4、capacitor
①、appearance inspection
Testing method:
Visual inspection whether the appearance of capacitor expansion, burst.if it was,that means the
capacitor fail.
②、check by open circuit
Testing method:
Check the capacitance by multimeter,If the pointer could swing to the right at once,then the pointer
slowly reset to 0.that means the capacitance is no problem.if the pointer does not move or do not
reset,means capacitance is open circuit, electrolyte dry, or short-circuit
③、capacitance breakdown,leakage of electricity
Testing method:
Check the capacitance by multimeter,If the pointer couldthen the pointer can’t move.that means the
capacitance is breakdown or leakage of electricity
④、Loss tangent inspection (as understanding project)
Judge standard:
run about 10 minutes,check surface temperature of capacitance.If the surface temperature exceeds
the ambient temperature about 15 ℃,that means loss tangent has exceeded the limitvalue 0.0018.
⑤、Check capacitance
check by pointer type multimeter: if the pointer oscillation amplitude is bigger than the standard
capacitance,that means capacitance has been attenuated.
Digital Multimeter:check by Cx interface,the capacity should not exceed the nominal capacity of ±
5%.
⑥、Insulation inspection
Testing method:
normally,the resistance of capacitance is ∞, if the number of resistance is thousands of ohms or
greater, that means capacitance is no problem. if the resistance is smaller or 0,that means capacitance
has been damaged, should be immediately replaced.
5、transformer
1)、Visual inspection
check whether the appearance of transformer burnt phenomenon, check whether has the burnt
transformer smell. If the appearance of burnt yellow phenomena or had burnt smell, transformer
winding is bad.
2)、Check on running
Testing method:
make transformer running under load (which can run with PCB),should be running smoothly, there
shouldn’t be unusual noise. if there is unusual noise,it is multi-electromagnetic noise.
3)、Electrical Characteristics
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