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Model No: CT-21FDS1
Version 1.0
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 TDA93XX circuit, the clock pulse is generated by pin58 / pin59 of N301 and 12M crystal oscillator.
Television’ s remote-control system also needs reset circuit that can preset the values in internal register. The circuit around pin57 of N204 is called auto-reset circuit. If UOC detects errors in resetting, it will come to the state of
programme protected.
The detail checking and repairing steps are as follow:
4.98V
4.98V
=3.6V
4.98V
YES
=5V
NO
5V
5V
D901 does not work
The voltage on the pin 42 of D901
Observe if there is sine wave on the pin 31 or pin
32 of D901 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 Z900, D901
Check R939,VD922
Check the voltage on the pin 33 of D901
Check T501, VD553,R558
Check D901
Check the voltage on the emitter of V925
Check the voltage on the positive pole of VD921
Check VD921, R933
Check R932,R937,V925
Check R937
