Hard bones! After a week, I finally solved it. - appliance repair - Huaqiang Electronic Network

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

SMD aluminum electrolytic capacitor

MOS power IC full range

The article is a bit long, everyone will be a novel!

The machine is Xoceco LC-32U19, the fault is not boot, this is for a second-hand home appliance owner to repair, disassemble to see the power board has 4 5 capacitor drum kit, after the boot is normal, I thought this counted to one Taiwan, he gave it to the boss. Who knows for a while, the boss said that the TV sold to the user, the user said that there is a problem, and returned, I have a problem with this test, sometimes can boot and sometimes can not boot, repeated trials are so, it seems that there are Trouble, get back to the store for detailed observation, when the test machine found a phenomenon, if you hear the horn slamming when you turn off the power, then turn it on and turn it on. Only the shell is checked. The machine consists of a power board, a logic board, a motherboard, a video converter board, and a high voltage board. The power board can be checked without problems, and the logic version is not likely. The video converter board can be disconnected by a plug. Open, can also be ruled out, the fault is basically locked and then the motherboard and high-voltage board, but the possibility of the motherboard is relatively large, so focus on the inspection on the motherboard. Firstly, measure the voltage across the motherboard is normal, replace the 1.2V, 3.3V 1117 DC conversion block, invalid, and then replace all the capacitors around it or no results, consider the fault sometimes good or bad, whether there is a problem of solder joint ? So the MCU super large-scale chip repair welding, the fault remains, and then repair the surrounding DDR two buffers or the sound of the waves is still a bit, so the head is a bit big, so I put aside and go. After two days of checking again, it was found that the TV could be turned on for the first time, and the second time it was turned off, it could not be opened. It only took 10 minutes to open. This time, we must consider the high-voltage board. Can it be a high-voltage protection caused by poor lamp? So the high-voltage board is de-protected. After the processing is finished, it can be opened for the first time. It can be turned on or off again. I can’t really get it. I have the idea of ​​giving up, but I have already considered the money. I gave up this idea again. I don't know if other people have my idea. If the money goes into the pocket, I don't want to go out. If I don't collect the money, I will definitely send it back to him. Don't waste my brain cells. Now There is no passion for picking up the night battle when you are young. He threw another side. After another two days, I picked up again. This time I thought about whether there is still the possibility of soldering on the motherboard. Decided to follow the idea to carry out maintenance, set up the TV, when the second time does not boot, press the motherboard to see the screen and see if there is a reaction, press the button, the miracle appears, the screen suddenly lights up, excited to stand up immediately However, there is no boot screen, no characters, only dark rasters. What is the situation? Quickly find out which part to press? It was a random press, and finally found that when the MCU main chip was pressed, the grating was flickering. Is it a phenomenon of open soldering? Not right! I soldered this chip? At present, this welding level welding is absolutely no problem? (This is not bragging, really!) I still have confidence in myself, so I continue to touch, (*^__^*) Hey..., touched and touched, the screen suddenly lit up, hehe! Touched it? Touched and touched, and finally found that touched the crystal, as long as the hand touched the crystal screen is particularly bright, is it haunted? In order to verify the results, shut down, power on, then shut down, and then turn on the machine, the machine can not be opened at this time, immediately touch the crystal oscillator, the screen is bright again, so it is determined that the second is not turned on is definitely caused by the crystal, and quickly take it Next, look at the crystal above the display is H14.31818MF, this number has never seen it? How can I find this thing? It is also awkward to find the fault. (The maintenance personnel are afraid of this.) I decided to rummaging and looking for it. Not to mention, I found it on a board that I didn’t know. I quickly replaced it and repeatedly turned on the fault. I haven’t been there. At this point, the TV that has been plagued for many days has finally been solved by me. It seems that everything can be solved without perseverance and perseverance. The first time I hit so many words in one breath, my hands were a bit sour, but I can provide you with some maintenance experience. This is what I am most willing to do. Thank you for watching!

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