Sharp 13K-M150 Service Manual - Page 2

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13K-M100/150

CK13M10/15

IMPORTANT SERVICE SAFETY PRECAUTION

Service work should be performed only by qualified service technicians who are thoroughly familiar with

all safety checks and servicing guidelines which follow:

WARNING

1. For continued safety, no modification of any circuit

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 insulation material. The non-

isolated (hot) ground system is for the B+ voltage

regulator circuit and the horizontal output circuit.The

isolated ground system is for the 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.

CAUTION: FOR CONTINUED

PROTECTION AGAINST A

RISK OF FIRE, REPLACE

ONLY WITH SAME TYPE 4A-

4A 125V

125V FUSE.

SERVICING OF HIGH VOLTAGE SYSTEM

AND PICTURE TUBE

When servicing the high voltage system, re-

move 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 same type 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.

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 current solid 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 X-

radiation is capable of penetrating the shell of the

picture tube including the lead in glass material. The

important precaution is to keep the high voltage below

the maximum level specified.

2. It is essential that service personal 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, may produce

radiation that exceeds specifications.

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 a picture tube other than that specified or

make unrecommended circuit modifications to the

high voltage circuitry.

6. When trouble shooting and taking test 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.