Changhong PF25118 color TV repeated data error reasons and countermeasures Changhong PF25118 color TV, there is often a data error (accurately said data initialization) failure. The fault phenomenon is: after the normal shutdown, the next time the power is turned on, there is no picture, no noise, no noise, the channel number turns red, there is image after the automatic search, the sound is adjusted to 1 and the sound is as loud as 100, the field becomes larger, OK The frame is reduced by about 1cm and the pincushion is distorted. Every time it is processed, enter the bus, change OP1 from 3E to F0, OP4 from 5F to DF, then turn off the TV after the remote control, then the TV is normal, but every other day or two days The same failure occurred again. This is a flaw in the design of this machine! ! ! ! The root cause is that the line change does not match the flat picture tube, that is, the high voltage static electricity generated at the moment of opening or shutting down, the key board is sensed, and the CPU and the memory are input to initialize the CPU. As long as you carefully observe it, you will find that the high-voltage static electricity generated by the machine at the moment of opening or shutting down is particularly noticeable. Moreover, CPU initialization (data error) occurs all at the moment of dry weather opening or shutdown, because the high voltage static electricity is the strongest at that time! Commutators For Household Machines Commutators For Household Machines,Commutator For Washing Machines Motor,Commutator For Air Conditioning Motors,Commutator For Water Purifier Motor ZHEJIANG JIAGU ELECTRIC APPLIANCES CO. LTD , https://www.chinajiagu.com
Changhong color TV PF25118 repeated data error common problem - android - Phones Developers
The solution:
1. Change the original line to a change with a high-voltage bleeder resistor (I don't know if the manufacturer designed it).
2. Prevent high voltage static electricity from being induced to the keypad. This is also the way our maintenance staff can do it.
Method 1, (provided by Li Tianhao) The ground wire of the button is connected to the ground line of the picture tube, then the button circuit board is coated with a layer of insulating varnish, and then the power switch is placed on the outer layer with a metal scraping root. Solder to the CRT ground.
Method 2 (provided by chst) Connect two diodes of data and clock to each of the two diodes (4148 is OK). The two pins are connected to the positive and negative poles of the two diodes, and then the two negative poles are connected to 5V, and the two positive poles are grounded. The purpose is to prevent pulse interference at startup. Ground the chrome part of the keyboard.
Method 3, (provided by Xu Xiaofeng) manufacturers have technical changes; first find the connection with the storage fast 5V to remove it, replace it with inductance, then add a capacitor in the past, and then apply the hot melt on the metal part of the button panel Just!
Method 4, (provided by laowu2007) The switch is wrapped in thin tin foil for one turn, grounded with a wire, and four 1N1448 diodes are used for the 5th and 6th legs of the memory block 24C16, the positive poles of the two are connected to 5V, and the negative pole is tapped to the two legs. The other two positive poles 5 and 6 are grounded and the negative pole is grounded.
Method 5, (not provided by the person who solves the problem) disconnects the 7 feet of the memory, and then automatically searches for the program, adjusts the color, contrast, brightness, etc., and then connects the 7 feet through a 6.8K resistor to the 5V. This will also bring some inconvenience to the user, such as cable TV to add new programs need to re-automatic search and can not remember new programs and so on.