The first overhaul the camera power supply of all stripes are normal. Then use the oscilloscope test B30112 feet, measured the Vp - 1.5 point p signal waveform. From this part explained the CCD signal is basically normal. B302 and test of (1), (2), (3) feet without normal signal output. Shows faults in the digital video circuit. According to the digital circuit described earlier repair three principles: first of all on test (VEP23146B) unit plate B302 end pet-name ruby, AD5V, attending the feet, 11 feet cAM9V, 20 feet CAM15V, CAM - 8 v 21 feet. 22, 23 feet CAM3.5 V, conform to the requirements. Instructions sent by the camera power supply circuit of the power supply voltage is correct. So the next step should be to test the chip pin voltage is correct. When the test IC307 (MN655431SH) A/D conversion chip (1) the foot DE, found without the correct power supply voltage of 3.5 V. As there is no normal working voltage IC307 (1) the feet. Is likely to make A/D conversion circuit does not work, and make the whole process of video signal in digital circuits can not correctly. In digital circuit, the chip's power supply side most string have anti interference protection inductance. The inductance of the main role is to prevent the power supply ripple component in the digital circuit of wrong action. Through inspection of 3.5 V power supply is L307 (6.8 mH) from inductance. QPpservice manual download site
 QPpservice manual download site
Then test on both ends of the inductance of ground potential, found a 3.5 V voltage at one end, end without a 3.5 V voltage. Accidentally touch the inductance, suddenly discovered that images appear in the viewfinder, judged the inductance open at one end. With electric welding on both ends of inductive heating, but after welding to boot in the viewfinder image and no. Shutdown with test table L307 hall, whose hands did not move, show L307 inductance itself internal poor contact. After replacing L307 boot display image is normal, recording and playback, image.QPpservice manual download site