2 X-RADIATION
WARNING :
1. The potential source of X-Radiation in TV sets is the High
Voltage section and the picture tube.
2. When using a picture tube test fixture for service, ensure
that the fixture is capable of handling 33.0 kV without
causing X-Radiation.
NOTE:
It is important to use an accurate periodically calibrated high
voltage meter.
1. Reduce the brightness to minimum.
2. Set the SERVICE switch to SERVICE.
3. Measure the High Voltage. The meter reading should
indicate 28.0 kV±1.5 kV.
If the meter indication is out of tolerance, immediate service
and correction is required to prevent the possibility of
premature component failure.
4. To prevent an X-Radiation possibly, it is essential to use the
specified picture tube.
2.1. HORIZONTAL OSCILLATOR
DISABLE CIRCUIT TEST
SERVICE WARNING :
The test must be made as a final check before set is returned
to the customer.
CONFIRMATION OF X-RAY MOVEMENT
1. Turn off TV set.
2. Connect the circuit below between TP554 and TP553 on
the Deflection C.B.A.
Figure 2
3. Turn on SW1 and then turn on the set. Confirm that the
picture is on the screen properly.
4. Confirm that the picture goes out of horizontal sync while
getting down by varying VR.
5. If this does not occur, it means that X-ray protect circuit is
not operating. Further confirmation and repair is required.
2.2. REPAIR PROCEDURES OF
HORIZONTAL OSCILLATOR
DISABLE CIRCUIT
1. Connect a DC voltmeter between capacitor C513 (+) on the
Main circuit board and chassis ground.
2. If approxi21.5 V (For model with 20 inch CRT),
+20.0 V (For model with 27 inch CRT) is not present at that
point when 120 V AC is applied, find the cause. Check
R508, R503, R5504, R5505, D503, C513 and C5507.
3. Carefully check above specified parts and related circuits
and parts. When the circuit is repaired, try the horizontal
oscillator disable circuit test again.
2.3. CIRCUIT EXPLANATION
2.3.1. HORIZONTAL OSCILLATOR
DISABLE CIRCUIT
The positive DC voltage, supplied from the D503 cathode for
monitoring high voltage, is applied to the IC5301 Pin11 through
R508, R503 and R5504. Under normal conditions, the voltage
at IC5301 Pin 11 is less than approx. 6 V. If the high voltage at
Flyback Transformer Pin 5 exceeds the specified voltage, the
positive DC voltage which is supplied from the D503 cathode
also increases. The increased voltage is applied to IC5301
Pin11 through R508, R503 and R5504. Due to the increased
voltage at IC5301 Pin11, the horizontal oscillator frequency
increases, the picture goes out of horizontal sync, the beam
current decreases and the picture become dark in order to
keep X-radiation under specification.
Figure 3
4
AG-520VDH
Summary of Contents for AG520VDH - COMB. DVD/VCR/TV
Page 7: ...4 ABOUT LEAD FREE SOLDER PbF 7 AG 520VDH ...
Page 9: ...Fig 1 6 9 AG 520VDH ...
Page 16: ...5 1 14 WIRE AND LEAD POSITION DIAGRAM Fig 12 16 AG 520VDH ...
Page 18: ...5 2 MAINTENANCE CHART 18 AG 520VDH ...
Page 20: ...Fig D2 20 AG 520VDH ...
Page 21: ...Fig D3 21 AG 520VDH ...
Page 22: ...Fig D4 22 AG 520VDH ...
Page 35: ...7 4 TEST POINTS AND CONTROL LOCATION 35 AG 520VDH ...
Page 36: ...36 AG 520VDH ...
Page 60: ...AG 520VDH 60 ...
Page 78: ...AG 520VDH 78 ...
Page 79: ...11 EXPLODED VIEWS 11 1 MECHANISM SECTION AG 520VDH 79 ...
Page 80: ...11 2 DVD SECTION AG 520VDH 80 ...
Page 81: ...11 3 CHASSIS FRAME SECTION 1 AG 520VDH 81 ...
Page 82: ...11 4 CHASSIS FRAME SECTION 2 AG 520VDH 82 ...
Page 83: ...11 5 CHASSIS FRAME SECTION 3 AG 520VDH 83 ...
Page 84: ...11 6 PACKING PARTS AND ACCESORIES SECTION AG 520VDH 84 ...
