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— 5 —

Modulation is performed by the signal that is supplied from IC901 pin@¡ (pin#§).

If IC901 pin@¡ (pin#§) goes to “L”, the resistor R910 (R941) cannot be connected in parallel so that the current flowing through Q901 and
Q902 (Q911 and Q913) decreases and amplitude of the output signal also decreases.

• Either the large antenna or the small antenna is selected.  — The two antennas do not oscillate at the same time.

IC901 

→

 pin@£, pin@¶, pin@¡ 

→

 to the large antenna

IC901 

→

 pin@ª, pin#¡, pin#§ 

→

 to the small antenna

* The large antenna oscillates normally to read the data from the memory chip when a video cassette is brought closer to the video

cassette recorder.

• The antenna (small) oscillates in the following condition:

* When the TITLE key is pressed in the modes other than Cassette-In/REC END/REC, the system enters the EDIT menu.
* During Title Search/Blank Search
* Cassette IN 

→

 Pressing TITLE 

→

 Another tape is brought closer 

→

 Pressing TITLE.

pin

@¡

 (pin

#§

)

Fig. 2-4

When the modulation signal is present, the 
modulation signal goes to the "L" level.

pin

3

 

CN900 

Fig. 2-5

— 6 —

The antenna oscillation waveform is modulated (i.e., amplitude is changed).

Fig. 2-7

The IC in the tag reads the signal during 
this portion and obtains the data.

Fig. 2-6

Enlarged

Antenna

Antenna

AT-24 board

AT-23 board

Q914

@¡

@¶

IC901

CAR L-

WD L

CAR L+

CAR S-

WD S

CAR S+

(CXD8753G)

Q907

Q911

Q913

Q915

Q900

Q901

Q902

Q906

Q903

@£

@ª

#§

#¡

ML-15 board

— 7 —

•  Antenna (large) (AT-24 board)

• Antenna (small) (AT-23 board) (The reception method is the same as that of the antenna (large))

• The reception signal is rectified by D900.
• The reception signal is detected by Q904, R915 and C909.
• The reception signal is amplified by Q908.

• Switching between antenna (large) and antenna (small)

• Switching is performed by Q912 and Q910.

• The IC inside the tag changes the impedance of the circuit that is coupled by induction.

↓

• Amplitude of the signal that is induced by the antenna, changes.

↓

• Change of the signal amplitude is readout by the reception circuit of the ML circuit.

• The reception signal is rectified by D901.

• The reception signal is detected by Q905, R921 and C911.

• The reception signal is amplified by Q609.

Fig. 3-2

The positive (+) side of the 
reception carrier is detected.

Fig. 3-1

ML-15 board CN900 pin

3

 

(When the small antenna is used, 
ML-15 board CN901 pin

3

)   

— 8 —

@º

#¶ 

!ª

1

3

FIG. 3-3   

ML-15 board

Antenna

Antenna

A

T

-24 board

A

T

-23 board

D901

D900

Q905

+12V

RD

ANT

-L

 SW

ANT

-S SW

+12V

C91

1

0.001u

Q904

Q908

Q910

C909

0.001u

Q909

Q912

GND

GND

R918

4700

R915

4700

IC901

(CXD8753G)

IC900

(UPC393G2-E2)