Early this morning, a user sent a 25-inch Changhong (G25D19). From his description, the indicator light is on but not turned on. The cover is measured and the standby voltage is 65V. 115V (the machine + B voltage is 115V), measuring the acceleration pole and the filament have no voltage, it proves that the line is not working, is getting ready to check the phone when receiving a user, saying that there are two air conditioners need to be repaired, hang up the phone The TV user left a contact number and waited for the notice. He emphasized that if he exceeded 120 yuan, he would give up treatment, okay! Hey, can't be too much fat, wait until the afternoon is free to study....... After eating a nap, I woke up and nearly 2 o'clock. After sitting for a while, I began to capture the Changhong. I observed it carefully. R877 (470 ohms) on the power board, a crack measurement has been opened with two 1K parallel replacement. There is still no response after turning on the board. When the board is turned over during standby, the line pushes the C pole voltage to 28V B pole 0.45V. B turned out to be the negative pressure after the second boot, the tube C pole actually only 3V B pole up to 0.75V obviously driving the tube is saturated, measuring the TB1238AN 28 feet of the line oscillation power supply is as high as 26V and standby 9.3V is really amazing Blame, a blueprint on the Internet, know that the 9-pin 9V power supply is obtained by the power supply part of the N861 (LM317), the voltage is controlled by the CPU, in the standby time, the N861 input pin is 9.8V control pin is 7.5 The V output pin is 9.3V. After the power is turned on, the input pin is 26.8V. The control pin is 24.5V. The output pin is 26V. Checking the peripheral components of the N861 has no problem. It is considered that the N861 is not ideal. In fact, it is not ideal. Repair the electric car next door. Dismantled on the waste controller The LM317 is still replaced by a sound. After sucking a cigarette, the output of the hanging N861 is measured at 1.4V during standby. 9V is turned on. The load on the N861 is 9.3V. The standby is 26V. Is the 9V load? Is there a short circuit between the upper component and the components on the other power supply group? Looking at the drawing again, I found that the 9V is connected to the 18-pin of the CPU through D803 (2CK750) and 27V (with sound supply). It is also connected to the 18-pin of the CPU through D801 (2SK750) (this pin is the overcurrent protection detection input pin). Are these two diodes broken down? Finding the D803 and D801 measurements has actually broken down, recalling the broken R877, may be the cause of damage to the two diodes, both diodes are replaced with IN4148, when measuring the output of the N861 is 1.4V standby 9V measurement pushes the tube C to 65V when it is in standby. 115V after booting. Pushing the tube B to start up at 0V. It seems that TB1238 has been gloriously sacrificed. Remove one on the old board and replace the long-lost high-voltage sound. Also immediately lit up, connected to the letter sound good, OK! Changhong G25D19B.pdf
In fact, what people usually call a pinhole camera does not use a pinhole lens. Pinhole lens refers to a lens that uses the principle of small hole imaging to obtain images. It is inexpensive and simple in principle, but its fatal weakness is that too little light passes through the small hole, resulting in too long exposure time. Taking photos with a pinhole lens in sunlight can take anywhere from a few minutes to a dozen minutes, especially when shooting at night with exposure times of up to several hours. Obviously, for a camera that shoots dozens to dozens of frames per second, it cannot meet the requirements. Pinhole lenses cannot be applied to cameras, so there is no "pinhole" camera in the strict sense. As is customary, a miniature camera using a fisheye lens, a flat lens or a conical lens is called a pinhole camera.
According to the lens, the lens of the pinhole camera can be divided into three types: fisheye lens, flat lens and conical lens; according to the photosensitive element used, it can be divided into charge coupled element and complementary metal oxide semiconductor; According to the data transmission method, it can be divided into two categories: wireless cameras and wired cameras.
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