Tuner Section - Sharp CD-BA250 Service Manual

CD-BA250/CD-BA2600

TUNER SECTION

fL: Low-range frequency
fH: High-range frequency
AM IF/RF
Signal generator: 400 Hz, 30%, AM modulated
Test Stage Frequency
AM IF 450 kHz
AM Band —
Coverage
AM Tracking 990 kHz
*1. Input: Antenna
*2. Input: Antenna
CD SECTION
• Adjustment
Since this CD system incorporates the following automatic
adjustment functions, readjustment is not needed when
replacing the pickup. Therefore, different PWBs and pickups
can be combined freely.
Each time a disc is changed, these adjustments are
performed automatically. Therefore, playback of each disc
can be performed under optimum conditions.
Items adjusted automatically
(1) Offset adjustment (The offset voltage between the head
amplifier output and the VREF reference voltage is
compensated inside the IC.)
* Focus offset adjustment
* Tracking offset adjustment
(2) Tracking balance adjustment (waveform drawing
Fig.14-2 EFBL)
(3) Gain adjustment (The gain is compensated inside the IC
so that the loop gain at the gain crossover frequency will
be 0 dB.)
* Focus gain adjustment
* Tracking gain adjustment
Frequency Setting/
Instrument
Display Adjusting
Connection
Parts
1,720 kHz T351 *1
530 kHz (fL): T306 *2
1.1 0.1 V
990 kHz (fL): T303 *1
Output: TP302
Output: TP301
R316
TP301
FM BAND
COVERAGE fL
Figure 14-1 ADJUSTMENT POINTS
FM RF
Signal generator: 1 kHz, 75 kHz dev., FM modulated
Test Stage
FM Band
Coverage
FM RF
*1. Input: Antenna
*2. Input: Antenna
CNP301
FM/AM LOOP
ANTENNA
MAIN PWB
T303
IC301
L312
T302
FM IF
FM RF
T351
T301
AM IF
TP302
CD ERROR CODE DESCRIPTION
Error
0001
0002
0101
0103
0201
0203
0302
0306
0307
0308
– 14 –
Frequency Frequency
Display
— 87.50 MHz T301(fL):
1.3 V
98.00 MHz 98.00 MHz L312
(10-30 dB)
Output: TP301
Output: Speaker terminal
AM
TRACKING fL
AM BAND
COVERAGE fL
T306
R357
State Code
[Servo System Error]
Cannot detect Pickup-in SW
DSP access error
[Error during close operation]
Open/Close SW not functioning (Low
Open/Close SW not functioning (High
[Error during open operation]
Open/Close SW not functioning (Low
Open/Close SW not functioning (High
[Error during skip operation]
Pickup-in SW is not detected
During Disc 1 search, Open/Close SW or Clamp SW
or Disc SW do not change to low.
Clamp SW not function (Low
Clamp SW not function (High
T
Stopped
CH1=500mV CH2=200mV CH3=1V
DC 10:1 DC 10:1 DC 10:1
T
FDO
1
TE
3
EFBL
2
=Filter= =Offset= =Record Length=
Smoothing : ON CH1 : 0.000V Main : 100K
BW : FULL CH2 : 0.000V Zoom : 2k
CH3 : 0.00V
CH4 : 0.00V
Figure 14-2
Setting/ Instrument
Adjusting Connection
Point
*1
50 mV
*2
High)
Low)
High)
Low)
High)
Low)
1999/04/05 20:26:47
500ms/div
(500ms/div)
NORM:20kS/s
CH2
v/DIV
200mV
=Trigger=
Mode : SINGLE
Type : EDGE CH1
Delay : 0.0ns
Hold off : 0.2 s