Service manual

IM1015
SECTION IV
ADJUSTMENT
AND
MAINTENANCE
4.1
GENERAL
This
section
is
for
the
adjustment
procedures
and
maintenance
procedures
for
the
TD
series
monitor.
CAUTION
NO
WORK
SHOULD
BE
ATTEMPTED
ON
ANY
EXPOSED
MONITOR
CHASSIS
BY
ANYONE
NOT
FAMILIAR
WITH
SERVICE
PROCEDURES
AND
PRECAUTIONS
4.2
HV
SHUTDOWN
RESISTOR
REPLACEMENT
(R212)
Refer
to
figure
4-1
for
component
location
on
PWA
and
test
equipment
termination.
1.
Connect a
DC
voltmeter
+
lead
to
R216
and
the
-
lead
to
chassis
ground.
This
meter
is
for
monitoring
the
B+
voltage.
2. Connect one end
of
a
clip
lead
to
R211
and
the
other
end
to
chassis
ground.
This
will
disable
the
voltage
regulator
circuit.
3. Connect a
lOOK
range
resistor
decade box
across
the
male molex
pins
for
R212
and
set
the
decade box
for
300n
resistance.
4. Plug
the
monitor
AC
plug
(P1)
in
to
a 0-140 V
variac
and
set
the
variac
voltage
control
for
0
volts.
5.
You
are
going
to
determine
what
value
of
R212
that
causes
HV
shutdown
(loss
of
raster)
when
the
B+
voltage
is
59V
±lV.
a.
Turn on
the
monitor
and
place
the
brightness
and
contrast
controls
in
the
center
of
their
rotation.
b.
Turn on
the
variac
and
slowly
increase
the
AC
input
voltage
to
the
monitor
while
watching
the
B+
voltage.
Note
the
B+
voltage
reading
prior
to
HV
shutdown
(loss
of
raster).
6.
If
HV
shutdown
occurs
prior
to
59V
±lV,
increase
the
value
of
R212
and
repeat
step
5b.
7.
When
the
HV
shutdown occur-s
at
59V
±1
V,
note
the
decade box
resistance
value
and
use
this
resistance
for
R212.
8.
Install
R212
and
repeat
step
5b
to
varify
that
the
,shutdown
voltage
will
occur
at
59V
±lV.
4-1