Electronic circuit is medium now, having a lot of trouble is caused by breakdown of switch power source, and in the common breakdown of switch power source, having much again is by a few fragile damage and cause.

 

E.g. , the switch in switch power source is in charge of, regular attaint, but switch transformer, the odds of attaint however dinky! Almost negligible not plan.

 

So the following, I summed up the component of a few easier attaint in switch power source, and what breakdown phenomenon can appear after attaint, share everybody.

 

1. is sure to be in charge of

 

Burning insurance great majority is hind class circuit big electric current is caused, that is to say the circuit from the back has short circuit case, e.g. switch canal, current limliting resistor, the bridge piles burned-out short circuit, chip attaint, attaint of capacitance of great strain wave can be caused etc burn insurance, breakdown phenomenon does not have reaction for electrify. (Sweet clew: After if changed insurance,be in charge of, not rushed electrify checks, must find out breakdown or electrify of the ability after taking certain step)

 

2, filter wave capacitance damages (the large electric capacity of 300V)

 

Leakage of electricity of filter wave capacitance or capacity are reduced, can create dead opportunity or switch on the mobile phone without reaction, attaint of filter wave capacitance can see from the exterior capacitance rouses a bag commonly. (Also have what do not rouse a bag of course)

 

3. outputs filter wave capacitance:

 

Breakdown phenomenon and filter wave capacitance are bad about the same.

 

4. switch is in charge of

 

The a bitth had told, after switch requests damage, general meeting burns insurance, current limliting resistor also can follow to damage, some moment also burn out even PWM chip accordingly (this kind of phenomenon is not much nevertheless) .

 

Since insurance canal was burned, breakdown phenomenon is electrify does not have reaction for certain.

 

5, stabilized voltage diode.

 

Bear in diode place retrorse voltage is more than his nominal below the circumstance that stabilized voltage is worth, stabilized voltage provides can retrorse breakdown, but this kind of puncture can restore, after be being reduced in voltage value namely, stabilized voltage canal can break away from puncture condition, be equivalent to open circuit. If be short circuit, so stabilized voltage canal had damaged, electric current exceeds stabilized voltage canal to bear electric current is caused, for thermal breakdown, not recoverable.

 

6. smooth lotus root and TL431

 

These two component damage general meeting causes output to voltage is not stabilized or be outputted without voltage, how to detect, there is special introduction to pass in the article in front of me (sampling resistor attaint can cause congener problem) likewise.

 

7. starts resistor:

 

The resistor that start is to receive between 300V power source and switch canal base, attaint of the resistor that start can be caused have 300V, but output without voltage, and overall without reaction.

 

Resistor of 8. current limliting:

 

Just as its name implies, this resistor attaint sheds protective circuit job too, with the resistor that start 300V does not have output voltage.

 

9.PWM dominates chip:

 

PWM attaint can be caused have 300V, but still can repeat without output voltage burn switch canal and insurance, right block value can be hit to judge its stand or fall when detecting, be worth to ground block normally be opposite besides its outside lower margin, other bring a foot to have hundreds of ohm.