CHAPTER 1. IMPORTANT SERVICE SAFETY PRECAUTION
E Market Service 14T1-L Manual TV
 IMPORTANT SERVICE SAFETY PRECAUTION
IMPORTANT SERVICE SAFETY PRECAUTION
Service work should be performed only by qualified service technicians who are thoroughly familiar with all safety checks and the servicing guidelines which follow: WARNING
1. For continued safety, no modification of anycircuit should be attempted. 2. Disconnect AC power before servicing. 3. Semiconductor heat sinks are potential shock hazards when the chassis is operating. 4. The chassis in this receiver has two ground systems which are separated by insulating material. The nonisolated (hot) ground system is for the B+ voltage regulator circuit and the horizontal output circuit. The isolated ground system is forthe low B+ DC voltages and the secondary circuit of the high voltage transformer. To prevent electrical shock use an isolation transformer between the line cord and power receptacle, when servicing this chassis.
X-RADIATION AND HIGH VOLTAGE LIMITS
1. Be sure all service personnel are aware of the procedures and instructions covering X-radiation. The only potential source of X-ray in currentsolid state TV receivers is the picture tube. However, the picture tube does not emit measurable X-Ray radiation, if the high voltage is as specified in the "High Voltage Check" instructions. It is only when high voltage is excessive that Xradiation is capable of penetrating the shell of the picture tube including the lead in the glass material. The important precaution is to keep the high voltagebelow the maximum level specified. 2. It is essential that servicemen have available at all times an accurate high voltage meter. The calibration of this meter should be checked periodically. 3. High voltage should always be kept at the rated value −no higher. Operation at higher voltages may cause a failure of the picture tube or high voltage circuitry and;also, under certain conditions, mayproduce radiation in exceeding of desirable levels. 4. When the high voltage regulator is operating properly there is no possibility of an X-radiation problem. Every time a color chassis is serviced, the brightness should be tested while monitoring the high voltage with a meter to be certain that the high voltage does not exceed the specified value and that it is regulating correctly. 5. Do not use apicture tube other than that specified or make unrecommended circuit modifications to the high voltage circuitry. 6. W h e n t r o u b l e s h o o t i n g a n d t a k i n g t e s t measurements on a receiver with excessive high voltage, avoid being unnecessarily close to the receiver. Do not operate the receiver longer than is necessary to locate the cause of excessive voltage.
SERVICING OF HIGHVOLTAGE SYSTEM AND PICTURE TUBE When servicing the high voltage system, remove the static charge by connecting a 10k ohm resistor in series with an insulated wire (such as a test probe) between the picture tube ground and the anode lead. (AC line cord should be disconnected from AC outlet.)
1. Picture tube in this receiver employs integral implosion protection. 2. Replace with tube of the sametype number for continued safety. 3. Do not lift picture tube by the neck. 4. Handle the picture tube only when wearing shatterproof goggles and after discharging the high voltage anode completely.
IMPORTANT SERVICE SAFETY PRECAUTION
(Continued) BEFORE RETURNING THE RECEIVER (Fire & Shock Hazard)
Before returning the receiver to the user, perform the following safety checks.1. Inspect all lead dress to make certain that leads are not pinched or that hardware is not lodged between the chassis and other metal parts in the receiver. 2. Inspect all protective devices such as non-metallic control knobs, insulating materials, cabinet backs, adjustment and compartment covers or shields, isolation resistor-capacity networks, mechanical insulators, etc. 3. To be sure that no...