Last night, I was chatting with Q friends in Tiannanhaibei. The apprentice called and shouted "I am mad!" Please ask me to clean up the mess. Notonthehighstree Notonthehighstree33 Bossgoo(China)Tecgnology.(Bossgoo(China)Tecgnology) , https://www.cn-gangdao.com
Model: Changhong CHD29300
Fault: The following picture looks like an easy fault. Turn on the full screen green retrace line, you can see the faint silhouette. After playing for about 40 minutes, the image is normal.
Apprentice overhaul process:
I believe that the first reaction of 100% of the maintenance personnel is: the discharge capacitor has gone!
If it is such a judgment, then the old guy show tells you - wrong bird!
The apprentice also thought that the capacitor was bad. However, the detection voltage, 200V is normal. Remove the 33UF/250V capacitor detection, and there is no problem with charging and discharging.
The apprentice lowered the accelerating voltage and the image was normal! Installed, tested, and the fault reappears! Then turn down the accelerating voltage and the image is normal again! I thought that the high voltage package was broken, and I rushed to buy it, and the test machine was normal. However, when the shell is replaced in the test machine, the TV is still "mountain is still the mountain, the beam is still the beam"! I thought it was a virtual welding, a large area of ​​repair welding, can not be changed, tossed for more than 2 hours, no choice, no choice but to call for help.
Nothing to consider, the high voltage package has been replaced, the voltage is normal, and the back cover is not replaced. Oh, it seems to be a bit of a challenge, but the old guy I like the most is the challenge of intractable diseases.
Turn on the board, shake the board, and the image is normal. No matter how you hit the circuit board, the TV always smiles. This guy, are you kidding? The failure does not occur, can not check the relevant data, how to start?
Lenovo associates that the image is 40 minutes after the boot is normal, decisively called the apprentice stop! Ignore it, drink tea and chat about the world.
Unconsciously, more than an hour passed, boot! The long-lost fault finally appeared! Check the green gun voltage. When the test leads touch the tailgate, the user exclaimed: "Okay!" This time, I proved that my judgment is 100% accurate. Handcing the tailgate with your hand, the fault is again, oh! Order the apprentice to replace the socket and repair the tail plate.
The test machine is installed, normal, leaving people to drink!
Tips: Because the working current of the high-definition machine is much larger than that of the ordinary CRT, and the weight of the tailstock is large, the quality of the currently available socket is not flattering (the machine has changed the socket). Therefore, over time, due to the long-term energization work of the socket pin, it is very normal to have a wrong connection between the pin and the socket pin. The high-definition machine has a great influence on the image due to the internal speciality. If it is a common image tube, the same is true for the poor contact of the tube holder, but the HD tube is not the case, but the image change fools people! Why the machine is unpacked and normal is not normal. It is estimated that the circuit board is pulled out when the device is unpacked, and the connection of the tail plate is relatively tight so that the socket pins are in good contact. This example of the fault is no stranger, because the experience is accumulated. I hope that the dedication of the old guy will help you in the future! Thanks for reading!