We display screen through VFD of the face plate before machine whether illume, will judge breakdown roughly place.
If receive screen of electrify source VFD not bright, without the graph invalidation of function of breathed and all key, the problem goes in power source loop and CPU control a system (basically point to) of power supply of systematic EVRV 5V.
Receive screen of electrify source VFD to illume, all key function loses action, without the graph breathed, demonstrative switch power source already oscillation power supply, CPU controls a system to also finish restoration to enter regular job, the problem goes in power source circuit of 2 power supply.
Switch power source cannot the reason of oscillation is very much: It is interior of Q803 of thick film circuit the function is perfect, but the exterior condition that self-oscillation place requires not all ready, short circuit of circuit of wave of common commutate filter; Power source starts resistor metamorphism be no longer in force; Job of road of feed of positive and negative is unusual. 2 it is invalidation of in-house function of Q803 of thick film circuit, common switch provides breakdown.
Examination fuse F801 is burned, model of Q803 of thick film circuit seals exterior level off bright and clean, its 4 feet flow too detect layer of lacquer of resistor R808 surface retains the primary colors, brightness that cite a base, criterion F801 fusing reason is in circuit of rectification filter wave. One of D805 of ～ of D802 of canal of common bridge-type commutate are retrorse puncture or leakage of electricity, puncture of C805 of filter wave capacitance or leakage of electricity; Surface of Q803 of thick film circuit is raised, flow too detect layer of lacquer of resistor R808 surface is brown, the solder that cite a base nods oxidation to blacken, show Q803 has damaged.
Measure so that C805 of filter wave capacitance is carrying voltage to be 300V, exclude power supply loop short circuit. Switch on the mobile phone to monitor Q8034 foot voltage for an instant, if express head finger to appear to after beating, answer 0, explain switch power source has oscillation capacity, as a result of laden short circuit, switch canal sheds protection too compulsive power source accuses to stop since circuit brace up. E of ～ of C of dynatron of the photosensitive inside 3 feet of opto-coupler Q8024 ～ extremely serious leak or puncture, also should appear similar stop brace up problem.
The finger that express a head is not had jumpy it is from beginning to end 0, explain condition of power source self-oscillation is insufficient, the key checks the D807 in loop of make a present of of R804 of the resistor that start, positive and negative, R805.
Canal of switch of interior of thick film circuit damages the reason basically is: Electrolyte of C805 of filter wave capacitance spills over capacity attenuation or invalidation, make the ＋ 300V volts d.c. of output carries many ripple part, equivalent is added in switch canal base relatively substantially pulse of make a present of of positive and negative. When power source starts oscillation, the tension of make a present of of two positive and negative that alternate of switch canal base increases makes collector electric current urgent rise suddenly, and shed circuit of wide modulation of protection and arteries and veins to have not answer a movement too, instantaneous surge electric current already provided switch thermal breakdown. Encounter this kind of situation, must one-time change next filter wave capacitance and thick film circuit to retry.
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