crt显示器消磁继电器不断吸合（CRT display degaussing relay continuously attract）

crt显示器消磁继电器不断吸合（CRT display degaussing relay continuously attract） crt显示器消磁继电器不断吸合(CRT display degaussing relay continuously attract) Samsung 788DF, 763MB, 765MB and other models of the display, there is a common fault is CPU, intermittent work relay flip-flop. The failure of machine CPU pin has a AFC SENS signal, normal working voltage of this end to about 5V, what is more likely to be determined by the internal data (guess), but the signal from the output transformer, so this will involve a series of problems, when the working conditions of line output an abnormal will occur when the signal is not normal, I have tried to remove the board when the plug, remove the two power, do not plug deflection will cause CPU intermittent work relay flip-flop. What is the reason for it, and later through the efforts of circuit found that as long as the CPU voltage AFC at the moment of starting up to 5V will protect work. Since the problem has been discovered, how to solve the problem has become a new subject. After a morning study, we have finally found a solution, as follows: 1, with a 4 thousand and 700 ohm resistor connected to the +5V and CPU AFC feet 2, disconnect the two power supply (remember to prevent the two power supply is not normal, cause unnecessary loss), 3, you can begin to check as you please. 4, after the removal of the resistance to add, after all, this design has its advantages. We also found a problem that the original drawings of the R531 resistance is 56 thousand ohms, and the actual application of 82 thousand in Europe, built a case of people sentenced to death of the machine, check the components basically intact, the resistance change and repair for 56 thousand euro. It is estimated that the difference between the parameters of the components such as the feed pipe and the original machine element causes the AFC voltage to be low. SONY KV-F29MFlJ three repeatedly pull fficeffice "/ > degaussing relay After starting, no grating, no image, no sound, degaussing relay repeatedly attract. The fault may occur in the I2C bus control system and the control circuit. When checking, turn on the machine cover, check the data line SDA and the SCI- voltage of the clock line with oscilloscope and multimeter, and find that the SDA voltage is reduced from the normal 5V to 3V. SCI. The voltage is normal, so the voltage of the data line is judged to be lower by a certain IC. The data line turn off each controlled I2C, disconnect the IC202 relay, no longer pull, with a multimeter measuring IC202 power supply terminal (15), (16) found no feet, +9V power supply, the examined for fracture of printed circuit board. After re welding, the machine troubleshooting. The S correction circuit has no fault, the S correction capacitor and the field effect module are all in good condition. Short circuit TIP122 C-E can boot for a while but about ten seconds after the screen flashes, damping diode serious fever. Disconnect the high voltage packet +B input and connect the bulb at the first power supply. The main power supply can work properly. I wonder if the high pressure package has problems, \r\n this article from: [Chinese appliance maintenance alliance] [], reproduced please indicate the source! Disconnect TDA9118 24 feet EW-OUT boot, you can also display a picture. During the period of adjustment for non response amplitude, TDA9118 has replaced the fault unchanged, two power not to signal measured at 150V, with two 800X600@85Hz voltage is 160V, the two sense voltage is too high, the strange thing is for tube actually do not burn, but also not what temperature. The high pressure bag is broken I just finished a LG 15 yesterday, the phenomenon is basically the same as yours, but I have a fault of 2 y, S$^) H; a: o Power primary electrolytic capacitor C911 leakage leads to secondary power supply high protection, voltage fluctuation. CPU repeated power to cause the degaussing relay to repeatedly suck and. And not some experts do not look at, tell the package bad. You should first let the power can work normally (off line load, high fault) if the power normal high packet high-voltage fault is higher but not every time bad, off line load, false load in the +B power supply, start the test, I was taking a power +B the output diode short circuit will cause the phenomenon, you should know the problem is above the line circuit in power supply or power supply. The output voltage instability, check the power supply, then the load is disconnected to detect the output voltage is very easy to find the point of failure. Shenzhen produced PLUTO-1775X power on, the indicator light flashing red light, the display without the relay after the degaussing sound finishing date: 2008-2-10 10:26:22 data editing: click the number: Overhaul process: after opening the cover, it is found that the pipe C5449 has been broken down and short circuited. After changing the pipe line, the electrify machine is still flashing red light. The output voltage of the two power supply is 55V, and the B pulse of the pipeline is zero. The line drives the drive tube C with no 12V voltage. Along the 12V power circuit it is found that the LA7512 input has no 15V voltage, but the secondary of the switching power supply has the 15V power output. Through careful observation of the circuit, it is found that the input of the LA7812 is between the input of the CPU and the switching power secondary 15V, and there is a switching triode controlled by the transistor. The measurement shows that the tube is in the end state. Circuit analysis found that CPU did not issue boot instructions. By flashing the red light after the boot, it shows that the CPU has been working. Check the required hardware conditions for CPU without exception. Finally, suspect CPU or memory 24C04 may be abnormal, the CPU and memory of this machine are all socket, so it is very convenient to replace. Because it is in the second-hand computer shop repair, by the way to open the same type of machine can work properly, the replacement of CPU invalid, the contemporary change memory 24C04 after the machine work properly. This display memory abnormalities caused by the fault phenomenon, and the color TV memory abnormalities caused by the fault phenomenon is different, so in the maintenance, I made a lot of detours. If no memory replacement for this model occurs, I will not be able to fix this monitor. From this example, you can see whether the memory and its data are normal or not, and it is also one of the necessary conditions for CPU to work properly. Today, a Samsung 743DF_S (AV17KUBL/XSF) receiver is being repaired. The original fault is not connected. Open the cover, that is the power of synchronous pulse transformer ignition 300V power rectifier filter after the copper foil has been burned, after cleaning, measuring the fuse has been broken, the power block DP904 no short circuit after power supply block did not work, no bad check peripheral components, judge DP904 has been bad, because do not have DP904 and DP104 substitution, the phenomenon of degaussing circuit breaker "tick" constantly absorbing and releasing the power on. The measurement of the power output voltage changes with secondary fluctuations were tick "sound, while using the oscilloscope measurement base line output tube has a waveform, sometimes not just. Estimation of DP104 can not be used in this circuit, and then hand on some DP704 to generate electricity substitution, or the same phenomenon, but to the market to buy a piece of power DP904, installed after the boot, or the same phenomenon! Had to go through the QQ and colleagues for help, saying that the power block next to a small capacitor is not good, so simply do not use it (remove), but still not! Because the power supply has no obvious short circuit phenomenon, it is very good to measure the AFC end wave of the high voltage package with oscillograph. Only found that the problem is still on the DP904, and buy a DP906 power block, power OK! The monitor screen shows "check the signal line."". Looking back, there may be quality problems with the DP904 bought back. 1, DP104 and DP704 are not available on the DP904 circuit. 2, DP906 can replace several power blocks above