Capacitance breakdown characteristic reachs maintenance

Capacitance damages caused trouble is highest in electronic equipment, among them especially in order to electroanalysis the attaint of capacitance is most common. Capacitance damages expression is: Capacity decrescent; loses short circuit of; of capacity; leakage of electricity completely.

The effect that capacitance has in circuit is distinct, the trouble that cause also has a characteristic each. Circuit board accuses in labour in, digital circuit holds great majority, capacitance is multi-purpose make wave of power source filter, with the capacitor that makes signal coupling and oscillating circuit less. Use in switch power source to electroanalysis mediumly if capacitance damages, criterion switch power source may not rise brace up, without voltage output; perhaps outputs voltage filter wave bad, circuit because voltage is flabby and produce logistic disorder, expression is machine job stand or fall or cannot leave machine, if capacitance is in the power source of digital circuit between negative pole, breakdown expression is Alexandrine.

This is in computer advocate board on expression especially apparent, a lot of computer used a few years to appeared not to leave sometimes machine, the phenomenon that can switch on the mobile phone again sometimes, open box, often can see have electroanalysis the appearance that capacitance beat includes, if tear open capacitance,come down to estimate a size, discovery wants than real value a lot of lower.

The life of capacitance and environmental temperature are concerned directly, environmental temperature is higher, capacitance life is briefer. This rule not only applicable electroanalysis capacitance, capacitance of applicable also other. Answer to examine the electric capacity that leans nearlier with heat source mainly when searching breakdown capacitance so, be like high-power of carbon fin take up yuan the capacitance by parts of an apparatus, closer from its, the possibility of attaint is larger.

Once had built the power supply of smooth flaw detector of a X, user report has smoke to appear from power source come, the large electric capacity that a 1000uF/350V discovers after tearing open a box has oleaginous and same thing to flow, tear open come down to measure a capacity to have a few UF only, still discover only the carbon fin of this capacitance and rectification bridge leaves the nearliest, the in good condition nondestructive that other leaves far, the size is normal. Have the case of ceramics capacitance occurrence short circuit additionally, also discover capacitance leaves calorific component closer. Answer to emphasize particularly on somewhat when the overhaul is searched so.

Some capacitance leakage of electricity is more serious, point to to the hand can be warmed even when feeling with the hand, this kind of capacitance must change.

When the breakdown that overhauls stand or fall, eliminated to contact undesirable possibility beyond, general much is the trouble that capacitance attaint causes. Be in so when encountering this kind of trouble, can check capacitance key, change the person often makes surprizing after capacitance.

The characteristic that resistor damages and differentiate

Often see a lot of abecedarian are when overhauling circuit on resistor do sth over and over again, it is to tear open be solder, be repaired more actually, you should understand the attaint characteristic of resistor only, need not expend Zhou Zhang greatly.

Resistor 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.

List the characteristic that go out according to above, we can observe low block is worth resistor to burn black mark on circuit board first, open a way of the great majority when damaging according to resistor again or block value greaten and the characteristic that resistor of tall block value damages easily, we can be with avometer on circuit board the block of two end is worth the resistance that estimates tall block value directly first, if measure the value that get block to compare nominal block value is great, criterion this resistor damages for certain (the ability after should noticing value waiting for block shows stability makes conclusions, component of because circuit is medium possible shunt-wound capacitance, one fills discharge process) , if measure the value that get block to compare nominal block value is little, need not pay attention to it commonly. Such is in on circuit board each resistor is measured, although " the fault is killed " 1000, also won't let off.

Differentiate of operation amplifier stand or fall

The person that the differentiate of operation amplifier stand or fall is maintained to electron of quite a few has certain difficulty, not merely the relation of literacy rate, discuss jointly in this and everybody, hope to be helped somewhat to everybody.

Ideal operation amplifier is had " empty is short " and " empty is broken " characteristic, the carry discharge means that linear of analyse of these two characteristic bisect uses is very useful. To make sure linear is applied, carry is put must be in closed circuit (negative feedback) next jobs. If do not have negative feedback, the carry below open loop enlarge is put become a comparator. If want to judge the stand or fall of parts of an apparatus, should distinguishing Hunan parts of an apparatus first is in circuit do amplifier to use or do comparator to use.

According to the principle with amplifier short empty, that is to say if if job of this operation amplifier is regular, its are carried to the input together and input end reversely voltage is inevitable and equal, although have the difference also is Mv class, it is of course in circuit of impedance of certain tall input, the internal resistance of avometer can check to be affected a bit to voltage, but also won't exceed 0.2V commonly, if have the difference of 0.5V above, criterion amplifier needs bad undoubted! (I am used FLUKE179 avometer)

If parts of an apparatus is to do comparator to use, allow to be carried to the input together and input end to differ reversely. With to voltage > retrorse voltage, output voltage to be close to maximum; is the same as to voltage < retrorse voltage, the maximum that output voltage to be close to 0V or loses (inspect double power source or) of only power source. If detect,voltage does not accord with this regulation, criterion parts of an apparatus needs bad undoubted! Such you need not use era to change a way, need not tear open chip on circuit board to be able to judge the stand or fall of operation amplifier.

SMT component checks small doohickey

Some stick a component very petty, when with common avometer the test that express a pen is overhauled very no-go, it is to cause short circuit easily, 2 it is the circuit that has insulation coat to besmear board the metallic part of pin of component of disadvantageous bring into contact with. Here tells everybody a simple method, can give detect bring many convenience.

Take two most the needle sewing the garment of trumpet, will rely on to tighten with avometer pen, take a many next a fine copper cash in cable, the watch with fine copper cash the pen is mixed the needle that sew the garment is bound together, weld of reoccupy soldering tin. Use the anxiety that short circuit does not have again when containing petty and pinpoint watch pen to measure those SMT component so, and pinpoint and OK thorn defeats insulation coating, pound crucial position continuously, again also need not would you mind goes blowing those velar film.

Short circuit of common power source is overhauled

In circuit board maintenance, if encounter the trouble of short circuit of common power source often the head is big, because a lot of parts of an apparatus are common same power source, each parts of an apparatus that uses this power source has the suspicion of short circuit, if board go up component is not much, use " v hoe the earth " means in the end can find short circuit place, if component is too much, "V hoe the earth " can be about to lean lot to the state v hoe. Recommend the method that compares a canal to use here, use this method, get twice the result with half the effort, often can find breakdown place very quickly.

Want to have the power supply with all adjustable electric current of a voltage, voltage 0-30V, voltaic 0-3A, this power source is not valuable, 300 yuan or so. Move open circuit voltage level of tension of power source of parts of an apparatus, move electric current to first the smallest, if the 5V of 74 series chip and 0V are carried,the power source tension that increases this tension in circuit is nodded, inspect short circuit degree, increase electric current slowly, feel parts of an apparatus with the hand, should feel a certain parts of an apparatus calorific and apparent, this often is the component of attaint, but will get off to be measured further affirm. Scarcely of the voltage when be being operated of course can exceed the working voltage of parts of an apparatus, and cannot be received turn over, can burn out otherwise the parts of an apparatus with good other.

Rubber solves big problem

The board card that industrial control uses is increasing, a lot of board card uses golden finger to thrust the way that inserts groove. Because industrial spot environment is harsh, the much dirt, damp, environment that corrodes gas more makes board card generation contacts undesirable breakdown easily, a lot of friends are likely through changing the means of board card solved a problem, but the expense that buys board check is very considerable, especially the board card of certain entrance equipment. Actually everybody mights as well use rubber is brushed brush a few times repeatedly on golden finger, after the contamination that gets on golden finger clears clean, retry machine, did not solve a problem definitely! The method is simple practical.

Electric breakdown is analysed

All sorts of stand or fall are electric breakdown tells from probability magnitude include the following kinds of cases probably:

1, the contact is undesirable

When when interior of as undesirable as the contact that insert groove, cabled yarn breaks off, board card is connected, be illogical, line outlet and wiring terminal contact are bad, yuan solder of empty of parts of an apparatus all belong to this kind of;

2, signal suffers interference

logarithm word circuit, below specific circumstance requirement, breakdown just can appear, it is to disturb too big impact really likely control system makes its make mistake, also have circuit board specific element parameter or integral expression parameter appeared to change, make incline to of interference rejection ability bit more critical, appear thereby breakdown;

3, yuan thermal stability of parts of an apparatus is bad

From the point of many maintenance practice, among them head push electroanalysis the thermal stability of capacitance is bad, it is the; such as other capacitance, dynatron, diode, IC, resistor next

4, on circuit board wettish, dust

Damp and dirt retention will be electric, have resistance effect, and bilge in heat cold value of the block in the process that shrink still can change, this resistance has shunt-wound effect jointly with other component, circuit parameter can be changed when this result is stronger, make breakdown produces;

5, software also is one of consideration elements

A lot of parameter in circuit use software to adjust, the abundant quantity of certain parameter is moved too lowly, be in critical limits, accord with software to decide when machine operating conditions when the reason of breakdown, so call the police to be able to appear.

Capacitance breakdown characteristic reachs maintenance

Capacitance damages caused trouble is highest in electronic equipment, among them especially in order to electroanalysis the attaint of capacitance is most common. Capacitance damages expression is: Capacity decrescent; loses short circuit of; of capacity; leakage of electricity completely.

The effect that capacitance has in circuit is distinct, the trouble that cause also has a characteristic each. Circuit board accuses in labour in, digital circuit holds great majority, capacitance is multi-purpose make wave of power source filter, with the capacitor that makes signal coupling and oscillating circuit less. Use in switch power source to electroanalysis mediumly if capacitance damages, criterion switch power source may not rise brace up, without voltage output; perhaps outputs voltage filter wave bad, circuit because voltage is flabby and produce logistic disorder, expression is machine job stand or fall or cannot leave machine, if capacitance is in the power source of digital circuit between negative pole, breakdown expression is Alexandrine.

This is in computer advocate board on expression especially apparent, a lot of computer used a few years to appeared not to leave sometimes machine, the phenomenon that can switch on the mobile phone again sometimes, open box, often can see have electroanalysis the appearance that capacitance beat includes, if tear open capacitance,come down to estimate a size, discovery wants than real value a lot of lower.

The life of capacitance and environmental temperature are concerned directly, environmental temperature is higher, capacitance life is briefer. This rule not only applicable electroanalysis capacitance, capacitance of applicable also other. Answer to examine the electric capacity that leans nearlier with heat source mainly when searching breakdown capacitance so, be like high-power of carbon fin take up yuan the capacitance by parts of an apparatus, closer from its, the possibility of attaint is larger.

Once had built the power supply of smooth flaw detector of a X, user report has smoke to appear from power source come, the large electric capacity that a 1000uF/350V discovers after tearing open a box has oleaginous and same thing to flow, tear open come down to measure a capacity to have a few UF only, still discover only the carbon fin of this capacitance and rectification bridge leaves the nearliest, the in good condition nondestructive that other leaves far, the size is normal. Have the case of ceramics capacitance occurrence short circuit additionally, also discover capacitance leaves calorific component closer. Answer to emphasize particularly on somewhat when the overhaul is searched so.

Some capacitance leakage of electricity is more serious, point to to the hand can be warmed even when feeling with the hand, this kind of capacitance must change.

When the breakdown that overhauls stand or fall, eliminated to contact undesirable possibility beyond, general much is the trouble that capacitance attaint causes. Be in so when encountering this kind of trouble, can check capacitance key, change the person often makes surprizing after capacitance.

The characteristic that resistor damages and differentiate

Often see a lot of abecedarian are when overhauling circuit on resistor do sth over and over again, it is to tear open be solder, be repaired more actually, you should understand the attaint characteristic of resistor only, need not expend Zhou Zhang greatly.

Resistor 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.

List the characteristic that go out according to above, we can observe low block is worth resistor to burn black mark on circuit board first, open a way of the great majority when damaging according to resistor again or block value greaten and the characteristic that resistor of tall block value damages easily, we can be with avometer on circuit board the block of two end is worth the resistance that estimates tall block value directly first, if measure the value that get block to compare nominal block value is great, criterion this resistor damages for certain (the ability after should noticing value waiting for block shows stability makes conclusions, component of because circuit is medium possible shunt-wound capacitance, one fills discharge process) , if measure the value that get block to compare nominal block value is little, need not pay attention to it commonly. Such is in on circuit board each resistor is measured, although " the fault is killed " 1000, also won't let off.

Differentiate of operation amplifier stand or fall

The person that the differentiate of operation amplifier stand or fall is maintained to electron of quite a few has certain difficulty, not merely the relation of literacy rate, discuss jointly in this and everybody, hope to be helped somewhat to everybody.

Ideal operation amplifier is had " empty is short " and " empty is broken " characteristic, the carry discharge means that linear of analyse of these two characteristic bisect uses is very useful. To make sure linear is applied, carry is put must be in closed circuit (negative feedback) next jobs. If do not have negative feedback, the carry below open loop enlarge is put become a comparator. If want to judge the stand or fall of parts of an apparatus, should distinguishing Hunan parts of an apparatus first is in circuit do amplifier to use or do comparator to use.

According to the principle with amplifier short empty, that is to say if if job of this operation amplifier is regular, its are carried to the input together and input end reversely voltage is inevitable and equal, although have the difference also is Mv class, it is of course in circuit of impedance of certain tall input, the internal resistance of avometer can check to be affected a bit to voltage, but also won't exceed 0.2V commonly, if have the difference of 0.5V above, criterion amplifier needs bad undoubted! (I am used FLUKE179 avometer)

If parts of an apparatus is to do comparator to use, allow to be carried to the input together and input end to differ reversely. With to voltage > retrorse voltage, output voltage to be close to maximum; is the same as to voltage < retrorse voltage, the maximum that output voltage to be close to 0V or loses (inspect double power source or) of only power source. If detect,voltage does not accord with this regulation, criterion parts of an apparatus needs bad undoubted! Such you need not use era to change a way, need not tear open chip on circuit board to be able to judge the stand or fall of operation amplifier.

SMT component checks small doohickey

Some stick a component very petty, when with common avometer the test that express a pen is overhauled very no-go, it is to cause short circuit easily, 2 it is the circuit that has insulation coat to besmear board the metallic part of pin of component of disadvantageous bring into contact with. Here tells everybody a simple method, can give detect bring many convenience.

Take two most the needle sewing the garment of trumpet, will rely on to tighten with avometer pen, take a many next a fine copper cash in cable, the watch with fine copper cash the pen is mixed the needle that sew the garment is bound together, weld of reoccupy soldering tin. Use the anxiety that short circuit does not have again when containing petty and pinpoint watch pen to measure those SMT component so, and pinpoint and OK thorn defeats insulation coating, pound crucial position continuously, again also need not would you mind goes blowing those velar film.

Short circuit of common power source is overhauled

In circuit board maintenance, if encounter the trouble of short circuit of common power source often the head is big, because a lot of parts of an apparatus are common same power source, each parts of an apparatus that uses this power source has the suspicion of short circuit, if board go up component is not much, use " v hoe the earth " means in the end can find short circuit place, if component is too much, "V hoe the earth " can be about to lean lot to the state v hoe. Recommend the method that compares a canal to use here, use this method, get twice the result with half the effort, often can find breakdown place very quickly.

Want to have the power supply with all adjustable electric current of a voltage, voltage 0-30V, voltaic 0-3A, this power source is not valuable, 300 yuan or so. Move open circuit voltage level of tension of power source of parts of an apparatus, move electric current to first the smallest, if the 5V of 74 series chip and 0V are carried,the power source tension that increases this tension in circuit is nodded, inspect short circuit degree, increase electric current slowly, feel parts of an apparatus with the hand, should feel a certain parts of an apparatus calorific and apparent, this often is the component of attaint, but will get off to be measured further affirm. Scarcely of the voltage when be being operated of course can exceed the working voltage of parts of an apparatus, and cannot be received turn over, can burn out otherwise the parts of an apparatus with good other.

Rubber solves big problem

The board card that industrial control uses is increasing, a lot of board card uses golden finger to thrust the way that inserts groove. Because industrial spot environment is harsh, the much dirt, damp, environment that corrodes gas more makes board card generation contacts undesirable breakdown easily, a lot of friends are likely through changing the means of board card solved a problem, but the expense that buys board check is very considerable, especially the board card of certain entrance equipment. Actually everybody mights as well use rubber is brushed brush a few times repeatedly on golden finger, after the contamination that gets on golden finger clears clean, retry machine, did not solve a problem definitely! The method is simple practical.

Electric breakdown is analysed

All sorts of stand or fall are electric breakdown tells from probability magnitude include the following kinds of cases probably:

1, the contact is undesirable

When when interior of as undesirable as the contact that insert groove, cabled yarn breaks off, board card is connected, be illogical, line outlet and wiring terminal contact are bad, yuan solder of empty of parts of an apparatus all belong to this kind of;

2, signal suffers interference

logarithm word circuit, below specific circumstance requirement, breakdown just can appear, it is to disturb too big impact really likely control system makes its make mistake, also have circuit board specific element parameter or integral expression parameter appeared to change, make incline to of interference rejection ability bit more critical, appear thereby breakdown;

3, yuan thermal stability of parts of an apparatus is bad

From the point of many maintenance practice, among them head push electroanalysis the thermal stability of capacitance is bad, it is the; such as other capacitance, dynatron, diode, IC, resistor next

4, on circuit board wettish, dust

Damp and dirt retention will be electric, have resistance effect, and bilge in heat cold value of the block in the process that shrink still can change, this resistance has shunt-wound effect jointly with other component, circuit parameter can be changed when this result is stronger, make breakdown produces;

5, software also is one of consideration elements

A lot of parameter in circuit use software to adjust, the abundant quantity of certain parameter is moved too lowly, be in critical limits, accord with software to decide when machine operating conditions when the reason of breakdown, so call the police to be able to appear.