IMPORTANT SERVICE SAFETY PRECAUTION
Service work should
be
performed only by qualified service technicians who are thoroughly familiar with all
of the following safety checks and servicing guidelines.
WARNING
1.
For continued safety, do not attempt to modify
the circuit.
2.
Disconnect the AC power before servicing.
3. Semiconductor heat sinks are potential shock
hazards when the chassis is operating.
SERVICING THE HIGH VOLTAGE SYSTEM
AND
PICTURE TUBE
When servicing the· high voltage system, remove the
static charge by connecting a 20kohm resistor in
series with an insulated wire(such as a test probe)
between the chassis and the anode lead. (The AC
line cord should
be
disconnected from the
AC
out-
let.)
1. The picture tube in this display monitor employs
integral implosion protection.
2.
Replace with a tube
of
the same type and num-
ber for continued safety.
3.
Do
not lift the picture tube by the neck.
4.
Handle the picture tube only when wearing shat-
ter proof 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 a current
solid state display monitor
is
the tube. How-
ever,the picture tube does not emit measurable
X-ray radiation
if
the high voltage
is
as specified
in the "high voltage check" instruction.
3
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 serviceman have available at
all times an accurate high voltage meter. The
calibration
of
this meter should
be
checked pe-
riodically.
3. High voltage should always
be
kept at the rated
value -no higher. Operation at high voltages may
cause a failure
of
the picture tube or high voltage
circuitry and,also under certain conditions,may
produce radiation in excess
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 bright-
ness should4
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 troubleshooting and taking test measure-
ments on a display monitor with excessively high
voltage, avoid being unnecessarily close to the
display monitor.
Do
not
operate
the display
monitor longer than
is
necessary
to
locate the
cause of excessive voltage.
BEFORE RETURNING THE DISPLAY MONITOR
Fire
and
Shock Hazard
Before returning the display monitor to the user,per-
form the following safety checks:
