Panasonic TX-21JT2P specifications Contents

CONTENTS
SAFETY PRECAUTIONS	2
SERVICE HINTS	3
ALIGNMENT SETTINGS	4
WAVEFORM PATTERN TABLE	5
BLOCK DIAGRAMS	6
PARTS LOCATION	7
REPLACEMENT PARTS LIST	8
SCHEMATIC DIAGRAMS	12
CONDUCTOR VIEWS	17

SAFETY PRECAUTIONS

GENERAL GUIDE LINES

1.	It is advisable to insert an isolation transformer in the
	a.c. supply before servicing a hot chassis.
2.	When servicing, observe the original lead dress in the
	high voltage circuits. If a short circuit is found, replace
	all parts that have been overheated or damaged by
	the short circuit.
3.	After servicing, see that all the protective devices
	such as insulation barriers, insulation papers, shields
	and isolation R-C combinations are correctly
	installed.
4.	When the receiver is not being used for a long period
	of time, unplug the power cord from the a.c. outlet.
5.	Potentials as high as 30kV are present when this

4.Check each exposed metallic part and check the voltage at each point.

5.Reverse the a.c. plug at the outlet and repeat each of the above measurements.

6.The potential at any point should not exceed 1,4Vrms. In case a measurement is outside the limits specified, there is a possibility of a shock hazard, and the receiver should be repaired and rechecked before it is returned to the customer.

HOT CHECK CIRCUIT

receiver is in operation. Operation of the receiver

without the rear cover involves the danger of a shock

hazard from the receiver power supply. Servicing

should not be attempted by anyone who is not

familiar with the precautions necessary when working

on high voltage equipment. Always discharge the

anode of the tube.

6. After servicing make the following leakage current

checks to prevent the customer from being exposed

to shock hazard.

LEAKAGE CURRENT COLD CHECK

1. Unplug the a.c. cord and connect a jumper between

the two prongs of the plug.

a.c. VOLTMETER

2kΩ 10 Watts

TO INSTRUMENT'S EXPOSED

METALLIC PARTS Fig. 1.

WATER PIPE

(EARTH)

2. Turn on the receiver’s power switch.

3. Measure the resistance value with an ohmmeter,

between the jumpered a.c. plug and each exposed

metallic cabinet part on the receiver, such as screw

heads, aerials, connectors, control shafts etc. When

the exposed metallic part has a return path to the

chassis, the reading should be between 4M ohm and

20M ohm. When the exposed metal does not have a

return path to the chassis, the reading must be

infinite.

LEAKAGE CURRENT HOT CHECK

1.Plug the a.c. cord directly into the a.c. outlet. Do not use an isolation transformer for this check.

2.Connect a 2kΩ 10W resistor in series with an exposed metallic part on the receiver and an earth, such as a water pipe.

3.Use an a.c. voltmeter with high impedance to measure the potential across the resistor.

X-RADIATION WARNING

1.The potential sources of X-Radiation in TV sets are the high voltage section and the picture tube.

2.When using a picture tube test jig for service, ensure that the jig is capable of handling 30kV without causing X-Radiation.

NOTE: It is important to use an accurate periodically calibrated high voltage meter.

1.Set the brightness to minimum.

2.Measure the high voltage. The meter should indicate. 29kV ± 1kV.

If the meter indication is out of tolerance, immediate service and correction is required to prevent the possibility of premature component failure.

3.To prevent any X-Radiation possibility, it is essential to use the specified tube.

2