Panasonic CT-27C8G Service Manual page 3

Unplug the A.C. cord and connect a jumper between the two plug prongs.Measure the resistance
between the jumpered AC plug and expose metallic parts such as screwheads, antenna
terminals, control shafts, etc. If the exposed metallic part has a returnpath to the chassis, the
reading should be between 240k and 5.2M . If the exposed metallic part does not have a
return path to the chassis, the reading should be infinite.
Leakage current hot check
Plug the AC cord directly into the AC outlet. Do not use an isolation transformer during the check.
Connect a 1.5k 10 watt resistor in parallel with a 0.15 F capacitor between an exposed
metallic part and ground. Use earth ground, for example a water pipe.
Using a DVM with a 1000 ohms/volt sensitivity or higher, measure the AC potential across the
resistor.
Repeat the procedure and measure the voltage present with all other exposed metallic parts.
Verify that any potential does not exceed 0.75 volt RMS. A leakage current tester (such a
Simpson model 229, Sencore model PR57 or equivalent) may be used in the above procedure, in
which case any current measure must not exceed 0.5 milliamp. Ifany measurement is out of the
specified limits, there is a possibility of a shock hazard and the receiver must be repaired and
rechecked before it is returned to the customer.
Hot check circuit
Insulation test
Connect an insulation tester between an exposed metallic part and A.C. line. Apply 1080VAC/
60Hz for 1 second. Confirm that the current measurement is 0.5mA ~ 2.0mA. Repeat test with
other metallic exposed parts.
X ray radiation
WARNING
The potential source of x ray radiation in the TV set is in the high voltage section and the picture
tube.
NOTE
It is important to use an accurate, calibrated high voltage meter.
Set the brightness, picture, sharpness and color controls to minimum.
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