The machine starts on the left side of the screen had a 2 cm and 1 cm wide black stripes, and on the left side of the screen edge burr, still can hear machines "hiss" noise, grating is dim, later on the left side of the black bar slowly disappear, but after shutdown boot failure will appear again. 7Ppservice manual download site
 7Ppservice manual download site
This machine seems to think the serious illness, is a little hard to lay their hands on, based on the principle of multiple fault to solve them one by one, first time question. For device will disappear with time, considering that should be a capacitor leakage or let instability, and may be related to the power supply line and output capacitor, and since the wave of the secondary power supply capacitor failure rate is higher, so decided to replacement it. When using a capacitance substitution specification is the original, after the second wave power Huan capacitance boot Mafia disappeared immediately, on the left side of the burr was gone, "hissing" sound. 7Ppservice manual download site
 7Ppservice manual download site
 7Ppservice manual download site
Now machine is the phenomenon of dark, narrow line of grating, this phenomenon can be concluded that for the secondary power supply (parallel booster type) did not start. Display the power did not start can be divided into two situations: one is the secondary power supply itself has a problem, for example: the secondary power field effect tube failure, there is something wrong with the PWM signal path, etc.; Another case is the secondary power supply voltage feedback channel is out of order, cause line field scan chip as the secondary power supply high voltage output and reduce the output voltage or vibration. 7Ppservice manual download site
 7Ppservice manual download site
Specific to the machine related circuit as shown in figure. Look carefully the machine found a second power supply voltage feedback circuit resistance R two feet with marks of overheating, flipped the circuit board, the resistance R is burned into gray, and the series of capacitance C has breakdown, the two component replacement after electrify of commissioning, clearly heard good (secondary power don't start without obvious) high pressure: the launch of sound, but disappeared immediately. Check the X-ray protection IC, when using a multimeter red table pen to IC (25), display immediately start to normal. Now found grating brighter in predicament, so little G2 to grating is normal. Everything is ok after shutdown to boot.

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