A Konka T21SA120 automatically turns off the red light, and the signal of the set-top box can be stuck for about one minute. Once the set-top box is plugged in immediately, press P+ to turn it on again. You must turn the power off again to turn it on again. When the machine is turned on, there is no obvious abnormality in the machine's line width, and the size and brightness of the grating are stable. Since there is no such maintenance experience, the first thing to think about is the desoldering. After the disassemble is repaired, the power-on fault remains. The measured +B voltage is stable at 110V, and the output of each channel is also very stable. The board is very clean and beautiful. It is suspected that the keypad is leaking, and the buttons are all replaced and the fault is not eliminated. In a forum, I saw this troubleshooting phenomenon and decided to protect the shutdown. Measure the base voltage of V906 (C1815). After starting up, it will slowly rise to 0.7V and the machine will shut down. According to the idea, the protection circuit is activated. Measure the voltage across the voltage regulator VD915 (6.2V), and slowly rise to 6.2V from the start-up time, the machine will stand by, and the negative voltage of the VD915 will be rectified by the row-changing filament pin, thus determining the line output overvoltage. MCU protection standby. The line output key suspect is the reverse-pass capacitor, and the reverse-capacitance (6800pF) is removed, measuring only 4.28nF, and the capacity is reduced by one-third. Ok, it must be it. From the old board, a 6.8nF measurement is 6.64nF, the machine is normal, and it is no longer automatically shut down, so the machine is repaired.
The OEM pressure core with high performance and high stability is used as the signal measuring element. The sensor signal is converted into standard signal output after special signal processing. After long-term aging and stability screening, the product performance is stable and reliable. It is applied to the outdoor site with poor environment. At the same time, it can display the field pressure, and the zero point and full range can be moved.
Jb400 pressure transmitter installation interface form can not only be processed according to the user's requirements, but also provide specifications compatible with other brands of transmitters. This series of products are widely used in industrial process control, petroleum, chemical industry, metallurgy and other industries.
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