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11
Purpose
To prevent smoke, fire and the radiation of X-rays due to
abnormally high voltages by using detection circuits (listed
below) to instantly turn off the power in the event of a
problem. Also, depending on the circuit, the projection
tubes can be damaged in the event of a problem; therefore,
there is also a circuit that informs the blanking circuit when a
problem arises so that the video signals to the cathodes can
be blanked.
There is a circuit that prevents the power being turned on by
remote control once a problem is detected as follows;
Protection Circuit
1) Convergence –22V short-circuit (LED blink one time)
2) Convergence +22V short circuit (LED blink one time)
3) Convergence –12V short-circuit (LED blink one time)
4) Convergence +12V short circuit (LED blink one time)
5) Convergence +12V short circuit (LED blink one time)
6) Convergence +22V over current (LED blink one time)
7) Convergence –22V over current (LED blink one time)
8) Convergence –22V short-circuit (LED blink one time)
9) X-ray (LED blink two times)
10) Extra High Tension (EHT) (LED blink two times)
11) V-stop (LED blink three times)
12) +210V short circuit (LED blink two times)
13) +140v over current (LED blink two times)
14) +23V short circuit (LED blink two times)
15) +15V short circuit (LED blink two times)
16) +8V short circuit (LED blink two times)
17) +8(H)V short circuit (LED blink two times)
18) -15V short circuit (LED blink two times)
Operation.
Protection line of each circuit is connected to IC1101 pin 7.
When some of these pins go to “H”, this abnormal
information is informed to IC1101 (MPU) .
Then RELAY output pin No.27 of IC1101 voltage to “H”,
Q1030 turns ON, Q6751 base voltage drops to LOW and
trips the power supply relay RL6701. In such cases, the
main unit power lamps blinks to indicate that a protection
circuit is operating. (refer to LED blink time)
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