Sharp MD-M3 Service Manual download pdf (Page 17)

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MD-M3/M1

SO301

Electronic

voltmeter

Speaker

Terminal

UNIT

FM signal oscillator

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

Figure 17-4

CD SECTION

EFBL

FDO

Stopped

CH1=500mV

DC 10:1

CH2=200mV

DC 10:1

CH3=1V

DC 10:1

500ms/div

(500ms/div)

NORM:20kS/s

=Record Length=

Smoothing : ON CH1 : 0.000V

CH2 : 0.000V

Main : 100K

Zoom : 2k

Mode : SINGLE

Type : EDGE CH1

Delay : 0.0ns

Hold off : 0.2us

CH3 : 0.00V

CH4 : 0.00V

BW : FULL

=Trigger==Filter= =Offset=

CH2

v/DIV

200mV

1999/04/05 20:26:47

GND

AM Loop Antenna

Loop Antenna

Electronic

voltmeter

IF : Speaker Terminal

Freqency cover: IC302,Pin 20

UNIT

FM signal oscillator

ADJUSTMENT

fL: Low-range frequency

fH: High-range frequency

• AM adjustment and confirmation

Figure 17-1 AM IF

TUNER SECTION

Adjusting item

Adjusting object

Adjusting

method

IF Adjust the indication of Set IF waveform

T351 set to 1,720 kHz.

450 kHz to maximum.

Frequency cover fL: T306 (530 kHz) fL: 1.1 ± 0.1 V

(VT line voltage of Adjust the indication fH: 8.0 ± 1.3 V of

pin 20 of IC302) of set to 530 kHz. (Only confirmation)

fH: (1,720 kHz)

Tracking fL: T302 (990 kHz) Set the output of

speaker terminal

to maximum.

AM signal oscillator Frequency 400 Hz, 30%, AM modulation

• FM mute level adjustment

Frequency

Adjusting

object

Adjusting

method

98 MHz 25 dB VR351 Input: SO301

Output: Speaker

Terminal

FM signal oscillator Frequency 1 kHz, 40 kHz

Adjusting object

Figure 17-2 FM Mute Level

• 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.

T306

VR351

T351

IC302

POWER/TUNER PWB

IC303

T302

FE301

AM IF

AM Tracking

AM Band Coverge

FM Mute Lebel

SO301

Antenna Terminal

Figure 17-3 ADJUSTMENT POINT

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 91 92

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Sharp MD-M3 Service Manual Page 17

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