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Amoi VCD machine type 768 machine boot without a blue screen, the screen does not light, head automatically move to the outer edge and noise fault diagnosis method

Time£º2014-01-25 09:10:51  Source£ºNetwork  Author£ºUnknown  Clicks£º1140
  

 The boot after the TV without the blue screen, the screen does not light, estimate the fault range: the supply voltage is not normal; CPU motherboard does not reset; no oscillation clock signal; CPU GMS97C52 or decompressed block CL680 damage. Open the cover to check, found the reason is moved to the outer edge of the sound head backward to the motor is still kept, resulting in the drive slip sounding. First use the multimeter to measure the power of independent board of the JPP9 + 5V, + 9V, + 3.3V voltage, found + 5V voltage is about 3.1V, + 3.3V supply voltage solution plate with low to about 2.1V, there was no hot phenomenon touch each integrated circuit by hand, try to unplug the JPP9 socket, disconnect the load again, measuring the + 5V voltage is still low, that is not too heavy a load caused by fault, should be on the power panel. + 5V, + 3.3V power supply circuit is shown in Figure 2, + 5V, + 3.3V output is provided for the same set of power, measured DP01 rectifier output QP01 (2SB1274) of the E voltage, C voltage is low, careful examination of QP01, QP02 and a filter capacitor, resistor divider without exception, doubt CP08 SMD capacitors bad, tried to remove the boot, + 5V, + 3.3V voltage is normal, the plug connection is good after the test machine, everything is normal, with a grade of 104 ceramic capacitor welding in the CP08 position, repair the end.6UHservice manual download site