Adjustment - Sharp MD-M3 Service Manual

TUNER SECTION
fL: Low-range frequency
fH: High-range frequency
• AM adjustment and confirmation
AM signal oscillator Frequency 400 Hz, 30%, AM modulation
Adjusting item Adjusting object
IF Adjust the indication of Set IF waveform
T351 set to 1,720 kHz. 450 kHz to maximum.
Frequency cover fL: T306 (530 kHz)
(VT line voltage of Adjust the indication
pin 20 of IC302) of set to 530 kHz.
fH: (1,720 kHz)
Tracking fL: T302 (990 kHz)
AM Loop Antenna
IF : Speaker Terminal
Freqency cover: IC302,Pin 20
FM signal oscillator
Loop Antenna
Figure 17-1 AM IF
• Erasing the registered broadcast station
When the power is off, press and hold the TUNER button and
the STOP button, and then press the POWER button.
All the registered stations are erased.
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
amplifieroutput and the VREF reference voltage is
compensated inside the IC.)
* Focus offset adjustment
* Tracking offset adjustment
(2) Tracking balance adjustment (waveform drawing 17-4
EFBL)
(3) Gain adjustment (The gain is compensated inside the IC
sothat the loop gain at the gain crossover frequency will
be 0dB.)
* Focus gain adjustment
* Tracking gain adjustment
ADJUSTMENT
Adjusting
method
fL: 1.1 ± 0.1 V
fH: 8.0 ± 1.3 V of
(Only confirmation)
Set the output of
speaker terminal
to maximum.
Electronic
voltmeter
UNIT
GND
• FM mute level adjustment
FM signal oscillator Frequency 1 kHz, 40 kHz
Frequency Adjusting
method
98 MHz 25 dB
FM signal oscillator
Figure 17-2 FM Mute Level
AM IF
T351
VR351
IC303
FM Mute Lebel
Figure 17-3 ADJUSTMENT POINT
T
Stopped
CH1=500mV CH2=200mV
DC 10:1
T
FDO
1
TE
3
EFBL
2
=Filter= =Offset=
Smoothing : ON CH1 :
BW : FULL CH2 :
CH3 :
CH4 :
– 17 –
MD-M3/M1
Adjusting
Adjusting object
object
VR351 Input: SO301
Output: Speaker
Electronic
Speaker
voltmeter
SO301
Terminal
UNIT
POWER/TUNER PWB
SO301
IC302
Antenna Terminal
20
FE301
T302
T306
AM Band Coverge
1999/04/05 20:26:47
CH3=1V 500ms/div
DC 10:1 DC 10:1 (500ms/div)
NORM:20kS/s
CH2
v/DIV
200mV
=Record Length= =Trigger=
0.000V Main : 100K Mode : SINGLE
0.000V Zoom : 2k Type : EDGE CH1
0.00V Delay : 0.0ns
0.00V Hold off : 0.2us
Figure 17-4
Terminal
AM Tracking