JVC HR-D540EE - Audio Circuit; Tuner;If Circuit

2.6 AUDIO CIRCUIT
Note:
Unless
otherwise
specified,
all
test
points
and
adjustments
are
located
on
the
MAIN
board.
Audio
Bias
TP31
(+)
R11
e
SOURCE
SEL
1)
Connect
a
millivoltmeter
between
TP31
and
TP32.
Level
TP32
(—)
(Bias
adj)
:
AUX
2)
Set
for
REC
mode
without
incoming
signal.
e SP mode 3) Adjust R11 for 1.9 mVrms.
@ REC mode
e No signal
2.7. TUNER/IF CIRCUIT
Note:
Unless
otherwise
specified,
all
test
points
and
adjustments
are
located
on
the
IF
board.
Equipment required:
1.
Oscilloscope
Gade
Shorter
than
8
cm
2. IF sweep signa! genrator with
suitable markers (PIF, etc.)
3. Sweeper probe (sweep signal supply
cable) as shown below.
ee
R: 750 Shorter than 5 cm
Sweeper probe
Fig. 2-7-1
T2 (VCO) e Sweep genrator 1) Use a sweeper probe as shown in Fiy, 2-7-1 and
out: 70 dBu connect the sweep generator outputto pin 1 of
(38.9 MHz) SAW 1.
e Tuner mode with- Adjust the sweep gain so that the waveform
38.9 MHz out antenna IN does not distort as observed with the oscillo-
Marker scope.
Connect the oscilloscope to pin 26 of IC1
(VIDEO
DET
OUT)
and
adjust
T2
to
align
the
waveform
with
the
frequency
markir
as
shown
Fig.2-7-20
|
in
Fig.
2-7-2.
cos
Alternatemethod:
—SSsss=CST
e
TV
broadcast
1)
Receive
a
color
broadcast
on
a
VHF}#!
channel.
e
Tuner
mode
2)
Adjust
T2
to
obtain
a
fine
pictrre
on
the
monitor.
VCO and sweep signal (beat)