalysis the down-lead terminal of the polarity of capacitance, diode and dynatron, down-lead terminal of integrated circuit has without receive wrong, fumble, each other to touch wait for a circumstance, installation place is logical, have to faze source wait without screen measure. 5, observation wiring circumstance. Communication and strong report and input and output line, weakness line, dc line whether to violate wiring principle. After the static state observes, can undertake electrify is checked. After receiving electrify source, observe yuan of parts of an apparatus to have without send the case such as very hot, fume, transformer has do not have scorching or give out heat reach unusual noise. Observe the law applies to pair of breakdown to undertake preliminary check-out directly, can discover a few relatively the breakdown of detail. 2, the instrument tests a standard 1, cut off the power test law is cut off the power in circuit below the condition, use avometer ohm archives measures circuit or yuan resistance of parts of an apparatus, so as to judges the method of breakdown. If dot of line, solder and frit silk are connected in examination circuit,wait to whether open circuit, measure leakage of electricity of resistance, capacitor, inductor connect, the stand or fall that checks semiconductor device. When the test, to avoid the effect of relevant spur track, be measured the one aspect of the matter of yuan of parts of an apparatus should disconnect with circuit commonly, in the meantime, to protect yuan of parts of an apparatus, do not use tall hold back and low hold back, in order to prevent the PN knot of the semiconductor device in tall voltage or circuit of attaint of big electric current. 2, electrified test law is in circuit electrified condition falls one kind, have the aid of measures value of voltage of each bits of static state in circuit or voltage weaveform to wait at the instrument, undertake theoretical analysis, search breakdown to be in the method of place. It is normal that if examine transistor static state,the job is nodded, whether does the static parameter of compositive parts of an apparatus accord with a requirement, the logic of digital circuit concerns to wait whether correctly. 3, signal finds slash way is the signal that accords with a requirement according to needing to input end to join in circuit, the class after according to the flow of signal class arrived once upon a time, with the instrument such as oscillograph or volmeter signal of the examination that pursue course is inside circuit the circumstance that each part Huang Zijian transmits, the function that analyses ID An Lu is normal, judge breakdown to be in place thereby. This kind of method is used below the condition with answer to be in in place of work of circuit static state normal normally. 4, break up test law annular to what a few have feedback circuit, their various working circumstance each other has embroil, can use the method that breaks up annulus road at this moment, feedback annulus take out, chase class examination next, can faster failure isolation place. To self-oscillation the phenomenon also can use examination of this kind of method. 5, when antitheses suspects some circuit existence problem, can look for an identical normal circuit to undertake comparing is opposite, will both condition, parameter undertakes item-by-item contrasts, can find the abnormal parameter in circuit very quickly, assign account of separate out breakdown then and search breakdown to nod. 6, substitution method sometimes breakdown concealments quite, cannot find very quickly, need further examination, can replace with the unit circuit that already had debugged or component at this moment have interrogative unit circuit, will judge with this whether to go out in this unit circuit. After deciding the unit circuit that has a problem, still can be in local substitution method should be used in unit circuit, replace with yuan of parts of an apparatus that affirms yuan of good parts of an apparatus to have suspicion the problem come down, the distrustful limits of progressively and contractible breakdown, find breakdown place finally. CNC Milling