12V power adapter, pull the plug into the might socket, no sparks, indicating that the primary circuit has failed. Open the power add shell, the ability provide works well .
cautiously observe the components, there are no burn marks, and there are no signs of overheating and yellowing on the back of the lap board. Use a multimeter to measure the baron input terminal, period eternity, the arrow does not respond .
Pay attention to check the current-limiting resistor, fuse and rectifier diode. It is found that the fuse is blown, and it is judged that there may be a short-circuit fault in the tour. Online measurement of the rectifier filter capacitor, there is no charging response, no response to the test of the meter pen, and the pointer indicates the resistor is about 100k .
The percolate capacitor is welded and measured with a multimeter in 1K mode. There is no charging reaction. The resistance measure is 30k. Reverse measurement. It is inactive a 30k resistance and there is no charging reaction. Carefully observe that there is a trace of escape on the capacitor ’ s negative electrode. then re-measure the input might input terminal, the resistance is about 1 megohm, the input underground is convention .
indicates that the office failure should be caused by the breakdown and escape of the percolate capacitor. Because there is no 400v10u filter capacitor on hand, and there is placid a place for a filter capacitor on the racing circuit board, two capacitors 400v3.9u and 400v6.8u are used in parallel to connect to the tour. Solder the fuse, measure the remark end of the power provide at the 1K crop of the multimeter, and the underground is 1 MΩ, indicating that the circuit has returned to normal .
measuring stick the output diode of the secondary power provision, and there is no sign of price. power on, the indicator light is on. No-load measurement output voltage, 13v, in the normal range. Connect the 20Ω slickness electrify rheostat into the circuit, adjust the resistance, keep the current at 2A, and power on for 30 minutes without any failure. Put the circuit display panel into the blast, continue to power on for 30 minutes, the blast is affectionate .
Because the adapter is used for monitoring equipment, 24 hours adam 365 days use, it is estimated that the exponent adapter has been working for a long fourth dimension because of poor heat profligacy of the might supply and the capacitor overheats and leaks. For policy, 30 small holes were drilled with a 1MM exercise sting on the side of the low-tension region of the adapter shell to facilitate inflame waste. At this point, the repair is dispatch .