Hitachi HTA-3F - Page 12

HITACHI
HTA-3F
TROUBLE
SH
OOTING
Key
input
not
resistered
Check
whether
or
not
the
unit
operates
normally
when
the
power
switch
is
turned
OFF
once
and
turned
ON
again
after
more
than
5
sec.
YES
Misoperation of IC503 controller
NO
Farol: NO
beac
ee
not
the
power
voltage
of
micro-computer
PAU
EF
power
\olibgo
econ
YES
YES NO
Check
whether
or
not
CE
terminal
@
of
1C503
is
set
to
? [asoefauity
High.
Is
Q508
normal?
Q508
faulty
NO YES
NO The circuit connected to Q508 base is faulty.
Faulty connection of the 9 or 10 core jumper lead wires
which connect the DISPLAY and TA P.W.B. or 0501-506,
0507-510 faulty.
Check
whether
or
not
when
depressed,
the
RETURN
signal
corresponding
to
the
depressed
key
is
WRITTEN
to
the
K
input
terminals
@)
—
(1)
of
1C503
.
YES
Frequency
indicated
on
the
display
cannot
be
received.
Is
the
power
supply
to
the
synthesizer
section
normal?
;
;
YES
Which
is
received,
FM
or
AM?
FM tuner
#
1C501 faulty
It
is
possible
to
receive
the
broadcast
when
the
wiring
to
the
VCO
terminal
TP.8
of
the
TA
P.W.B.
is
cut;
connect
Check voltages of Q802, 803, etc.
NO
AM
Is
the
FM
local
input
terminal
1s
the
AM
local
input
terminal
GO)
NO
Q151
faul
of
IC501
set
to
more
than
53m
of
IC503
set
to‘more
than
354mV?
aulty
YES
Is
the
FM
local
terminal
@
of
1C503
set
to
more
than
283mV?
; : NO
a
OC
stabilized
power
supply
ne
replace
varying
the
DC
voltage. Does it receive station:
YES NO
Are
0501,
502
normal?
Q501,
502
faulty
YES
= 13 =
Does not stop when a broadcast is received dur-
ing Auto-tuning operation :
Does the signal indicator light? =. .
YES
is the “zero” point adjustment checking of T202 dis-
criminator normal?
YES
Is S.D. input terminal @ of 1C503 is set to High level dur-
ing reception of a broadcast?
YES
1C503 faulty
Trouble with display tube
Does the display operate normally when the power switch
cut off once, and then turned on again after more than 5
sec?
is the power supply to the synthesizer section normal?
YES
z
:
Is the tap voltage of the filament winding (AC 3.8V) of the
power transformer — 17V?
YES
Is the filament voltage of the display tube approx. AC 3.8V?
YES
Is the input of the display tube checked properly?
NO
Are digit output terminals D1 — D6 and segment outpout
terminals Sa — Sg to the display P.W. B. from the TA
P.W.B. checked properly?
YES
Connection of 9 and 10-core jumper wire which connects
the TA P.W.B. and display P.W.B. faulty.
Auto-tuning operation is not performed and the
preset key is not accepted during FM auto-tuning
Is the power supply to the synthesizer section normal?
YES
Is FM local input terminal @ of |C501 more than 53mV?
YES
Is FM local input terminals @ of IC503 more than 283mV?
YES
Are 0501, 502 normal?
YES
1C503 faulty
CAUSE
NO
NO
NO
YES
NO
CAUSE
NO
NO
NO
NO
(Because S.D. signal from TA P.W.B.is more than 0.5V)
Signal strength weak
Drift of the zero point of T202
NO
1s Q509 normal?
Q509 faulty
YES
1C202 faulty
Misoperation of 1C503 controller
Check voltages of Q802, 803, etc.
D812 faulty
Power transformer faulty or wiring from the filament
winding of the power. transformer to the display P.W.B.
faulty.
Display tube faulty
Are digit output terminals 01 — 06
and segment output terminals Sa
— Sg of 1C503 normal?
NO 1C503 faulty
YES
1C502 faulty
(PLL is not locked)
Check voltages of Q802, 803, etc.
FM tuner pack faulty
1C501 faulty
0501, 502 faulty
—14-