akira CT-21LPS1MKI/ANZ, Руководство по обслуживанию

Страница: 13 / 74

13
Model No: CT-21LP S 1MKI-ANZ
Version 1.0
4. Only vertical line in the middle of the screen
This is a dangerous failure. It probable causes flashover and smoking inside the set. Don’t let your TV work for a long time as this failure appears. Because the electron beam can not move in the horizontal orientation, the
failure should be in the horizontal deflection circuit. We mainly check the open-circuit fault in horizontal deflection circuit. The detail checking and repairing steps are as follow:
5. UOC does not work
In television, remote-control system is similar with the computer system. In theory, it can work if it holds two conditions as follow:
The power supply: In general, it is 5V, the error is not above 10% and the disturbance pulse is as small as possible.
The clock pulse: In
TMPA88XX circuit, the clock pulse is generated by pin 6 / pin 7 of N204 and 12M crystal oscillator.
Television’s remote-control system also needs reset circuit that can preset the values in internal register. The circuit around pin 5 of N204 is called auto-reset circuit. If UOC detects errors in resetting, it will come to the state of
program protected.
The detail checking and repairing steps are as follow:
YES
YES
NO
Vertical line
Repair CRT The horizontal yoke is opened or not
Whether “ XZ411” is opened
Check if there is bad solder between XZ411, and the main board
Check L414, C412, C415, C416 especial in inductive components and connector
NO
4.98V
＜
4.98V
=3.6V
＜
4.98V
YES
=5V
NO
＜
5V 5V
N204 does not work
The voltage on the pin 9, pin44,
pin55 of N204
Observe if there is sine wave on the pin 6 or pin 7
of N204 with an oscilloscope
Check the voltage on the positive pole of L901
NO
YES
4.98V
4.98V
Check alternant voltage on secondary coil of T501,
Check Z901, N204
Check R939,VD922
Check the voltage on the pin 5 of N204
Check T501, VD553, R558
Check N204 Check the voltage on the emitter of V902
Check the voltage on the positive pole of VD902
Check VD902, R947
Check R949, R945,V902
Check R945