Electron yuan characteristic of breakdown of parts of an apparatus
The electron of wiring interior yuan parts of an apparatus although the amount is very much, but its breakdown is to have the law however but of abide.
The characteristic resistor that 1. resistor damages is the component with the maximum amount in wiring, but not be the component with attaint top rate. Resistor damages with open circuit the commonnest, block value greatens scarcer, block value decrescent is very scarce. Resistor of common film having carbon, metallic film resistor, line circles resistor and insurance resistor a few kinds. Before two kinds of resistor application are the widest, the characteristic that its damage is low block value (100 Ω are the following) be worth with tall block (100k Ω above) attaint rate is higher, intermediate block is worth (if hundreds of Europe go to a few Europe) few attaint; 2 it is low block when resistor damages, the value often is to scorch nigrescent, discover very easily, and there is a mark rarely when tall block is worth resistor to damage. The line circles resistor to use as commonly current limliting of big electric current, block value is not great. Cylindrical some meetings when the line circles resistor to burn out nigrescent or the surface explodes skin, crackle, some does not have a trace. Cement resistor is a kind when the line circles resistor, when burning out, may rupture, also did not see a mark otherwise. Meeting blast drops some surfaces when insurance resistor is burned-out a skin, some also does not have what trace, but won't scorch absolutely nigrescent. According to above characteristic, can emphasize particularly on somewhat when checking resistor, find out the resistor of attaint quickly.
2. electroanalysises the characteristic that capacitance damages electroanalysises capacitance the dosage in wiring is very big, fault rate is very high. Electroanalysis capacitance attaint has the following kinds of show: It is to lose capacity or capacity decrescent completely; 2 it is slight or serious leakage of electricity; 3 it is to lose capacity or capacity decrescent to hold leakage of electricity concurrently. Search attaint electroanalysis capacitance method has:
(1) look: Fluid can leak when some capacitance damage, the circuit below capacitance board the surface even capacitance appearance can have an oily floodwater on low-lying land, this kind of capacitance is absolutely cannot reoccupy; Beat of the meeting after some capacitance damage rises, this kind of capacitance also cannot continue to use;
(2) feel: The some leakage of electricity are serious electroanalysising after switching on the mobile phone capacitance will be calorific, point to to the hand can be warmed even when feeling with the hand, this kind of capacitance must change;
(3) electroanalysis capacitance interior has electrolyte, long roast meeting makes electrolyte desiccate, bring about capacitance to reduce, should check carbon fin and high-power mainly so yuan the capacitance near parts of an apparatus, closer from its, the possibility of attaint is larger.
3. 2, the characteristic; that the semiconductor device such as dynatron damages 2, the attaint of dynatron is PN knot puncture or open a way commonly, be in the majority with puncture short circuit among them. Still have show of two kinds of attaint in addition:
It is thermal stability becomes poor, expression is when switching on the mobile phone normal, after working for some time, produce soft puncture;
Another kind of character that is PN knot becomes poor, measure with 1k of avometer R × , each PN writtens guarantee all normal, but on cannot work normally after machine, if use R × 10 or archives of 1 low span measures R × , with respect to meeting discovery its PN knot is worth to block bigger than normal value. Measure 2, dynatron can use avometer of pressing with a finger to be measured in the road, more accurate method is: × of avometer buy R 10 or 1 archives of R × (use R × commonly 10 archives, unidentified × of R of the reoccupy when showing 1 archives) measure in the road 2, the PN of dynatron writtens guarantee, retrorse resistor, if to resistor not quite big (relatively normal value) , retrorse resistor is enough big (opposite to the value) , show this PN form is normal, conversely suspectable, after needing solder to fall, measure again. Because,this is of general circuit 2, dynatron periphery resistor is in mostly hundreds of, above of thousands of Europe, with avometer low block is worth archives to be measured in the road, the effect of resistance of periphery of OK and basic oversight to PN knot resistor.
The structure of interior of characteristic integrated circuit of 4. integrated circuit attaint is complex, the function is very much, any one part attaint cannot work normally. The attaint of integrated circuit also has two kinds: Complete attaint, thermal stability is undesirable. When complete attaint, can tear open its below, with be the same as contrast of model integrated circuit to measure its normally each cite a base to the ground, retrorse resistor, always can find among them or value of a few block that cite a base is unusual. Poor to thermal stability, can be when facility work, with the integrated circuit that anhydrous alcohol refrigeration is suspected, if breakdown happens to time is deferred or malfunction no longer, can decide. Can change only normally new integrated circuit will eliminate.
Of dynatron detect
Of dynatron of 1 medium, small-power detect
The dynatron that A foregone model and pin arrange, can judge its function stand or fall by undermentioned method
(A) is measured extremely resistor. × of avometer park R 100 or R × 1k is blocked, differ according to 6 kinds of pen of red, black list receive a law to have a test. Among them, comparing of emissive knot and market report knot to resistance low, other 4 kinds of resistance that receive a law to be measured are very tall, come for hundreds of 1000 Europe about infinity. But no matter be low block or tall block, of silicon material dynatron extremely resistor wants to compare germanium material dynatron extremely resistor is gotten greatly much.
(The product of the diploid β that the numerical value of the Iceo of penetrable electric current of B) dynatron is equal to pipe approximately and the Icbo of retrorse electric current that market report writtens guarantee. Icbo as environmental temperature elevatory and growth is very rapid, the addition of Icbo causes the accretion of Iceo necessarily. And the increases job of pipe of will immediate impact stability of Iceo, so in use should choose the pipe with small Iceo as far as possible. Measure dynatron E directly through using avometer resistor - the resistor method between C pole, can estimate the volume of Iceo secondhand, specific means is as follows: The span of avometer resistor chooses R × commonly 100 or R × 1k is blocked, to Pnp canal, black list canal receives E pole, red watch pen receives C pole, to Npn dynatron, black list pen receives C pole, red watch pen receives E pole. Ask measures resistance has been jumped over greatly more. E - the block value between C is greater, the Iceo that shows tube is smaller; Conversely, what measure block the value is less, the Iceo that the specification is measured to be in charge of is bigger. Say commonly, low frequency of material of canal of medium, small-power silicon, germanium is in charge of, its block value should be in hundreds of 1000 Europe, a few Europe to reach ten Europe above respectively, if block is worth very small or finger of the avometer when the test makes a round trip rock, show Iceo is very big, the performance of pipe is not steady.
(C) measures enlarge ability (β ) . At present the avometer of some model has the graduation mark that measures dynatron Hfe to reach its to test electrical outlet, can very the enlarge that measures dynatron conveniently is diploid. Dial avometer function switch first block to , span switch dials Adj position, red, black list pen weak point is received, adjust zero knob, make avometer finger is indicated for 0, dial span switch Hfe position next, make two short the received departure that express a pen, insert the dynatron that be measured test electrical outlet, can numerate from Hfe graduation mark the enlarge of pipe is diploid. Additional: Have the dynatron of medium, small-power of this model, manufacturer home is direct the value of enlarge multiple β that in its envelope coping designation gives different quality point to make clear pipe, if its color and the corresponding relation that β is worth express place to show, but want to notice, bid of coloring of each manufacturer place is not fair identical.
B detects differentiate electrode
(A) decides base. With avometer R × 100 or R × 1k is blocked measure dynatron in 3 electrode every two extremely between, retrorse resistance. Should receive some electrode with pen of the first watch, and pen of the 2nd watch contacts additionally two electrode to all be measured lowly early or late when block is worth, criterion that electrode that the first place that express a pen receives is base B namely. At this moment, want to notice avometer expresses the polarity of the pen, if red watch pen is received, is base B. Black list pen is received respectively in other and polar when, measures block value is lesser, can decide the dynatron that be measured is Pnp canal; If black list pen is received, is base B, red watch pen parts when the contact is other and polar, measures block value is lesser, be measured dynatron is Npn canal.
(B) decides collector C and blast off extremely E. (It is with Pnp exemple) × of avometer park R 100 or R × 1k is blocked, b of the red base that express a pen, when with black list the pen contacts additionally two pin respectively, two resistance that measure can be a few bigger, a few smaller. In be measured block value is little, the black place that express a pen receives pin to be collector; In block the value is measured bigger in, the black place that express a pen accepts pin to blast off extremely.
C differentiate is high frequency canal and the cut-off that low frequency is in charge of high frequency canal frequency is more than 3mhz, and the cut-off that low frequency is in charge of frequency is less than 3mhz, usually, both is cannot of crossing-over.
D detects in road voltage judgement law is applying dynatron of medium, small-power actually to solder directly more in printed circuit board on, because the installation density of component is big, disassemble more troublesome, When detecting so, often block through using avometer volts d.c. , go the voltage value that measures the dynatron that be measured to cite a base each, will conclude it is normal that its work, judge its stand or fall then.
Of dynatron of crystal of 2 high-power detect use avometer to detect all sorts of the polarity of dynatron of medium, small-power, canal methods that reach function, to detecting for high-power dynatron basically applicable. But, because the working electric current of high-power dynatron is bigger, the area that consequently its Pn writtens guarantee is larger also. Pn bear is bigger, its are retrorse saturated electric current also increases necessarily. So, if resemble measuring dynatron of medium, small-power extremely resistor in that way, the R × 1k of use avometer is blocked measure, the resistance that measures necessarily is very little, seem extremely short circuit is same, use R × normally so 10 or R × 1 block detect high-power dynatron.
3 common Da Lin is in charge of suddenly detect connect what Dalindu is in charge of to detect to general with avometer include to identify electrode, divisional Pnp and Npn type, appraise to measure enlarge ability to wait for a content. Because amount to the E that Lin Du is in charge of - many emissive forms are included between B pole, the R × 10k that should use avometer to be able to offer taller voltage so is blocked undertake metrical.
4 high-power amounts to what Lin Du is in charge of to detect detect the means that Dalindu provides high-power and detect common Dalindu is in charge of basic and identical. But because high-power amounts to Lin Du to was in charge of interior to install V3, R1, R2,wait for protection and component of release leakage current, measure in check so should try these component to distinguish to measuring the effect of data, lest cause a miscarriage of justice. Specific can press narrate a few measure to undertake: A is blocked with 10k of avometer R × measure Pn writtens guarantee between B, C resistance, should measure apparently issue function of report of guide having sheet. , retrorse resistance is due bigger difference. B amounts to Lin Du to be in charge of B in high-power - there are two Pn to written guarantee between E, and receive have resistor R1 and R2. Hold back with avometer report when detecting, when to when measuring, the block value that measures is B - E knot is worth shunt-wound result to block of resistor and R1, R2; When be measured reversely, emissive knot ends, measure those who go out is (the sum of resistor of R1 ＋ R2) , it is hundreds of Europe about, and block cost is fixed, do not hold back along with report alternate and change. But those who need an attention is, some high-power amount to Lin Du canal to be in R1, R2, go up to return and have diode, what measure right now not be (the sum of R1 ＋ R2) , however (R1 ＋ R2) and two diode are worth to the shunt resistance of resistor the sum.
5 take what damp outputs dynatron all right to detect × of avometer park R 1 block, take damp to output dynatron all right through be being measured alone the resistance between each electrode, it is normal to can judge its. Particular test principle, method and move are as follows: A receives red watch pen E, black list pen receives B, be equivalent to measuring high-power to be in charge of B right now - the equivalent diode that E writtens guarantee and the block after protective resistor R is shunt-wound are worth, as a result of equivalent diode to resistor lesser, and the block cost that protects resistor R is average only also 50 of 20 ～ , so, the block value after both is shunt-wound is lesser also; Conversely, the exchange that express a pen, namely red watch pen receives B, black list pen receives E, what measure is high-power canal B - the retrorse resistance of diode of E knot equivalent and the shunt-wound block value that protect resistor R, because equivalent diode is retrorse resistance is greater, so, the block value that measures right now is the value that protects resistor R namely, this value is lesser still. B receives red watch pen C, black list pen receives B, be equivalent to measuring the high-power inside the canal to be in charge of B right now - of diode of C knot equivalent to resistor, the block value that measures commonly is lesser also; the red, black exchange that express a pen, be about to red watch pen receives B, black list pen receives C, be equivalent to measuring the high-power inside the canal to be in charge of B - the retrorse resistor of diode of C knot equivalent, measures block value is infinity normally. C receives red watch pen E, black list pen receives C, be equivalent to measuring the retrorse resistance of diode of the damp inside the canal, measures block cost is average bigger, be more than 300 Europe; the red, black exchange that express a pen, namely red watch pen receives C, black list pen receives E, be equivalent to measuring diode of the damp inside the canal to resistor, measures block cost is average lesser, about a few Europe reach a few Europe .
