One, three, power fuse

This phenomenon shows that the rectifier converter circuit and the switching power supply has short circuit fault. Repair, unplug the connector CN2607 first and the D plate connected, packed with the specifications of the power supply fuse tube (4a) and re energized, if continue around power fuse, usually bridge rectifier D2600 breakdown; if electricity, no longer burning fuse, measuring the CN2607 4 and 6 terminal voltage, is often should 300V DC voltage. If the voltage of up to 600V, is usually a conversion integrated block IC2601 second, 3 pin internal double diode breakdown damage or D2601, C2611 and other undesirable. If the investigation found IC26012, 3 feet short circuit damage without the same type integrated block replacement, and user grid voltage above 160V, detachable to IC2601, R2607, C2612, as emergency treatment. Note: when the grid voltage is 220V, IC26012, 3 feet short, connector CN2607 4 and 6 between the two ends of the voltage will more than 600V, tend to make the switch regulated power supply integrated block IC601 internal switch breakdown. Therefore, after the overhaul of the complete flow conversion circuit, IC601 and its peripheral components should be carefully checked. If there were no abnormal circumstances, the CN2607 and D board CN0525 connector plug, keeps electric test machine.

Two, three, a power fuse intact, and power indicator light is not always bright

This phenomenon is generally caused by the switching voltage regulator power supply damage or short circuit load caused by. When the repair, the first open line load (disconnect the end of the L606), and the B output port on the ground to the false load (C616 ends). If the false load is normal at the end of the load, there is a short circuit fault in the load, and the common line output tube is damaged. If the false load voltage is 0V, the detection switch power supply integrated block IC6011 pin and 9 pin voltage, if the 1 pin voltage is 0V, usually because of the IC601 internal switch tube C, e electrode breakdown damage, resulting in limited flow insurance resistance R611. If it is found that the IC601 internal switch breakdown, can not only replace IC601 and R611 will pass electrical test machine, check further even q600, D601, such as whether it is normal; if the measured IC6011 pin voltage is about 300V, test-retest IC6019 pin voltage. If 0V, should check connector CN05251 foot front stage circuit D2605 start components is open; if IC6019 pin voltage of 8V above, then check IC6012 feet of resistance R618. Otherwise suspected IC601 internal oscillator and other circuit damage, should be replaced IC601.

Three, the power supply is switched on, the panel indicator light is extinguished, appeared three

This phenomenon is usually a switching regulator power supply voltage control circuit fault. Maintenance, check on the optocoupler IC600, error amplifier integrated block IC602 components.

Four, the panel standby indicator light. Remote start, standby lights flashing, restored to the steady state, no light, no sound.

This phenomenon is generally the switch mode power supply to enter standby protection state. According to the protection circuit analysis, can be checked by the following steps. The first step: using a multimeter over current sampling resistor line scanning R886 measurement in the power supply circuit resistance. If the 1.2, and then through the power, to measure the voltage drop across the two ends, if the power is greater than 1.5V, which is the line scanning circuit to the flow of the machine into the standby protection state, should check the line scan circuit. AC short circuit fault of common output stage; the second step: monitoring connector of the foot of the CN05061 voltage to the ground, if the boot and the pin voltage is reached over 4.8V should be check zener D1502 whether the breakdown, also should check over-current protection circuit of triode Q803 and bias is normal. If the investigation is not abnormal, that is because of the tube caused by the high anode voltage. Focus on examination of line retrace capacitance; the third step: monitoring connector of the foot of the CN05066 to ground voltage, boot, if the voltage is much lower than the normal value of 5V, focus on examination of Q1501 to Q1504, composed of field protection circuit and field scanning circuit. Description: the value of the monitored voltage above is instantaneous.

Five, after the boot, the machine is always in standby mode, that is, standby indicator light

This fault is in the exclusion of the protection circuit operation and so that the machine is in standby, the key to check the open / standby control circuit. The first detection of Q603 base potential, in the normal working state of the machine should be about 3.1V. If the potential is too low or 0V, should check the circuit between the Q603 base connector to the foot of the CN5207 to microprocessor IC001{18} feet, including Q603 IC001; if Q603 base potential about 3.1V and test-retest Q603 the collector potential, if higher than 0.7V, determine damage Q603, to be replaced; if Q603 collector voltage of the approximately 0V, and the collector voltage of Q602 far lower than 9V, should check Q602 and other components.