| Current sense resistor is usually located
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| | power section will blow and
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| in the switch mode power
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| | most of the time the components changed
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| supply section. Newer version of
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| | are fuse, power fet, pwm ic,
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| monitor-the b+ (boost) circuit
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| | zener diode and current sense
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| also have this current sense resistor.
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| | resistor.Do you know that a small change
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| If you repair electronic
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| | in this current sense resistor value
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| equipment especially the switch mode
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| | have a great impact on the secondary
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| power supplies, the current
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| | output? A little change in value
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| sensing resistor is connected to the
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| | say from 0.22 ohm to 0.44 ohm can caused
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| source pin of power FET (field
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| | your ouput voltage to drop
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| effect transistor) and the other end to
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| | into half! I have seen a lot of repairer
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| HOT GROUND. The value of
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| | can't detect this type of
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| current sense resistor is in the range
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| | problem (low output voltage) due to that
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| of 0.1 ohm to about 1 ohm.
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| | they used analog or digital
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| The values are depends on the design of
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| | meter that don't have the low ohms
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| each power supply.In monitor power supply
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| | range. You can't differentiate
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| where pulse width modulation (pwm) ic
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| | if the low ohms resistor has its value
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| UC3842
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| | changed by using normal meters.
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| are used. Pin 3 of this power ic is
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| | I personally use the Dick Smith ESR
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| called I-sense which means
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| | Meter which have the capabilities
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| current sense and this pin is connected
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| | to check resistor value down to 0.01
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| to source pin of POWER FET.
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| | ohm! If you don't have this
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| The purpose of this current sense
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| | special meter you may just direct
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| circuit is for overcurrent protection.
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| | replace the current sense resistor
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| This circuit usually samples the voltage
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| | to see if the generated secondary output
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| drop across a resistor in series
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| | will back to normal voltage.Another tip
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| with the switching fet transistor. If
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| | is that if the current sense resistor in
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| the current rises abnormally due to
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| | the monitor
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| some short circuit in the secondary side
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| | B+ circuit have changed value it will
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| such as a shorted secondary diode
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| | caused the output in the
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| or horizontal output transistor (HOT),
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| | boost circuit to become low and you will
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| the voltage will exceed a reference
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| | have a small width display
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| level and shutdown the pulse generator
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| | and of course the high voltage will
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| which is the PWM ic. This circuit
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| | become low as well. Instead of
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| provides protection to components in the
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| | 24Kv it becomes 15-18Kv.Jestine Yong is
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| event a problem occurs.
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| | a electronic repairer and a writer.
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| In some cases where overload happen-the
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|
