26SL41M, 26SL71M
29SL81M
IMPORTANT SERVICE SAFETY PRECAUTION
Service work should be performed only by qualified service technicians who are throughly
familiar with all safety checks and the servicing guidelines which follow:
WARNINGX-RADIATION AND HIGH VOLTAGE LIMITS
1. For continued safety, no modification of any circuit1. Be sure all service personnel are aware of the
should be attempted.procedures and instructions covering X-radiation. The
2. Disconnect AC power before servicing.only potential source of X-ray in current solid state
3. Semiconductor heat sinks are potential shockTV receivers is the picture tube. However, the picture
hazards when the chassis is operating.tube does not emit measurable X-Ray radiation, if
4. The chassis in this receiver has two ground systemsthe high voltage is as specified in the "High Voltage
which are separated by insulating material. The non-Check" instructions.
isolated (hot) ground system is for the B+ voltageIt is only when high voltage is excessive that X-
regulator circuit and the horizontal output circuit. radiation is capable of penetrating the shell of theThe
isolated ground system is for the low B+ DC voltagespicture tube including the lead in the glass material.
and the secondary circuit of the high voltageThe important precaution is to keep the high voltage
transformer.below the maximum level specified.
To prevent electrical shock use an isolation2. It is essential that servicemen have available at all
transformer between the line cord and powertimes an accurate high voltage meter.
receptacle, when servicing this chassis.The calibration of this meter should be checked
periodically.
3. High voltage should always be kept at the rated value
SERVICING OF HIGH VOLTAGE SYSTEM-no higher. Operation at higher voltages may cause
a failure of the picture tube or high voltage circuitry
AND PICTURE TUBE
and;also, under certain conditions, may produce
When servicing the high voltage system,radiation in exceeding of desirable levels.
remove the static charge by connecting a4.When the high voltage regulator is operating properly
there is no possibility of an X-radiation problem. Every
10k ohm resistor in series with an insulated
time a color chassis is serviced, the brightness should
wire (such as a test probe) between the pic-
be tested while monitoring the high voltage with a
ture tube ground and the anode lead. (ACmeter to be certain that the high voltage does not
line cord should be disconnected from ACexceed the specified value and that it is regulating
outlet.)correctly.
5. Do not use a picture tube other than that specified or
1. Picture tube in this receiver employs integral
make unrecommended circuit modifications to the
implosion protection.
high voltage circuitry.
2. Replace with tube of the same type number for
6. When trouble shooting and taking test measurements
continued safety.
on a receiver with excessive high voltage, avoid being
3. Do not lift picture tube by the neck.
unnecessarily close to the receiver.
4. Handle the picture tube only when wearing
Do not operate the receiver longer than is necessary
shatterproof goggles and after discharging the high
to locate the cause of excessive voltage.
voltage anode completely.
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ACEC
SHARP
