TH-98LQ70U, TH-98LQ70W, TH-98LQ70C - Panasonic TV Service Manual (repair manual). Page 2

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The service technician is required to read and follow the “Safety Precautions” and “Important Safety Notice” in this service manual.

1   When servicing, observe the original lead dress. If a short circuit is found, replace all parts, which have been 

 over-heated or damaged by the short circuit.

2 After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields

 are properly installed.

3 After servicing, make the following leakage current checks to prevent the customer from being exposed to

 shock hazards.

1 Unplug the AC cord and connect a jumper between the two prongs on the plug.
2 Measure the resistance value, with an ohm meter, between the jumpered AC plug and each exposed metallic

cabinet part on the equipment such as screwheads, connectors, control shafts, etc. The resistance value must
be more than 5MΩ.

Figure1

1 Plug the AC cord directly into the AC outlet.

 Do not use an isolation transformer for this check.

2 Connect a 1.5KΩ, 10W resistor, in parallel with a 0.15μ F capacitor, between each exposed metallic part on the

set an a good earth ground such as a water pipe, as shown in Figure1.

3 Use an AC voltmeter, with 1000 ohms/volt or more sensitivity, to measure the potential across the resistor.
4 Check each exposed metallic part, and measure the voltage at each point.
5 Reverse the AC plug in the AC outlet repeat each of the above measurements.

6 The potential at any point should not exceed 0.15 volts RMS. A leakage current tester 

(Simpson Model 229 equivalent) may be used to make the hot checks, leakage current must not exceed 0.1 milliamp. 
In case a measurement is outside of the limits specified, there is a possibility of a shock hazard, and the equipment 
should be repaired and rechecked before it is returned to the customer.

PCBs (manufactured) using lead free solder will have a PbF stamp on the PCB.
1 Pb free solder has a higher melting point than standard solder; Typically the melting point is 50–70℉ (30-40℃) higher.

Please use a high temperature soldering iron. In case of the soldering iron with temperature control, please set it to 
700±20℉ (370±10℃).

2 Pb free solder will tend to splash when heated too high (about 1100℉ /600℃ ).

  This service information is designed for experienced repair technicians only and is not designed for use by the general public.

  It dose not contain warnings or cautions to advise non-technical individuals of potential dangers in attempting to service a product.

  Products powered by electricity should be serviced or repaired only by experienced professional technicians. Any attempt to service

  or repair the product or products dealt with in this service information by anyone else could result in serious injury or death.