Sharp 55R-WP4H, Service Manual

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22
61R-WP5H
55R-WP5H
Servicing precautions
1. Protector Operation
This model is provided with five protector circuits. Below discussed are the behaviors and indications of these circuits.
(Note: In some cases, the LED flashing cycle and possible trouble spot may be inconsistent.)
1
Over-current Protector Circuit:
A rush current into the flyback transformer is detected. The circuit is activated if an over-current flows in.
Indication: The power LED (red) flashes once.
2
X-Radiation Protector Circuit:
This circuit is activated if the rectified heater voltage rises above its specified level.
Indication: The power LED (red) flashes once.
3
Vertical Output Protector Circuit:
The vertical output is detected. The circuit is activated if the vertical output is missing (horizontal-only
screen or the like).
Indication: The power LED (red) flashes twice
4
+B Under-voltage Protector Circuit:
The voltages at the 10V, 25V, 32V, -8V and -25V lines of the switching regulator are detected. The circuit
is activated if any of the voltages drops below its specified level.
5
+B Over-voltage Protector Circuit:
The voltages at the 10V, 25V, 32V and -25V lines are detected. The circuit is activated if any of the
voltages rises above its specified level.
Indication: The power LED (red) flashes three times.
2. Stop of Protector Operation
The protector may be kept inactive by opening the detection circuits or grounding C3230 and C3231 (on the Signal
Unit). The vertical output protector circuit, however, cannot be made inactive.
Note: Be sure to get the protector back to normal after servicing.
6
IC507 (DEF PROCESSOR) I 2 C Bass ERROR Protector:
If for any reason, the IC507 fails to return an ACKNOWLEDGE signal to the microprocessor.
OFF
ON
0.2
(seconds)
1.4
0.2
ON
OFF
0.2 0.2
1.4
0.2
0.2 0.2
0.2
(seconds)
(seconds)
0.2 0.2 0.2
1.4
0.2 0.2
0.2 0.2 0.2
0.2 0.2
OFF
ON
(seconds)
0.2 0.2 0.2 0.4 0.4
OFF
ON