Measurement And Adjustment; Tuner Section - Yamaha CT-7000 Service Manual

CT-7000

MEASUREMENT AND ADJUSTMENT

1. TUNER SECTION

Before Adjustment . . ... After 30 minutes aging with power switch on and each circuit board cover removed.
ADJUSTMENT
STEP
ITEM
1
Discriminator
Balance
(Normal)
2 IF Core Preset
3 Monaural Dis-
tor t ion Ratio
4 vco
Adjustment
5
Stereo Distor-
tion Ratio I
(Normal)
6
Stereo Distor-
t i on Ratio
II (Wide)
7
Stereo Distor-
tion Ratio
Ill
(Wide)
8
Wide Balance
9
Separation
I
(Normal)
10
Output
Level
11
Separation
II
(Normal)
12
Separation
Ill
(Wide)
18
TERMINAL TO BE
&
CONNECTED
INSTRUMENT REQUIRED
Received signal frequency near
center, antenna unconnected.
Antenna Terminal (300!2)
FM signal generator
98MHz/60dB.u
Antenna terminal (300!2)
FM signal generator
98MHz/60dB.u
Modulation:
400Hz/100% mono
Fixed output jacks (L, R)
Oscilloscope, Electronic volt-
meter, Distortion ratio meter
Antenna terminal (300!2)
FM signal generator
98MHz/60dB.u Unmodulated
MPX circuit board 19kHz T.P
Frequency Counter
Antenna terminal (300!2)
FM signal generator
98MHz/60dB.u. 100dB.u
Modulation 400Hz/1 00%
stereo
Fixed output jack (L, R)
Oscilloscope, Electronic volt-
meter, Distortion ratio meter
Same as Step 5
Same as Step 6
Same as Step 1
6.
Same as Step
6.
Same as Step
Check whether Step
6.
Same as Step
ADJUSTMENT HOW TO ADJUST
T301: Move the core from left
discriminator coil to right until the center
meter indicates
Secondary side
(upper) core then fix
RF Pack Move the core to the
IF core right and left to find
the location which af-
fords maximum signal
meter needle deflection.
T301: Move the core to the
discriminator coil left and right and set at
Primary side the location affording
(lower) core minimum distortion.
IF MODE switch: Test at both Normal and
Wide modes.
MPX circuit Set to 19kHz.
board VCO
adjustment
IF circuit Set for minimum dis-
board
tort ion.
VR201, 202
TC201, 202
RF pack Adjust for
IF core, RF2-5 distortion within limits
core that signal meter indi-
If standards not cation does
met, repeat (with
60dB1-1
Step 5. input).
IF circuit Set for minimum dis-
board tort ion.
VR203, 204
TC203
"0"
IF circuit Set for
board meter reading.
T201 coil
MPX circuit L &
Set R for maxi-
board
mum separation. (both
Separation L &
R)
Adj. Normal
L,R
MPX circuit
Set for limits shown at
board
right.
Level Adj.
L,R
1
0 has caused a change in the Step
Control circuit Set for maximum sepa-
board
ration.
Separation Adj.
Wide
RATING OR
STANDARD
''0'',
it in place.
INSIDE THIS MARk
-62dB
(0.08%)
19.000kHz±
20Hz (5Hz)
60dB/l, 62dB (0.08%)
-
IF MODE
=
100 dB/l, -57dB (0.14%)
60dBp
mm1mum
-62dB,
(0.08%)
100dBp
not drop
-57 dB,
antenna
(0.14%)
6 dB
- 2
(0.08%)
center
Same as
Step 1.
55dB
-1dBm ±
0.3dB
9
values; if so, repeat Step
55dB
REMARKS
When the power
switch is turned off
the meter
be sure
mechanical
reading
"0".
indicates See
Note 3.
Set at the same loca-
causes
tion which
the center meter to
"0".
indicate
If Normal and Wide
different, adjust bal-
ance.
NORMAL
60dB.u
: adjustment
required
100dB.u
:check only
acceptable
Carry out this step
if the Step 5 check
does not fall wi1:hin
the 100dB.u limi1:s.
Repeat the check in
7.
Step If the read-
ing is off consider-
7
ab ly, repeat Steps
&8.
9.
f o r bala nce
Adjust
if diff eren ce bet\l ll e en
&
R.
L