What the power source majority in monitor uses nowadays is switch regulated power supply (abbreviation switch power source) . So-called switch power source, it is to show the adjustment in switch power source is in charge of the job to be in end area and saturated area. When adjusting a canal to end, be equivalent to mechanical switch disconnect, when adjusting tubal saturation, be equivalent to mechanical switch closing. This kind of step aside closes the dynatron of action, call switch the canal, and the power source that with switch the canal stabilizes voltage, it is switch regulated power supply with respect to what say. Common breakdown is the breakdown of switch power source mostly in monitor. Differentiate by switch power source and laden connection means, switch power source can be divided for series connection model with paralell connection model two kinds. The output end of power source of series connection switch adjusts canal and rectification diode to be linked together with electrified wire netting directly through switch, reason its motherboard is electrified, common says " hot motherboard " , bring very big safe question to maintenance, everybody is being torn open machine when want to notice; And power source of paralell connection switch, between its output end and communication 220V electrified wire netting by switch transformer 2 side, side are undertaken keeping apart, because this is overall on circuit board besides the place that with switch transformer side is linked together, fang Jun of the others ground is not electrified, friend call his " cold motherboard " . Security of power source of paralell connection switch is good, but its circuit is relatively complex, the demand that provides to switch is higher, if protects circuit job status to be not stabilized, the breakdown of generation is relatively serious also. Maintaining switch power supply is the key in monitor maintenance (the 70 ％ that occupy monitor to maintain a volume in daily maintenance are controlled) with difficulty. Transformer of a segregation had better be joined when maintaining switch power supply, because ground connection end is electrified,it can avoid to build the accident that gets an electric shock into personnel. To 14 inches of monitor to 17 inches, the segregation transformer that uses 70W ～ 100W is enough. Step-down can be used to overhaul a law when maintaining switch power supply. Its method is: Plug receives the power source monitor to go up in an AC voltage regulator, move the output voltage of voltage regulator to 100V left and right sides again, next electrify overhaul, and successive raises power source voltage to overhaul. Breakdown example one: Switch on the mobile phone to burn out safe, output voltage is 0. Because switch is in charge of,this kind of circumstance is commonly by puncture, blast off extremely cause with place of collector short circuit. Can tear open switch canal first right now below, measure its to blast off extremely be opposite with collector terrestrial electricity block, if be 0 or very small, change can. But also should check next other yuan parts of an apparatus has without the problem rear can switch on the mobile phone. Breakdown example 2: Grating appears " S " the twist of form. This kind of problem should check filter wave circuit and stabilized voltage circuit mainly, because have open circuit of a diode,be commonly, by Quan Bo rectification becomes half commutate, this also may be capacity of capacitance of its filter wave reduces be caused by. Breakdown example 3: Communicate breakdown of sex of occurrence short circuit of circuit of wave of 220V commutate filter, and switch on the mobile phone burn insurance. Check rectification diode to have first without capacitance of wave of short circuit, filter whether serious leakage of electricity. Still can extract degauss coil outlet, check looks up degauss thermal resistor to have without breakdown of short circuit sex, if have,should change new. Breakdown example 4: Switch on the mobile phone without grating, without show, power source indicator light is not bright, but did not burn insurance. Should check transformer of communication mutual inductance at this moment whether the current limliting resistor of circuit of open circuit, commutate has without open circuit (burn) invalidation, or whether does rectification diode open circuit. Breakdown example 5: Without grating, without show, and unusual noise is given out inside machine. If give out " Zhi Zhi " sound, explain oscillation frequency is low, should examine the cell that concerns with oscillation, if give out " Da Da " sound, explain power source sheds protection too, should have checked shed protective circuit. Breakdown example 6: Output voltage prep above or under normal value. Output voltage tower above or under normal value ten bend over arrive a few bend over, but do not be again 0, protect circuit also not movement. At this moment breakdown phenomenon will change along with voltage and circumstance each different, can adjust stabilized voltage potentiometer, if output changeless or change is very little, with respect to demonstrative sampling poor discharge road has trouble, offer fiducial stabilized voltage diode among them by the possibility of puncture or short circuit very big.
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