After the restoration of the original circuit , press the main power switch , first red light , green light later ( ie secondary boot ) , while CRT filament flashing , then goes out and the green light is still bright. With an oscilloscope V432, V431 c pole no wave , no figures point A power waveform , while N30l13 foot wave normal , and thus determine the X-ray protection circuit due. At this point detection N433 (BTl69) G -pole voltage of about 2.1V , and then measuring the voltage across VD432 were also approximately 2.2V, but check point B filament AC voltage 4. OV normal , and thus determine VD432 (18V regulator ) leakage or poor . Try to disconnect one end of the grating appeared , but the image seriously out of step the line frequency . Thus proving the initial cause of the failure of this machine is bad N30114 -pin external crystal G303, resulting in a change in the line -frequency switching pulse duty cycle , resulting in repeated loss of line pipe . Crystal replacement 503k (32 times the line frequency ) and then will VD432 ones , troubleshooting.vmGservice manual download site

    Summary: In the drawings , A is the point controlled by two factors : one is the standby CPU N00126 foot control, when remote shutdown , N00126 0V output pin low , V016 off , V017 conduction , A point of switching pulses signal is bypassed , the line output stage stops working , at the same time , N00126 foot control switch off power supply 12V output , so that the green light is off, the red light ; second is the x-ray protection circuit control, when the line current is too large or row negative peak pulse when the high reverse process , B -point pulse voltage increases , VD431 rectified output is increased, when the rectified output voltage exceeds 18V, VD432 breakdown conduction : SCR V433 also turns on, the switching pulse at point A be bypassed to ground through C465 , and B4 (24V) through R437, VD433 to be pulled down, thus pushing the line and line -level output stage to stop working, but this is still bright green . So , just grab these two features point A controlled and green reaction phenomenon , through proper maintenance of ideas, it is not difficult troubleshooting .

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