Panasonic OmniVision PV-M1326, Service Manual, Page: 5 / 173

1-3
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
25.0KV : Model
A,B,C,D,E,F,G or 30.0KV : Model H,I,J,K or
32.0KV : Model L
(see chart, Page 1-1) 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
23.5±1.5KV : Model A,B,C,D,E,F,G or
28.5±1.5KV : Model
H,I,J,K
or
30.0±2.0KV : Model L
(see chart, Page 1-1).
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.
HORIZONTAL OSCILLATOR DISABLE CIRCUIT TEST
SERVICE WARNING :
The test must be made as a final check before set is returned to the customer.
1. With the rear cover removed, supply about a 120V AC power source to the set, turn on the set.
2. Set the customer controls to normal operating positions.
3. Short between TP91 and TP92 on the Main circuit board with a jumper wire. Confirm that the picture goes out of horizontal sync.
4. If this does not occur, the horizontal oscillator disable circuit is not operating. Follow the Repair Procedures of horizontal oscillator
disable circuit before the set is returned to customer.
REPAIR PROCEDURES OF HORIZONTAL OSCILLATOR DISABLE CIRCUIT
1. Connect a DC voltmeter between capacitor C555 (+) on the Main circuit board and chassis ground.
2. If approxi21.9V is not present at that point when 120V AC is applied, find the cause. Check R515, R5505, R5507, C555
and D554.
3. Carefully check above specified parts and related circuits and parts. When the circuit is repaired, try the horizontal oscillator disable
circuit test again.
CIRCUIT EXPLANATION
HORIZONTAL OSCILLATOR DISABLE CIRCUIT
The positive DC voltage, supplied from the D554 cathode for
monitoring high voltage, is applied to the IC5301 Pin11 through
R515 and R5504. Under normal conditions, the voltage at
IC5301 Pin11 is less than approx 3V. If the high voltage at
Flyback Tr Pin 5 exceeds the specified voltage, the positive
DC voltage which is supplied from the D554 cathode also
increases. The increased voltage is applied to IC5301 Pin11
through R515 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 becomes dark in order to keep X-
radiation under specification.
Figure 2
IC5301
11
+
-
+
-
R5505
R515
D554
C555
C5507
To Pin 5
of Flayback
Transformer
R5504
R516
(Model : L)