Service manual
Table Of Contents
No
raster,
no
sound
(81
is
abnormal)
NOTE
1702
locations in (
).
The regulator
PCB
assembly used in
1702
models differs
from
the
1701
power
PCB
assembly. The
B1
voltage circuits should be checked beginning
with
IC901.
[Cause]
Abnormal
B1
voltage indicates trouble in
the
power
supply circuit. When
B1
voltage is
not
only
low
but
also abnormally high, X701 (Q501)
of
the
X-ray protector is turned on, setting the collector voltage
to
0 V. The horizontal oscillator is then disabled resulting in no raster and no sound.
1 . When D
105,
R
105,
R
108,
R
109
are open, the base voltage
of
X 101 and X
102
rise
to
increase
B1
voltage
to
more
than
130V.
This causes
the
X-ray
protector
to
work,
resulting in no raster.
2.
If
the
base voltage drops as
when
R103
is open or
C105
is shorted,
the
B1
voltage is reduced
to
less than
40
V. This will
mostly
result in no raster, no sound.
3. When
the
B1
voltage drops
to
about
70
V, because
R91
0 is open and
D1
05
is shorted, the screen
becomes dark and
the
raster size is reduced because
of
insufficient
horizontal and vertical
amplitude.
C
START
)
!
Does
4.0A
fuse
blow?
,NO
~
YES
Can
B1
be adjusted
to
110
V
with
Rectifier including
power
supply I
B1
ADJ
R109?
transformer has failed.
YES
r----------------------1NO
Misadjustment Horizontal deflection
l Does the base voltage
at
X101
change I
circuit
has failed
when
picture is
with
B1
ADJ
R109?
small
with
B1
=
110
V.
t
NO
t YES
Is
the
emitter
voltage
of
X102
Does the
emitter
voltage
of
X10'1
correct? change
with
B1
ADJ
R109?
+
ABNORMAL
t NORMAL =
6.6V
NO
~
t
YES
D105
open
or
short
I
X102
open or short,
R105, R108,
X101,
R103
I
X02
has
I
R109
open.
C105
short
open
failed
18