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29FL94
29FL94
IMPORTANT SERVICE SAFETY PRECAUTION
IMPORTANT SERVICE SAFETY PRECAUTION
Ë
Ë
Service work should be performed only by qualified service technicians who are
Service work should be performed only by qualified service technicians who are
thoroughly familiar with all safety checks and the servicing guidelines which follow:
thoroughly familiar with all safety checks and the servicing guidelines which follow:
WARNING
WARNING
1.
1.
For continue
For
continued safety
d
should be attempted.
should be attempted.
2.
2.
Disconnect
Discon
nect
AC powe
AC
3.
3.
Semiconduc
Semic
onductor heat si
tor heat
when the chassis is operating.
when the chassis is operating.
4.
4.
The chas
The
chassis in this rec
sis in this
which are separated by
which are separated by
isolated (hot) ground system is for the B+ voltage
isolated (hot) ground system is for the B+ voltage
regulator circuit. The isolated ground system is
regulator circuit. The isolated ground system is
the low B+
the low B+
DC voltages and
DC voltages and t
the high voltage transformer.
the high voltage transformer.
To prevent electrical shock use an isolation
To prevent electrical shock use an isolation
transformer between the line cord and power
transformer between the line cord and power
receptacle, when servicing this chassis.
receptacle, when servicing this chassis.
SERVICING OF HIGH VOLTAGE SYSTEM
SERVICING OF HIGH VOLTAGE SYSTEM
AND PICTURE TUBE
AND PICTURE TUBE
When servicing the high voltage system,
When servicing the high voltage system,
remove the static charge by connecting a
remove the static charge by connecting a
10k ohm resistor in series with an insulated
10k ohm resistor in series with an insulated
wire (such as a
wire (such as a
ture tube ground and the anode lead. (AC
ture tube ground and the anode lead. (AC
line cord should be disconnected from AC
line cord should be disconnected from AC
outlet.)
outlet.)
1.
1.
Picture
Picture t
tube in this re
ube in this
implosion protection.
implosion protection.
2.
2.
Replace with tu
Repla
ce with
continued safety.
continued safety.
3.
3.
Do not
Do not
lift
lift p
pictur
icture tub
4
4
.
.
Handl
Handle t he pict u
e t he pict
shatterproof goggles and after discharging the high
shatterproof goggles and after discharging the high
voltage anode
voltage anode
safety, no
, no
modification
modification
of any
of any
power bef
r
before se
ore
servicin
rvicing.
g.
sinks are pote
nks are
potential sho
ntial
shock hazar
receiver ha
eiver
has two groun
s two
ground system
insulating material. The non-
insulating material. The non-
the secondary c
he secondary
test probe) between the pic-
test probe) between the pic-
receiver em
ceiver
employs inte
ploys
tube of the sa
be of the
same type nu
me type
number fo
e
tube by t
e by
the nec
he
neck.
k.
ur e t ube onl
r e t ube
only when wear
y when
completely
completely.
.
X-RADIATION AND HIGH VOLTAGE LIMITS
X-RADIATION AND HIGH VOLTAGE LIMITS
circuit
circuit
1.
1.
Be sure all
Be sure all s
procedures and instructions covering X-radiation. The
procedures and instructions covering X-radiation. The
only potential source of X-ray in current solid state
only potential source of X-ray in current solid state
ck
hazards
ds
TV receivers is the picture tube. However, the picture
TV receivers is the picture tube. However, the picture
tube does not emit measurable X-Ray radiation, if
tube does not emit measurable X-Ray radiation, if
d
systems
s
the high voltage is as specified in the "High Voltage
the high voltage is as specified in the "High Voltage
Check" instructions.
Check" instructions.
It is only when high voltage is excessive that X-
It is only when high voltage is excessive that X-
for
for
radiation is capable of penetrating the shell of the
radiation is capable of penetrating the shell of the
circuit of
ircuit of
picture tube including the lead in the glass material.
picture tube including the lead in the glass material.
The important precaution is to keep the high voltage
The important precaution is to keep the high voltage
below the maximum level specified.
below the maximum level specified.
2.
2.
It is essen
It is
essential tha
times an accurate high
times an accurate high
The calibration of this meter should be checked
The calibration of this meter should be checked
periodically.
periodically.
3.
3.
High volt
High
voltage shou
no higher. Operation at higher voltages may cause
no higher. Operation at higher voltages may cause
−
−
a failure of the picture tube or high voltage circuitry
a failure of the picture tube or high voltage circuitry
and;also, under certain conditions, may produce
and;also, under certain conditions, may produce
radiation in exceeding of desirable levels.
radiation in exceeding of desirable levels.
4.
4.
When the
When the
there is no possibility of
there is no possibility of
time a color chassis is serviced, the brightness should
time a color chassis is serviced, the brightness should
be tested while monitoring the high voltage with a
be tested while monitoring the high voltage with a
meter to be certain that the high voltage does not
meter to be certain that the high voltage does not
exceed the specified value and that it is regulating
exceed the specified value and that it is regulating
correctly.
correctly.
integral
gral
5.
5.
Do not us
Do not
make unrecommended circuit modifications to the
make unrecommended circuit modifications to the
mber
for
r
high voltage
high voltage
6.
6.
When
When tro
on a receiver with excessive high voltage, avoid being
on a receiver with excessive high voltage, avoid being
wearing
ing
unnecessarily close to
unnecessarily close to
Do not operate the receiver longer than is necessary
Do not operate the receiver longer than is necessary
to locate the cause of
to locate the cause of
2
2
service p
ervice
personn
ersonnel are awa
el are
tial
that servic
t
servicemen hav
emen
have availab
voltage meter.
voltage meter.
age
should always b
ld always
be kept at
e kept at
high volt
high
voltage regu
age
regulator is
lator is
an X-radiation problem. Every
an X-radiation problem. Every
use a pictu
e a
picture tube
re tube
other th
other
than that
circuitry.
circuitry
.
trouble shoo
uble
shooting and t
ting and
taking tes
aking
the receiver.
the receiver.
excessive voltage.
excessive voltage.
aware of the
re of the
e
available at all
le at all
the
the rat
rated value
ed value
operating prope
operati
ng
properly
rly
an that
specified o
specified
or
r
test measu
t
measuremen
rements
ts
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