SAFETY INSTRUCTIONS
GENERAL GUIDELINES connectors, control shafts etc. When the
exposed metallic part a return path to the
1. It is advised to insert an isolation transformer chassis the reading should be between
in the AC supply before servicing a hot 4Mohm and the 20Mohm. When the
chassis. exposed metal does not have a return path
to the chassis, the reading must be infinite.
2. Potentials as high as 33KV are present when
this receiver is in operation. Operation of the LEAKAGE CURRENT HOT CHECK
receiver without the rear cover involves the
danger of a shock hazard from the receiver 1. Plug the AC cord directly in to the AC
power supply. Servicing should not be outlet. Do not use an isolation transformer
attempted by any one who is not for this check.
competent with the precautions necessary 2. Connect a 2Kohm 10W resistor in series with
when working on the high voltage an exposed metallic part on the receiver
equipment. Always discharge the anode of and an earth, such as a water pipe.
the tube. 3. Use an AC voltmeter with high impedance
to measure the potential across the resistor.
3. When servicing observe the original lead 4. Check each exposed metallic part and
dress in the high voltage circuits. If a short check the voltage at the each point.
circuit is found, replace all the parts which 5. Reverse the AC plug at the outlet and
have been overheated or damaged by the repeat each of the above measurements.
short circuit. 6. The potential at the any point should not
exceed 1.4 Vrms. In case a measurement is
4. Always use the manufacturer?s replacement outside the limits specified, there is the
safety components. The critical safety possibility of a shock hazard, and the
components marked with on the receiver should be repaired and rechecked
schematics diagrams should not be before it is returned to the customer.
replaced by other substitutes. Other
substitute may create the electrical shock,
fire or other hazards. Take attention to
replace the spacers with the originals. HOT CHECK CIRCUIT
Furthermore where a short circuit has AC-Voltmeter
occurred, replace those components that TO INSTRUMENTS
indicate evidence of overheating. EXPOSED
METALLIC PARTSWater pipe
(earth)
5. After servicing, see that all the protective
devices such as insulation barriers, insulation
papers, shields and isolation R-C 2 K Ohm
combinations are correctly installed.
6. When the receiver is not being used for a
long time of period of time, unplug the Figure 1
power cord from the AC outlet. X-RAY RADIATION WARNING
The primary source of X-ray radiation in this receiver
7. After servicing make the following leakage is the picture tube. The chassis is specially
current checks to prevent the customer
from being exposed to shock hazard. constructed to limit X-ray radiation. For continued
X-ray radiation protection, replace the tube with
LEAKAGE CURRENT COLD CHECK the same type of the original one.
CAUTION
1. Unplug the AC cord and connect a jumper
between the two prongs of the plug. AFTER REMOVAL OF THE ANODE CAP, DISCHARGE
THE ANODE OF THE PICTURE TUBE AND THE ANODE
2. Turn the receiver?s power switch on. CAP TO THE METAL CHASSIS, CRT SHIELD, OR THE
CARBON PAINTED ON THE CRT WITH A HIGH
VOLTAGE PROBE AND MULTIMETER (SELECT VDC)
3. Measure the resistance value with an
AND THEN SHORT CIRCUIT DIRECTLY TO DISCHARGE
ohmmeter, between the jumpered AC plug COMPLETELY.
and each exposed metallic cabinet part on
the receiver, such as screw heads, aerials, |
ACEC
